Problem Dimensions / Evaluation of Past Studies ASAS in CARE CARE/ASAS Activity 1 CARE/ASAS/NLR/00-012 - Version 2.0 - December 23, 2000 CARE-ASAS Activity 1: Problem Dimensions / Evaluation of Past Studies European ASAS literature and study review By Ronald van Gent (NLR) Ariane Sinibardi (Eurocontrol) Anne Cloerec (Sofreavia) Claudio Vaccaro (Sicta) Allessandro Passarelli (Sicta) The Care ASAS Activity One consortium consisted of representatives of the following organisations: Eurocontrol Experimental Centre SICTA Sofreavia University of Delft DERA DFS INECO University of Glasgow NLR This investigation has been carried out under a contract awarded by EUROCONTROL, contract number C/1.161/HQ/EC/00. No part of this report may be reproduced and/or disclosed, in any form or by any means without the prior written permission of EUROCONTROL.
Transcript
Problem Dimensions / Evaluation of Past Studies ASAS in CARE
CARE/ASAS Activity 1
CARE/ASAS/NLR/00-012 - Version 2.0 - December 23, 2000
CARE-ASAS Activity 1:Problem Dimensions / Evaluation of Past Studies
European ASAS literature and study reviewBy
Ronald van Gent (NLR)
Ariane Sinibardi (Eurocontrol)
Anne Cloerec (Sofreavia)
Claudio Vaccaro (Sicta)
Allessandro Passarelli (Sicta)
The Care ASAS Activity One consortium consisted of representatives of the
following organisations:
Eurocontrol Experimental Centre
SICTA
Sofreavia
University of Delft
DERA
DFS
INECO
University of Glasgow
NLR
This investigation has been carried out under a contract awarded by EUROCONTROL, contractnumber C/1.161/HQ/EC/00.
No part of this report may be reproduced and/or disclosed, in any form or by any means without theprior written permission of EUROCONTROL.
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Summary
The main objective of the CARE-ASAS Activity One is to provide a framework to structure the issuesinvolved in European ASAS research, so as to make more efficient use of acquired expertise and
record pending results. These objectives are to be met through a literature review and synthesis. For
that purpose, a list of major ASAS-related European efforts to be reviewed was established, andprojects were distributed among partners of the consortium.
This document is the initial draft of Eurocontrol participation, which consists in reviewing
EMERALD, TORCH, 3FMS FREER, JANE, NEAN and NEAP, FARAWAY 1&2, TELSACS,SUPRA and MAICA projects. The consortium defined a set of questions relevant to ASAS to be used
as a guideline for each project review. The projects addressed in this document provided answers to
the following questions:
Technological issues:• Are CNS requirements provided, and if so in what way and what are the conclusions?• Are DST’s (Decision Support Tools) described (including CD& R and CDTI’s), and if so in what
way and what are the conclusions?
ATM Performance issues:• Are there any results related to :
• Capacity• Safety
• Efficiency
• Environmental issues, and if so in what way and what are the conclusions?
• Are Transitions aspects taken into account, and if so in what way and what are the conclusions?
• Are Flow Management aspects taken into account, and if so in what way and what are theconclusions?
Human Factors:Have Human-in-the-loop data been produced, and if so in what way and what are the conclusions?
Economical Aspects:Are business cases (cost/benefit analyses) being provided, and if so in what way and what are the
conclusions?
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Institutional Aspects:• Are responsibilities, rules and/or procedures described for aircraft, air traffic providers, the
combination/integration of both and /or AOC centres, and if so in what way and what are theconclusions?
• Are other issues being described such as:
• Standardisation• Certification
• Legal issues
, and if so in what way and what are the conclusions?
This report shows as a main conclusion that the ASAS is being studied very actively within Europe.
That fact is not only shown by the projects discussed within this report (a number of which are still on-going), but also by the number of projects recently started (chapter 3). These studies produce a large
amount of data, as is shown by this report. However the diversity between the studies are very large as
is shown by the previous chapter. Many different ASAS concepts are being studied, all with differentassumptions about the way ahead. If the issues involved are to be structured (as is the main aim of
CARE ASAS) it is recommended that CARE ASAS should derive a road-map concerning the
introduction of the ASAS. Activity 4 could be modified such that the present objective applicationselection, would include a road-map concerning the introduction of the ASAS. The Eurocontrol OCD
document (see annex..) could be regarded as a well accepted end-goal for this purpose.
The most striking diversity is seen regarding the applied CD& R algorithms. It is therefore
recommended to include an extra CARE ASAS activity to compare the different CD& R rules. This
activity should take the work performed by the RTCA SC 187 into account, since they are presentlyproducing material regarding CD& R algorithms for the ASAS.
The different ADS-B implementations are presently covered by an Eurocontrol ADS programme.Therefore no recommendation regarding ADS-B is made.
The third recommendation concerns a common set of metrics to be used for Human Factors issues.This report shows that human factors are studied in a very diverse way, which could be a factor in the
different outcome of the studies regarding CDTI implementations and ATM performance results.
CARE ASAS activity 2 has as an objective to develop a common set of metrics, definitions andscenarios and it is recommended to do the same regarding Human Factors measures. This would
probably mean an extra activity for CARE ASAS.
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Contents
List of Acronyms ...................................................................................................................................................................10
1.1 Identification of Scope ...........................................................................................................................................14
1.2 Organisation of Report.........................................................................................................................................16
2 Study Analysis.............................................................................................................. 19
2.1 Review of 3FMS project........................................................................................................................................19
Detailed review of 3FMS documents/project.................................................................................................................20
2.1.1.3 Human Factors ............................................................................................................................................23
2.2 Review of EMERALD project............................................................................................................................25
2.3 Review of TORCH project...................................................................................................................................34
2.4 Review of MAICA project....................................................................................................................................39
Detailed review of MAICA documents/project.............................................................................................................40
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2.5 Review of Glasgow University Papers...............................................................................................................45
2.6 Review of CENA ASAS work ..............................................................................................................................49
Detailed review of the CENA work................................................................................................................................. 50
2.6.1.3 Human factors............................................................................................................................................. 59
2.7 Review of the FREER project.............................................................................................................................62
Detailed review of the FREER project ........................................................................................................................... 63
2.9 Review of FARAWAY project............................................................................................................................81
Detailed review of the FARAWAY project ................................................................................................................... 83
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2.9.1.3 Human factors .............................................................................................................................................84
2.10 Review of the SUPRA project.............................................................................................................................87
Detailed review of the SUPRA project............................................................................................................................88
2.10.1.2 Human factors ........................................................................................................................................90
2.11 Review of the NLR/NASA Free Flight work...................................................................................................91
Detailed review of the NLR work....................................................................................................................................91
2.11.1.3 Human factors ........................................................................................................................................99
3.2 NEAN Update Program (NUP).........................................................................................................................104
Organisation and development model........................................................................................................................... 105
Tiger Teams ....................................................................................................................................................................... 105
THE AFAS PROJECT .................................................................................................................................................... 109
3.3.1.1 Description of project-results ................................................................................................................ 110
3.3.1.3 The project team....................................................................................................................................... 112
3.3.1.7 The project team....................................................................................................................................... 114
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Next Generation Satellite Systems Study.....................................................................................................................120
ASAS Feasibility and Transition Issues .......................................................................................................................122
4 Related projects .........................................................................................................125
5 CARE ASAS ACTIVITY 1 workshop......................................................................133
6 Summary of results and discussion.....................................................................134
6.1 Classification of ASAS projects:...................................................................................................................... 135
Decision support tools .....................................................................................................................................................137
6.4 Human factors issues.......................................................................................................................................... 141
GLASGOW University Papers ...................................................................................................................................... 146
CENA documents ............................................................................................................................................................ 146
SUPRA documents .......................................................................................................................................................... 150
Annex B. Detailed results of 3FMS project.............................................................151B.1 Detailed description of 3FMS CDTI .............................................................................................................. 151
B.2 Conclusions and Recommendations of the human-in-the-loop evaluation............................................. 156
Annex C. Detailed results of EMERALD project....................................................161C.1 List and Classification of Potential ASAS applications ............................................................................. 161
C.2 Requirements for Decision Support Tools .................................................................................................... 164
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Annex D. CENA..............................................................................................................177
Annex E. FREER............................................................................................................183
Annex F. NEAN-NEAP .................................................................................................191
Annex G. FARAWAY.....................................................................................................197
Annex H. PETAL ............................................................................................................201
Annex I. TELSACS ......................................................................................................207
Annex J. OCD EXECUTIVE SUMMARY...................................................................211
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1 Introduction
1.1 Identification of Scope
Airborne Separation Assurance System (ASAS) is seen as part of a broader future ATM concept that
strives for increased airspace capacity and traffic flexibility, while enhancing traffic awareness. It islikely that evolution toward a mature ASAS scenario would incrementally transfer more separation
responsibility from ATC to the flight-deck. The ASAS aims to exploit advances in flight-deck
technologies (e.g. ADS-B and air-to-air data-link) to improve the safety, capacity and efficiency of airtraffic.
The evolution to a mature ASAS environment is likely to be via phased implementation. Along theway, compatibility must be assured between current and future systems / procedures. Before the
ASAS can be realistically implemented, questions must be answered with respect to, for instance:
technical implementation, airspace redesign, financial costs and benefits, safety assessment, operator(both pilot and controller interfaces), and operational procedures.
So far, a great deal of Research and Development (R&D) effort has been carried out into AirborneSeparation Assurance System (ASAS). Unfortunately, this work has tended to be carried out in an
isolated, uncoordinated manner.
The main objective of the CARE-ASAS (Co-operative Actions of R&D in EUROCONTROL -
Airborne Separation Assurance System) Activity 1 is to provide a framework to structure the issues
involved in European ASAS research, so as to make more efficient use of acquired expertise and alsorecord pending results. These objectives are to be met through a literature review and synthesis, as
well as verification with the stakeholder community.
CARE stands for Co-operative Actions of R&D in EUROCONTROL. CARE has been set-up by the
EUROCONTROL Agency to define co-operative actions which address R&D issues of high priority
making use of the fact that co-operation has value in fostering motivation and exchange of ideas,bringing together different approaches, cultures competencies, forging common views and solutions.
CARE is meant to support the ATM2000+ Strategy calls for involvement of all relevant stakeholdersin all phases of the lifecycle, making efficient use of resources through collaborative projects with
extensive partnership, facilitating implementation of the results of R&D.
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CARE-ASAS Activity 1 intends to review a range of ASAS work, both past and current. This will
include only research carried out in Europe (e.g. European Commission DG7 and DG12 4th and 5th
Framework activities). US ASAS efforts will be covered by a separate American project funded byNASA and performed by Seagull. Co-ordination with Seagull will ensure coverage of US relevant
literature; major ASAS-related European efforts that the Activity 1 team intends to review include (but
project to develop add-on ASAS capabilities for existing civil FMSs;
• The EMERALD (Emerging Research and Technical Development Activities of Relevance to
ATM concept Definition) project, and its successor EMERTA (EMErging TechnologiesOpportunities, Issues and Impact on ATM), which focus on the selection of emerging
technologies in the context of the safety-dominated requirements of EATMS (European Air
Traffic Management System). This work addresses ASAS, as well as satellite-based CNS(Communication, Navigation and Surveillance). EMERALD made an initial assessment of
capabilities (both technical and operational) to support ASAS operations, and its report will
therefore be an important input to the proposed effort;
• TORCH (Technical, EcOnomical and OpeRational Assessment of an Air Traffic Management
Concept AcHievable from the year 2005) specified a 2005+ ATM (Air Traffic Management)operational concept to complement the ATM 2000+ strategy, and specified appropriate CNS/ATM
options;
• MAICA (Modelling and Analysis of the Impact of the Changes in ATM) -a European
Commission funded project to evaluate performance of ATM stakeholders in terms of capacity,
efficiency, and safety, and assessing how these would likely be influenced by advanced in airports,ATC (Air Traffic Control) and aircraft systems likely under a future ATM system;
• AFMS (Advanced Flight Management System) was a 4th Framework study into futurerequirements for civil Flight Management System (FMS), to support advanced ATM concepts;
• The CENA work which investigates ASAS operational procedures and general ASAS issues;
• FREER, (Free-Route Experimental Encounter Resolution) a EUROCONTROL project to
investigate state-of-the-art technologies for airborne conflict resolution, trajectory optimisation,and situation awareness advisories, which is being conducted in two phases: FREER 1 explored
airborne autonomy under low density traffic conditions, whilst FREER 2 addresses partial
airborne autonomy under high density traffic conditions;
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• The related JANE (Joint Air Navigation Experiments), NEAN (Northern Europe ADS-B
Network) and NEAP (North European CNS/ATM Application Project) efforts to demonstrateADS-B (Automatic Dependent Surveillance - Broadcast) capability by operating a large number
of ADS-B ground stations and aircraft in several countries throughout Europe;
• PETAL (Preliminary Eurocontrol Test of Air/ground data-link Project) — EUROCONTROL
data-link project in which advanced data-link functionality was demonstrated in upper airspace;
• FARAWAY (Fusion of Automatic Dependent Surveillance and RAdar data through two-WAY
data link) - The objective of this European Commission funded project was to investigate the
enhanced operational performance of ground surveillance and aircraft navigation through the useof ADS/TWDL (Automatic Dependent Surveillance/Two Way Data Link), using appropriate
fusion of ground generated surveillance data with aircraft localisation data to ground by air to
ground links;
• Additional ASAS-related work carried out at various of the consortium partners-such as NLR’s
efforts to develop ASAS displays, CD&R (Conflict Detection and Resolution) procedures andalgorithms, and real-time evaluations of pilot/ controller workload, safety, etc.
1.2 Organisation of Report
Chapter 2 of current the document contains the projects reviewed:• Section 2.1: review of the 3FMS project,
• Section 2.2: review of the EMERALD project,
• Section 2.3: review of the TORCH project,• Section 2.4: review of the MAICA project.
• Section 2.5: review of the Glasgow University papers
• Section 2.6: review of the CENA ASAS work,• Section 2.7: review of the FREER project,
• Section 2.8: review of the projects JANE, NEAN and NEAP
• Section 2.9: review of the FARAWAY project• Section 2.10 : review of the SUPRA project
• Section 2.11 : review of the NLR/FAA/NASA project on the ASAS subject.
Each project review is structured as follows:
• Project overview (scope, duration and current status of the reviewed project),
• Documentation overview (list of the main documents used for the review),
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• Detailed review of the project, based on guideline questions defined by the consortium and listed
bellow:
Ø Technological issues- Are CNS requirements provided, and if so in what way and what are the conclusions?
- Are Decision Support Tools described -including CDR (Conflict Detection and Resolution)
and CDTI (Cockpit Display of Traffic Information)-, and if so in what way and what are theconclusions?
Ø ATM Performance issues:
- Are there any results related to :§ Capacity
§ Safety
§ Efficiency§ Environmental issues
And if so in what way and what are the conclusions?
- Are transition aspects taken into account, and if so in what way and what are theconclusions?
- Are Flow Management aspects taken into account, and if so in what way and what are the
conclusions?Ø Human Factors:
- Have Human-in-the-loop data been produced, and if so in what way and what are the
conclusions?Ø Economical Aspects:
- Are business cases (cost/benefit analyses) being provided, and if so in what way and what
are the conclusions?Ø Institutional Aspects:
- Are responsibilities, rules and/or procedures described for aircraft, air traffic providers, the
combination/integration of both and /or AOC centres, and if so in what way and what arethe conclusions?
- Are other issues being described such as:
§ Standardisation§ Certification
§ Legal issues
, and if so in what way and what are the conclusions?
Chapter three discusses a number of European ASAS projects which are on-going and have not beenincluded in the main section of the report. However, it was felt that they should be mentioned and
taken into account.
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Chapter four discussed projects which were reviewed but were not directly related to the ASAS
subject. They are, however, included for the consortium felt that a number of result were useful for the
ASAS domain.
Chapter five briefly discusses a workshop held with stakeholders to discuss the findings of the
consortium and their draft report.
Chapter six summarises and discusses the findings.
Chapter seven finally presents the conclusions and recommendations.
Since the revised documents are named and listed in each paragraph discussing the project and inAnnex A, no separate reference list has been included.
To facilitate the use of the current document, only the main information was included in the body ofthe document. Additional information can be found in the annexes.
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2 Study Analysis
2.1 Review of 3FMS project
Project overview
3FMS (Free Flight, Flight Management System) project started in January 1998 and is due to finish in
December 2000.
The objective of 3FMS project is to prepare an early definition of a Flight Management System to
operate in a free flight ATM environment.
The main expected achievements of the project are:
• The identification of a free flight avionics architecture around the next generation of FMS,• The definition of the free flight functions for the new Airbus FMS,
• An evaluation and demonstration of free flight operation with a prototype FMS in an airbus flight
simulator in combination with a research ATC centre,• A list of recommendations for the implementation of the future free flight concepts in the
European ATM environment.
The following onboard functions will be addressed in the project:
• Aircraft separation using traffic information broadcast by surrounding traffic, detecting andresolving traffic conflicts,
• Anticipatory terrain avoidance,
• Weather avoidance based on on-board weather information,• Taxi management,
• Communication functions (air-ground and air-air),
• Human - machine interface functions.
The FMS prototype development is currently ongoing and the human-in-the-loop evaluation has not
yet been conducted.
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Documentation overview
The 3FMS reference documents are listed in Annex A. They relate to the technical approach of theproject, which follows a classical R&D life cycle: definition, design and prototyping, development,
integration, functional validation and operational evaluation.
Most of the 3FMS documents deal with the software design of prototype elements, which is too
technical for this review. Therefore, only a few of these documents will be reviewed in detail. The
selected documents bring different elements of interest, regarding CARE-ASAS activity One point ofview:
• WP 2.6 HMI-DD (Human Machine Interface Design Document) provides a description of theprototype HMI (Human Machine Interface) as well as results of a human-in-the-loop evaluation of
CDR and HMI.
• WP 5.1 ESDD (Evaluation Scenario Definition Document) raises some high level issues affecting
the Free Flight, and uses them as a basis for further human-in-the-loop 3FMS evaluation.
Detailed review of 3FMS documents/project
The following CARE ASAS subjects are covered by the 3FMS project:
• A description of the CDTI
Both NLR and Aerospatiale shall provide a CDTI for the 3FMS project.The HMI-DD document describes in details the CDTI provided by NLR and briefly presents
Aerospatiale’s CDTI.
• Human-in-the-loop evaluation
The 3FMS CDTI has been evaluated in a mock-up environment with the participation of seven
technical or test pilots.
2.1.1.1 Technological Issues
2.1.1.1.1 Description of 3FMS CDTI
The WP2.6 HMI-DD document describes the HMI design supporting the crew while operating in freeflight airspace using conflict detection (CD) and conflict resolution (CR).
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Different options are proposed within the NLR’s CDTI description, with the objective to compare
different Navigation Display formats in support of the pilots’ separation assurance task with use of
ASAS/CDR.
The emphasis is put on usefulness and layout of a Vertical Profile display due to the anticipated
importance of vertical resolution advisories due to flight economics. The ND variants are the so-called‘Map Only’, ‘Map plus Along Track Profile’ and ‘Map plus Along Route Profile’
• The Map Only variant, being the reference, is characterised by:no explicit vertical profile presentation
• The Map + Along Track Profile with distance axis variant has a Vertical Profile display integratedbelow the Map display. The Profile mode is characterised by:
Ø ‘along current aircraft track’ distance on the horizontal axis
Ø accurate indication of barometric altitude on the vertical axisØ proximate traffic presentation
Ø range and altitude scale can be set by the pilot
Ø Profile range is directly coupled to the Map range
• The Map + Along Route Profile with time axis variant is a second Vertical Profile presentation,
which is also integrated below the Map display. This Profile mode is characterised by:Ø ‘along route’ time on the horizontal axis (1-2-1 relation with along route distance)
Ø global indication of barometric altitude on the left vertical axis
Ø accurate indication of vertical speed on the right vertical axisØ traffic presentation only in case of a conflict situation
Ø altitude and vertical speed scales can be set by the pilot
More detail on these three formats of CDTI can be found in Annex B.
2.1.1.2 ATM Performance Issues
Some other CARE ASAS subjects shall be addressed during the future 3FMS evaluation, which is
meant to be a conceptual study of the feasibility of the chosen free flight concept and the chosentechnological implementation.
Currently, the only available data on future 3FMS evaluation lies in the WP5.1 ESDD document. Thisdocument states a number of free flight high level issues that interest 3FMS, and from which a number
of 3FMS experimentation issues will be derived.
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Regarding the review, this document simply brings some directions of research and evaluation on
various subjects that interest CARE-ASAS activity one. The following is a brief summary of these
subjects.
2.1.1.2.1 Capacity and Efficiency issues
The ESDD document defines the following directions of research for Capacity and Efficiency issues:
• Are the conflicts detected and solved in time regarding safety and pilot/controller acceptance?
• How sensitive is the 3FMS to traffic density in FFAS (Free Flight AirSpace) and is an increase ofairspace capacity expected based on this sensitivity compared to current airspace capacity based
pilot and controller feedback?
• Is this level of sensitivity sufficient for a 3FMS based free flight operation to be capable ofhandling an increase in airspace capacity compared to the current situation?
• Does the use of 3FMS in FFAS reduce fuel consumption due to flight optimisation calculations in
4D compared to current operations leading to benefits for airlines?• Does the use of 3FMS in FFAS reduce trip time due to efficient conflict solving compared to
current operations?
• Does the use of 3FMS in FFAS reduce delays due to accurately meeting the RTA (Required Timeof Arrival) compared to current operation?
• Can 3FMS support weather avoidance effectively and efficiently other than by using current
available weather information (weather radar for example)?
2.1.1.2.2 Transition aspects
ESDD document defines the following directions of research for the transition aspects:
• Is the new airspace structure, consisting of FFAS and MAS (Managed AirSpace) with its
transitions, acceptable for both pilots and controllers?
This question takes on different meanings, according to the perspective of either a pilot or a controller
and the phase of flight:• For departure:
Ø For the flight crew the operation in MAS during departure is equal to current day practice and
the question for the crew is basically: when can the crew accept the traffic separation tasksduring the climb phase with respect to other crew tasks during the climb?
Ø For the controller the question is: how much time does one need to create an outbound traffic
flow which is not conflicting with itself nor other traffic streams so one can hand over theseparation responsibility to the crew?
• For arrival:
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Ø For the flight crew, the question is: until what moment in flight can the crews perform the
separation task without getting into workload problems with other crew task during the descent
and arrival phase?Ø For the controllers the question is, how much time (i.e. airspace size) do they need in order to
create a well-sequenced, non-conflicting inbound traffic stream?
2.1.1.3 Human Factors
The evaluation focused on the following questions:• what type of Conflict Detection & Resolution (CD&R) is acceptable?
• what type of Human Machine Interface (HMI) is needed by the flight crew?
Another research item of this evaluation was the type of operation:
• the 3FMS focuses on “managed mode operation”, meaning that a conflict is solved by means of an
update of the FMS route which needs to be reviewed and activated by the pilot,• a second type of operation is the so called “selected mode” in which the pilot solves a conflict by
using a heading change or a vertical speed change based on a conflict resolution advisory and
thereafter returns to the original flight plan.
Here follow the main conclusions brought by the pilots’ answers. Conclusions include the pilots’
reactions against the evaluated system, observation of the pilots preferences and recommendations forfuture system designs.
• Free flight is promising in the eyes of pilots.
• Traffic should be presented with little detail.• Traffic at a long range should not be presented at all.
• The Vertical Situation Display shall not be used to monitor the traffic situation in general, but
shall be used in case of a conflict.• The FMS shall present one resolution only; second best solutions shall be available on pilot’s
request only.
• FMS resolution shall correspond with pilot’s mental picture.• The priority resolution process should be hidden.
• The Vertical Situation Display (VSD) should contain a Vertical Speed (V/S) scale for estimating
vertical manoeuvres.
More detail on conclusions of the CDTI evaluation will be found in Annex B.
Human-in-the-loop data
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One purpose of the ESDD document is to define what feedback is expected from the stakeholders. The
following high-level measures are foreseen:
• Do pilots accept the use of 3FMS in FFAS and MAS?• Does the crew workload increase while using the 3FMS in FFAS and MAS compared to current
operations under similar traffic conditions?
• Are crew procedures in FFAS and MAS acceptable and valid?• Is the controller able to monitor and acquire sufficient situation awareness for intervening or
providing support in case this is required during FFAS operation?
• Do controllers accept the 3FMS MAS operation support by means of station keeping?
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2.2 Review of EMERALD project
Project overview
The EMERALD (Emerging Research and Technical Development Activities of Relevance to ATM
Concept Definition) project started in February 1997 and ended in October 1998.
The EMERALD project was designed to provide recommendations for future Research and Technical
Development (RTD) activities for CNS development in support of future ATM concepts, covering theperiod 1997 to 2015. As such it was not very compatible with the set-up of this analysis. Nevertheless
the project is of very high importance to the ASAS domain.
The aims of the EMERALD project may be summarised as:
• To review potential Air Traffic Management (ATM) concepts, CNS technologies and fleetequipage at a high level in order to identify shortcomings in current RTD activities;
• To study in greater detail:Ø the application of ADS-B technologies to the emerging ASAS concept;
Ø the impact of the RNP (Required Navigation Performance) concept on the future of ATM;
• To disseminate the project results throughout Europe to enable organisations to develop and
exploit the technologies as early as possible, thereby providing the opportunity for Europe to
influence, and benefit from, the global civil aviation agenda concerning CNS technology.
The project was split into six work packages:
• The first four work packages (WP1 to WP4) of the project identified the emerging CNS research
and technical development (RTD) activities which have an impact on the definition of concepts
for a future European Air Traffic Management System (EATMS).
• Work packages five and six took a deeper look at two particular aspects of future CNS systems. In
particular, WP5 performed a study of ASAS applications and an assessment of the suitability ofADS-B techniques for the development of ASAS applications.
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Documentation overview
The EMERALD project produced eight deliverables. This review is mainly interested in the sixthdeliverable, which concerns the study of ASAS applications.
In addition to the “volume 6” deliverable, this review also studied some internal documents of WP5,
which provide details on issues relevant to CARE ASAS activity one.For further detail on EMERALD reference documents, refer to Annex A.
Detailed review of EMERALD documents/project
In WP5.1 report, 32 ASAS applications were identified (see the corresponding list and classification in
Annex A), and the three most promising of them -in terms of expected benefits, airspace capacity,flight efficiency, safety- were selected for further study:
To assess the feasibility of each application, the following points have been investigated in WP5.2:• The aim of the application,
• The benefits and constraints,
• The safety assessment,• The data and data-link requirements,
• The pilot interface and ATC interface requirements,
• The operational procedures.
Through its approach, the EMERALD project covers many subjects of CARE ASAS activity One
review:
• CNS requirements are provided
Requirements have been analysed for each of the three selected applications; then VDL mode4 andADS-B were assessed against these requirements.
• Decision Support Tools are describedVarious requirements for the pilots’ and the controllers’ interfaces have been identified for each
selected application.
• A safety assessment is carried out on the 3 selected applications
• Transition aspects are taken into account
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The transition from a mixed population of ADS-B and non-ADS-B equipped aircraft to a
population of fully equipped aircraft is studied on both operational and technical aspects.
• Operational procedures are described for the 3 selected applications
2.2.1.1 Technological Issues
2.2.1.1.1 CNS requirements
The WP5.2 report describes data links requirements with regard to integrity, continuity of service and
performance parameters.
The following table provides the summary of data-link requirements for each selected application:
Applications
Data-link requirement Longitudinal Station
Keeping
Closely Spaced Parallel
Approach
Autonomous Aircraft
State Vector Acquisition Range 40 NM 10 NM 120 NM
Mode Status Acquisition Range 40 NM 10 NM 120 NM
On condition Acquisition Range N/A N/A 120 NM
Availability Dual 10-6, single 10-3 Dual 10-6 Dual 10-6, single 10-3
Integrity <10-6 <10-6 10-6
Latency <1.5s <1.2s <1.5s
Nominal Update Period <=10s <=1.5s <=10s
Table 1 CNS requirements from the EMERALD project
VDL Mode 4 (STDMA: Self-organised Time Division Multiple Access) and 1090 MHz (Mode S
signals) have been considered to determine their suitability for ASAS applications including the
practicality of implementing onboard an aircraft within the current airborne architecture.
The main conclusions of the WP5.5 report are:
• ASAS applications can be supported by both technologies, which have different levels of maturityand different performances, but none of them is suitable for all applications. Furthermore, ADS-B
may not be sufficient to support all applications, and may require a cross-link capable device.
• During the transition period, to address the partial equipage of the fleet, inducing a partialvisibility of the surrounding traffic, the TIS (Traffic Information Service) or TIS-B (TIS
Broadcast) could be used.
• The common point of failure of ASAS applications is the aircraft navigation system. This impliesthat ASAS applications will require a position validation.
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• For all ASAS applications except TSA (Traffic Situation Awareness) applications, the integrity
and availability requirements demand a redundancy, especially in the communication channel. A
dual communication channel would be satisfying. Furthermore, such applications needinformation about the intent of other aircraft in order to work efficiently and safely.
• The ASAS/ACAS (Airborne Separation Assurance System / Airborne Collision Avoidance
System) compatibility should be carefully assessed in order to ensure proper acceptance by pilots.
2.2.1.1.2 Decision Support Tools
EMERALD project identifies various requirements for the pilots’ and the controllers’ interfaces, for
each selected application.
The following is a summary of the main recommendations for the pilot’s interface, which are furtherdetailed in Annex C.
Pilot’s interface
• Some general considerations common to the three applications were identified, which cover:
Ø Various recommendations for display format, like integration of the ASAS symbology conflict
detection and the TCAS (Traffic alert and Collision Avoidance System) one, prioritisation of
the detected conflicts as a function of their time horizon, etc.. Identification of data to bedisplayed: graphical display of separation advisories for the short-term / long-term conflict
resolution.
• Requirements for Longitudinal Station Keeping application identify that visual aids could be
useful to indicate:
- the preceding aircraft capture procedure (speed, acceleration/deceleration rate), based onaircraft performance,
- the preceding aircraft speed following procedure: maintain X nm +/- Y nm between two
aircraft (e.g. 7 nm +/- 0,5 nm).- the preceding aircraft speed change following procedure: need of co-ordination between the
two aircraft.
- the standby procedure after preceding aircraft has left the stream.
• Requirements for the Closely Spaced Parallel Approach application identify three different zones
which can be displayed:- the basic ASAS protection zone which is a circle around the aircraft.
- the Non Transgression Zone which is like a wall between the two runway axis.
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- the tunnels delimiting the allowed airspace for approach and landing around the two runway
axis.
• Requirements for Autonomous Aircraft application identifies data to be potentially displayed for
each selected aircraft:
- flight identifier- relative altitude
- relative bearing
- relative range- closure rate
- ground speed
- ground track indication- potential conflict status
- conflict resolution assistance data
2.2.1.2 ATM Performance Issues
2.2.1.2.1 Safety Assessment
WP5.2 Report carries a safety assessment of the 3 selected ASAS applications.
The hypotheses taken by the EMERALD project were the following:
• The objective is to ensure less than 10-9 collisions per flight hour between two Commercial
Aircraft.The underlying hypotheses are:
- the ASAS application will be supplied in 10 years and operated for 15 years,
- the traffic will be doubled in periods of 10 years,- the aim is to keep the air traffic safety at the same level of one collision per 10 years.
• For each assessed application, a raw collision risk is estimated (i.e. a collision risk when aircraft
with their flight crew fly on their route without any surveillance assistance neither from the airsystems nor from the ground systems):
- for Longitudinal Station Keeping application, 1 collision per 1000 flight hours,
- for Closely Spaced Parallel Approach application, 1 collision per 100 flight hours,- for Autonomous Aircraft application, 1 collision per 1000 flight hours,
• The failure rate of the complete ASAS function was established to be:
- Integrity: 10-5
- Availability: 10-3
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Based on the figures above, the approach involved evaluating the complete safety situation including
the pilot, ATC, TCAS and ASAS function to assess the ASAS safety requirements for each envisaged
ASAS application. The so-called « global collision risk » was estimated as the product of the absolutecollision risk by the failure rate of the relevant independent surveillance agents.
From the safety assessment it was concluded that the 3 selected applications all require a back-upsurveillance means :
• A dual channel ASAS function shall be required for Longitudinal Station Keeping and
Autonomous Aircraft applications,• Both ATC surveillance and a dual ASAS channel shall be required for Closely Spaced Parallel
Approach application.
2.2.1.2.2 Transition aspects
According to the WP5.5 Report, transition issues fall into two broad areas of investigation:
• The first is how to manage the transition from a mixed population of ADS-B and non-ADS-B
equipped aircraft to a population of fully equipped aircraft.• The second is how to best exploit the transition phase so that early benefits can be realised by the
airlines and ATS (Air Traffic Services) providers who make early investments in the ASAS and
related equipment.
Both these areas encompass both operational and technical issues, which have been addressed by the
EMERALD consortium, and are summarised below.
• Technical aspects
Ø Provision of current position of non-equipped aircraft to an ADS-B equipped aircraft
Passing the current position of all surrounding non-equipped aircraft to an ADS-B equipped
aircraft shall require the use of an additional technology like, for example, TIS-B (trafficinformation of the ground ATC system which is transmitted to equipped aircraft).
About this additional technology:
- A key problem to be addressed will be that of data fusion. Since the source data about non-equipped aircraft is unlikely to be in a standard ADS-B format (and may perhaps be
radically different - e.g. range and bearing data rather that latitude and longitude) either the
ground system or the airborne system on the ADS-B equipped aircraft must be capable ofmerging and comparing the two sets of data.
- It will be important to support an architecture that does not require modification of the non-
equipped aircraft avionics.
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Ø Provision and use of “intent” information
Most applications of ADS-B require knowledge of an aircraft’s position projected more thanone or two minutes into the future, and this implies knowledge of additional information about
the aircraft. This additional information can be divided into three groups:
- current aircraft state data, which includes things such as three-dimensional position andvelocity,
- short-term intent data, which includes data such as cleared flight level and cleared heading.
- medium-term intent data, which includes information on waypoints and on trajectorychange points, though not on the whole flight plan or 4-D trajectory.
The definition of what data from the last two groups may be included in the ADS-B message set
has not yet been agreed. Provisional definitions appear in the MASPS (Minimum AviationSystem Performance Standards) and in ADSP (Automatic Dependent Surveillance Panel)
documentation (without regard to the carrier medium for the data), and in SICASP
documentation (for a Mode S implementation). Standards for STDMA are even less welladvanced in this respect than those for Mode S.
The different definitions in the existing standards and documentation are not consistent.
Nor does the existence of a standard requiring ADS-B to provide a piece of informationnecessarily imply that that data will be available from current or future FMSs or data-buses.
It is important that, if early use is to be made of ADS-B applications, the data required to
support those applications is clearly defined. Once the requirement is understood, the necessaryaction should be taken to ensure that the data can be made available for broadcast by ADS-B,
taking into account realistic expectations of what current and future FMS’s and data-buses may
provide.
• Operational aspects
Ø Impact of the lack of international consensus.There is no international consensus at present about the most suitable bearer for ADS-B.
In the worst-case scenario, two competing systems will gain a strong footing in different parts
of the world, with airlines operating in both areas potentially having to equip with two sets ofkit (Mode S and VHF based) in order to take advantage of the different levels of service
provided within different regions.
At best, a lack of consensus is likely to delay implementation of ADS-B applications, asairlines and ATM providers alike adopt a ‘wait-and-see’ policy.
Ø Early ApplicationsSome European long haul operators have expressed some interest in ADS-B either for providing
situation awareness in areas where air traffic control is very limited (such as areas without or
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beyond radar coverage) or to solve problems at specific bottlenecks, where for example the cost
of being held below optimal cruise level for the duration of a long flight can be very high.
Simple applications like the use of longitudinal station keeping may allow a reduction in delaysby more efficient use of available airspace, without requiring a radical change in the current
ATM service. Applications of this nature are more likely to be readily accepted by both pilots
and controllers.Other applications may include use on the North Atlantic and other oceanic airspace (to
facilitate, for example, in-trail climbs or reduction in longitudinal separation) and use by
individual airlines to track accurately the movements of their own aircraft.
Ø Impact of a mixed ADS-B and non-ADS-B population on the ATM system
For many applications, there may be a ‘critical mass’ of equipped aircraft in a given local areathat make it feasible to implement an application or set of applications.
For example, in the case of the airlines operating out of hub airports, the population of equipped
aircraft must reach a certain level before the probability of two successive aircraft being ADS-Bequipped - and able to take advantage of local ADS-B based procedures – is great enough for
benefits to be measurable.
Other issues may include whether it is acceptable - or indeed desirable - to provide a‘differential service’ to aircraft equipped with ADS-B, allowing them, for example, to take
advantage of a ‘fast-track’ permitting reduced separations or reduced delays.
Ø Encouraging full equipage
Three points need to be considered:
- if benefits of early applications accrue to both ADS-B equipped and non-equipped aircraftalike, there may be no incentive for airlines to equip their aircraft ;
- it may not be possible for ATC to provide a ‘differential service’ to allow equipped aircraft
to make use of a ‘fast track’ ;- one solution could be a cost sharing arrangement between ATS providers and airlines.
2.2.1.3 Institutional Aspects
2.2.1.3.1 Operational Procedures
The EMERALD project proposes Operational Procedures for each of the 3 studied applications, which
are detailed in Annex C.
Operational procedures include general considerations like,
• The common denominator for ASAS applications procedures is that it will be a contract between a
pilot and a controller.
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• The controller will always ask the pilot before giving an ASAS application clearance. Before
accepting the clearance, the pilot should positively identify the other aircraft involved in the
separation he will have to assure.• In some cases, the controller might even inform the other involved aircraft about the planned
manoeuvre.
• Finally, the clearance will be limited in time or space, with instructions giving clearly the limits ofthe clearance.
Then each of the three selected applications is detailed according to the following points:• Actions and responsibilities taken by the pilot and the controller,
• Proposed actual separation between aircraft to be applied by the pilot during the procedure,
• Proposed new, or new usage of current, radiotelephony (R/T) phraseology,• Limiting factors which could affect the application of the procedure,
• Controller’s responsibility to maintain a monitoring function,
• Proposed contingency procedures,• Questions to answer.
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2.3 Review of TORCH project
Project overview
TORCH (Technical, EcOnomical and OpeRational Assessment of an ATM Concept AcHievable from
the year 2005) project started in January 1999 and is due to finish end of October 2000.
The main objective of the TORCH project is to define and assess the viability of a consolidated
operational concept based on the OCD (Operational Concept Document) target concept, coherent andcomplementary to the ATM 2000+ Strategy, and applicable in the medium term (10 years).
To achieve these objectives the TORCH project has adopted an approach that consists of threedifferent phases:
• Phase one identifies the definition of a draft Operational Concept deemed to be operative withinthe TORCH timeframe (i.e. 2005-2010).
• Phase two performs an assessment phase of the selected Operational Concept. This assessment isdone from three points of view: technical, operational and socio-economic.
• Phase three consolidates the draft Operational Concept into a final Operational Concept-. Thisconsolidation is based on the results obtained from the second phase.
At the time of the review, Phase 1 has been completed, Phase 2 is in progress, and Phase 3 has notstarted yet.
As an output of Phase 1, TORCH proposed a layered planning process, based on a more flexible use ofthe airspace and with a greater involvement of the ATM actors through the optimisation of the
available resources instead of constraining demand:
• The most significant TORCH proposal is to develop a Daily Operational Plan (DOP) through thedynamic use of CDM (Collaborative Decision Making). This plan is developed on the basis of the
information contained in the Strategic Plan, established one year in advance of the day of
operation. Until the day of operation, the layered planning process will continuously receive real-time updates to changing parameters (rolling planning), making the decision-making loop more
sensitive to the different stakeholder needs.
• Using CDM procedures, the DOP will be updated to create a comprehensive picture of the currenttraffic situation, taking into account real-time changes that can affect the stakeholders'
expectations.
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• The DOP process will improve the tactical planning phase, bridging the current gap between
planning (CFMU: Central Flow Management Unit) and execution (ATC). The increased accuracy
and dynamic planning enabled by the DOP will increase efficiency, in the sense of improved useof available physical capacity.
• Terminal Area Sequencing will match the planned approach and departure sequences to optimise
TMA (Terminal Manoeuvring Area) resources, through co-ordination between the stakeholdersinvolved in the process, such as airports.
• Progress towards a more autonomous aircraft. During the TORCH timeframe, responsibility for
Separation Assurance may be partially delegated to the aircrews of suitably-equipped aircraft.Conflicts will be detected by the ground system, which will propose conflict resolution strategies.
Hazard Assessment will be based on improved safety net functions: STCA (Short Term Conflict
• Aircraft operators will become more involved in planning and will make decisions together with
ATC and the CFMU. They will negotiate their plans during the planning phase and exchangeinformation with other stakeholders. Real-time data will be used to optimise fleet operations.
Schedules and routes will be closer to user preferences, improving the overall predictability of the
system.• Airport operations will be more integrated in the overall ATM process than at present. ATFM
measures and airport capacities will be linked during all planning phases. Co-ordination with the
en-route planning phase will support uninterrupted gate-to-gate operations.
Each of the concepts above are being assessed by Phase 2, on the operational, technical and socio-
economical point of view.
Documentation overview
The available TORCH documents (listed in Annex A) mainly deal with Phase 1 of the project, which
has a large scope and therefore contains very little information on the ASAS itself, and this
information remains quite general.
On the point of view of the ASAS, the only relevant document is WP4.3 Report. This document is not
yet finalised, but reflects the current status of work on a specific ASAS application: “Analysis of aconcept of Station Keeping Applicable to TMA”.
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Detailed review of TORCH documents
Only WP4.3 Report will be reviewed. In WP4.3 Report, “Station Keeping in TMA” concept has beenaddressed as a whole, i.e. including procedures, roles of pilots and controllers, and tools potentially
available to pilots and controllers.
Current status of the WP4.3 report allows the following CARE ASAS Activity One points to be
reviewed:
• Capacity and Efficiency issues are analysed,
• Operational Procedures are discussed.Based on the choice of a Time Separation criterion, TORCH proposes a concept of operation, and
introduces the notion of SK (Station Keeping) contract between the pilot and the controller:
2.3.1.1 ATM Performance Issues
2.3.1.1.1 Capacity and Efficiency issues
The TORCH project studies the applicability of Station Keeping to the ECAC (European Civil
Aviation Conference) high density airspace, where capacity and efficiency problems are stringent.
The objective of using Station Keeping in the TMA is not to augment the runway throughput (current
working practices at high density airports enable controllers already to work to the physical limits ofrunway capacity), but push back the capacity of approach sectors.
A by-product could be to support optimisation of scarce resources e.g. controllers. Busy airports
(especially where hubs have developed) may have part of their capacity wasted because terminalsectors are not able to deliver aircraft at the optimum rate offered by the platform.
The expected benefit is an increase of capacity through a better fluidity, predictability and regularity oftraffic, and a better accuracy on arrival times. The concept may enable also a reduction of actual in-
trail separations even though this aspect has not been considered as a major incentive. Indeed,
separation minima are defined by ICAO (International Civil Aviation Organisation) on the basis ofwake vortices constraints and radar performance. In practice, separation buffers may be added by ATC
to take account of controllers’ reaction time. A more accurate maintenance of separation with SK
could involve a reduction of these separation buffers.
Current TMA operations offer little flexibility to pilots in the management of flight, although aircraft
operators have their own requirements, e.g.:
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• landing as soon as possible i.e. decelerate as late as possible and follow the shortest trajectory
from the entry point in the TMA to the runway,
• optimising the descent (fuel savings, passengers’ comfort..) i.e. smoothing flight profilesdepending on aircraft characteristics (individual constraints integration).
Furthermore, controller’s activity in terms of aircraft speed control is very skill intensive and workload
demanding, whereas this activity deals with aspects of aircraft guidance that the pilot could properlymanage through the FMS.
The concept of Station Keeping in TMA shall improve the efficiency by:
• alleviating controller’s task currently dedicated to adjusting and monitoring the speed of
individual aircraft,
• whilst giving the pilot more autonomy (and responsibility) in the management and optimisation ofthe descent profile within the constraints of TMA control.
2.3.1.2 Institutional Aspects
2.3.1.2.1 Operational Procedures
Based on the choice of a Time Separation criterion, TORCH proposes a concept of operation, and
introduces the notion of SK contract between the pilot and the controller:
• Controllers would convey to pilots all information needed on “strategic rendezvous” along the
approach path. Pilots would be required to meet strategic 4D target fixes with the highest possible
accuracy.
• Between those 4D target fixes, pilots could be given some flexibility to adjust themselves the
speed profile within fixed tolerance margins depending on TMA traffic density and complexity.Those margins would be fixed by the ground on the basis of known reference flight profiles.
• 4D targets and tolerance margins would be agreed through SK contracts between controllers andindividual aircraft established prior to the SK descent phase.
• The pilot would be responsible for building the flight path within contracted margins. During theSK contract execution phase, controllers would be in charge of monitoring SK contracts.
The principle behind SK contracts is to anticipate this flow organisation in order to minimisecontroller’s instructions once SK streams are established. SK contracts would enable to translate
ground control constraints into individual flight constraints managed by pilots.
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Ideally, each aircraft would implement a “SK contract” previously agreed with ATC (a few minutes
before start of SK segment) whilst ATC would monitor its execution, thus intervening only in case ofa breach.
This is valid only if contracts are stable during the whole SK phase, or if they can be updated with asfew “manual” interventions as possible. A factor which influences the stability of contracts is the
TMA structure, fixed 3D routes being more “supportive” than a free route environment.
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2.4 Review of MAICA project
Project overview
The MAICA (Modelling and Analysis of the Impacts of Changes in ATM) project started in August
1996 and ended in March 1998.
The MAICA project aimed at evaluating, by using ATM simulation tools, the consequences on global
ATM performance (capacity, efficiency and safety) of various changes envisaged for AirspaceManagement, Air Traffic Control, airport and aircraft operations. It mainly addressed the medium and
long-term horizon (i.e. 2005 and beyond). This project did not cover all ATM aspects, but rather
focused on specific topics which provide sufficient insights and recommendations for future activities.
MAICA objectives were:
• to identify and describe some future significant changes which might affect the ATM,• to evaluate the impacts of a subset of these changes using simulations,
• to draw conclusions from the simulation results,
• to make a set of recommendations for future investigations and developments.
To cope with these objectives, the project was divided into four work packages:
• WP 1, Conceptual basis : selection and description of a set of envisaged changes in ATM,• WP 2,Simulation Definition: definition of the objectives of the simulations to be performed as
well as the scenarios and simulation criteria to be used to achieve these objectives, using the set of
changes selected in WP 1. Four simulation objectives are defined dealing with:Ø Autonomous aircraft,
Ø Dynamic sectorisation,
Ø Future Aviation Surveillance System,Ø RNP-1.
• WP 3,Modelling Platform : selection of relevant simulation tools to achieve the simulation
objectives defined in WP 2• WP 4, Evaluation: the four simulations are performed using the tools selected and adapted in
WP 3 in order to complete the objectives defined in WP 2. Through the analysis of their results,
the impacts of the changes on ATM are evaluated. As a second part, a set of recommendations isproduced.
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Documentation overview
The MAICA project issued one deliverable per work package. Regarding the CARE ASAS ActivityOne review, the most interesting document is the “Final Report” (WP4), which focuses on the results
of the evaluations. All MAICA documents are listed in Annex A.
Detailed review of MAICA documents/project
The MAICA project focussed its study of the Autonomous Aircraft Concept on three fundamentalquestions:
• How is the pilot workload impacted by the Autonomous Aircraft concept?
• What will be the traffic density in 2015, taking into account some assumptions on the autonomousaircraft concept?
• What is the best value of the look-ahead time in this context?
Regarding CARE ASAS guideline questions, the whole approach of MAICA project deals with
Capacity and Efficiency issues.
2.4.1.1 ATM Performance Issues
2.4.1.1.1 Capacity and Efficiency issues
A simulation tool, named MARS (Multiple Autonomous aiRcraft Simulation), implementing the
Extended Flight Rules (EFR) and the GEARS (Generic Algorithmic Resolution Service) ConflictResolution algorithm, was developed in order to:
• Measure the influence of traffic density on the complexity indicators chosen for MAICA (numberof ADS-B conflicts, number of solved conflicts, number of aircraft concerned by each conflict, ...)
• examine the impact of the variation in the look-ahead time parameter,
• compare several conflict resolution strategies in terms of number of solved conflicts and type ofresolution.
Modelling of traffic density in 2015A geographical area of interest was defined and a set of sub-areas was extracted from it.
These areas are presented on the map that follows.
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Latitude
Longitude-14 -4 6 16 26
34
44
54
64
74
1 - 1 1 - 2 1 - 3 1 - 4
2 - 1 2 - 2 2 - 3 2 - 4
3 - 1 3 - 2 3 - 3 3 - 4
4 - 1 4 - 2 4 - 3 4 - 4
Figure 1: Geographical area of interest divided in a set of sub-areas
Several simulations were run for each of these sub-areas using different 2015 traffic densities.
These densities are around two times more than those of 1996 and only flight levels above or equal to
FL 290 were taken into account. The traffic densities are defined using the « hourly weight » (HW) ofthe time that is simulated. The HW of an hour represents the percentage of the daily traffic that flies
during this particular hour.
For each area studied, several weights were used in order to represent this area at different times of the
• 7%: from 7 a.m. to 19 p.m. (normal/daily traffic),
• 10%: worst case (peak hour traffic).
Impact of traffic density on pilot workload
The idea was to establish a link between the traffic density and the complexity of situations
encountered by the pilot during the flight and, consequently, with the pilot workload.
The complexity of the situations is expressed through the following indicators:• average number of conflicts seen by the pilot per hour of flight,
• average number of actively resolved conflicts (density per million km2 and per hour of flight),
• average number of aircraft concerned in each conflict resolution.
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The observation of these three indicators versus the traffic characteristics shows that the complexity
increases with the traffic density:• Concerning the number of conflicts per aircraft, the increasing is in linear regression at least in the
limits defined by the work hypothesis.
• About the global number of conflicts, the increasing tendency seems to go to an « x² regression »but, in the worst case, this number is less than 450 resolutions per hour and per million km2 .
Regarding the pilot workload, it can be noted that:• the average number of conflicts that each aircraft must solve (actively) during each hour of its
flight is largely under 1 (equal to 0,7) in the worst case,
• the average number of conflicts detected by each aircraft in its ADS-B range during each hour ofits flight is relatively limited (around 1,8 detected conflicts in the worst case).
The worst case previously mentioned represents an aircraft density of more than 500 per 1 million km2
; it represents the traffic estimated during the peak hours for 2015 traffic estimation.
Variation of the look-ahead time
The second analysis carried out was dedicated to the study of the look-ahead parameter influence (i.e.
the length of the predicted trajectories broadcast by aircraft): several simulations were performed
using exactly the same scenario but with different values for this parameter (respectively 10, 8, 5, 3and 2 minutes).
The following measures were performed, which have to be consolidated by further experimentsinvolving pilots:
• The average numbers of conflicts detected and solved by aircraft increase slightly when the look-
ahead time is reduced from 10 minutes to 2 minutes.• The number of aircraft involved in conflicts is about the same for all the simulations.
• The difference comes mainly from the characteristics of the conflict resolutions carried out.
Indeed, the duration of a resolution is equal to the look-ahead time: this means that the result of aresolution is a trajectory conflict free during this look-ahead time.
• When this time is long, a resolution has less chance to induce another conflict (possibly with the
same aircraft) immediately after the one whose resolution is in progress.• Therefore, when the look-ahead time is equal to 2 minutes, the aircraft involved in conflicts
encounter on average more conflicts during their flight than when the look-ahead time is 10
minutes. This shows that the resolution duration is not long enough which brings more inducedconflicts.
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• When the look-ahead time is set-up to 2 or 3 minutes, the time between conflict detection and
resolution is very short (~20 seconds). This time could be slightly increased by tuning the TCRA
(Time to Conflict Resolution Activation) values.• The gain of performance induced when the look-ahead time evolves from 8 to 10 minutes is very
low.
Conflict Resolution Strategy
The objective of this last analysis is to compare three resolution strategies based on the EFR rules.These strategies correspond to three different working modes of the GEARS based algorithm
implemented in MARS i.e.:
• lateral, vertical and mixed resolutions allowed with an equal level of preference (LVM),• lateral resolutions mainly, vertical resolutions allowed only when it is the only way to have a first
class solution (L). Mixed resolutions are not allowed.
• lateral and vertical resolutions (LV) allowed with an equal level of preference. Mixed resolutionsare not allowed.
Two classes of resolutions have been considered :
• Class 1 resolutions: conflicts have been solved using a first class solution i.e. a solution allowingto return before the end of the resolution period to a trajectory leading to the exit point,
• Class 2 resolutions: conflicts have been solved using a second class solution (i.e. all solutions
which are not first class solutions).The same scenario was used to run one simulation for each of these strategies.
Simulations brought the following conclusions:• The differences between the three simulation results are quite small.
• The comparison of simulations LVM and LV shows that the gain due to mixed resolutions is
limited:Ø the increase in the first class resolution percentage is only 1% when comparing LV and LVM
and the order of magnitude of first class resolution probability is more than 90%,
Ø LVM allows reducing slightly the number of conflict resolutions requiring more than oneattempt (0.03% for LVM and 0.06% for LV) but, even for LV, these conflicts are very few.
• The LVM resolution produces more first class and second class solutions and more aircraft are
detected as intruders during the resolution process. This means that the information that could bepresented to the pilot would be more complicated. Therefore, the pilot would need more time to
choose and activate one of these solutions.
• The comparison of simulations LV and L shows that, in order to keep a ratio of first classresolution above 90% with a strategy aiming at using only lateral resolution, the vertical resolution
had to be activated for nearly 10% of the resolutions.
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• As a conclusion, mixed resolutions bring no real improvement in the resolution strategy. Even
when lateral resolutions are preferred, the computation of vertical solutions allows increasing the
percentage of first class resolutions.
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2.5 Review of Glasgow University Papers
Project overview
The ATM Research Group of the department of Aerospace Engineering at Glasgow University
focuses on mathematical modelling of methodologies that address the issues of the ICAO FANScommittee, among which include the ASAS. The ASAS research activities that are under way at
Glasgow University cover three operational aspects of Air Traffic Management:
• Conflict Avoidance in free flight airspace,• Transition management between the free flight airspace and conventionally controlled airspace,
• Air Traffic Flow Management in free flight airspace.
Documentation overview
Three papers issued by Glasgow University were provided by the consortium:• [5,1] Colin Goodchild, Miguel A. Vilaplana and Stefano Elefante “Co-operative Optimal
Airborne Separation Assurance in Free Flight Airspace”, USA/Europe ATM R&D
Seminar, Napoli 13th-16th June 2000.• [5,2] Colin Goodchild, Miguel A. Vilaplana and Stefano Elefante “Research explores
operational methods that could support a global ATM system”, ICAO journal April
1999.• [5,3] Colin Goodchild, Miguel A. Vilaplana and Stefano Elefante “Co-operative Optimal
Airborne Separation Assurance in Free Flight Airspace”, ICAO journal
November/December 1999.
Detailed review of Glasgow University documents/project
2.5.1.1 Technological Issues
2.5.1.1.1 Decision Support Tools
[5,1] proposes a new framework based on Distributed Artificial Intelligence to implement autonomous
airborne separation assurance in Free Flight airspace.Within the framework, conflicting aircraft form teams to co-operatively resolve conflicts, using
• an operational protocol for team formation,
• a dynamic programming algorithm for airborne centralised conflict avoidance planning.
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Operational protocol for team formation
Aircraft flying in free flight airspace are represented as autonomous intelligent entities (agents)embedded in a multi-agent system. Within this scheme, proximate aircraft form teams to establish a
plan to maintain safe separation with an agreed set of conditions.
The following protocol was defined for the formation of separation assurance teams:• Each aircraft monitors the tracks and communications of the surrounding aircraft to determine the
possibility of the violation of separation minima.
• When an aircraft detects a possible violation of separation minima involving itself and one ormore other aircraft, it broadcasts a message to the conflicting aircraft, and therefore becomes the
team organiser. The purpose is to form a team of aircraft that will co-operate to establish a
common resolution plan.• Then each conflicting aircraft replies to the team organiser, indicating whether it will join the team
or continue with its current intentions. The decision of each aircraft depends on its set of
conventions (conventions define the reasons for not joining a team, for example low fuel oremergency).
• Once the team has been formed, the team organiser designs a common resolution plan and
transmits this plan to the other team members. This plan provides a strategy to solve the predictedconflicts in a co-ordinated manner while taking account of the costs of the resolution for all the
members of the team.
• When the members of the team have received the resolution plan, they assess it against theirconventions and their current situation, and they communicate their imminent intentions to the
team organiser.
• If a team member decides to drop its commitment to the execution of the resolution plan, it isassumed it does so because it is unable to execute the actions assign to it in the plan.
[5,1] outlines that the detailed definition of this protocol will depend on the future technicalrequirements of inter-aircraft data communication systems (ADS-B and data-links).
Dynamic programming algorithm for airborne centralised conflict avoidance planning
The dynamic programming algorithm presented in [5,1] enables a the team organiser to design co-
operative strategic resolution plans for two-dimensional conflicts involving multiple aircraft.Resolution plans consist of a set of feasible speed control actions for each of the team members.
The algorithm provides avoidance strategies that minimise a global loss functional that considers
safety as well as economic costs.
The mathematical foundations of this algorithm are game theory, optimal control, motion planning in
robotics and dynamic programming.
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The conflict avoidance manoeuvres considered in the current version of the algorithm are speed
control actions. Extensions of the planning algorithm that provide co-operative resolution solutions to
three dimensional conflicts using horizontal and vertical manoeuvres have been examined but as yetnot reported in the open literature. Also a system in which co-operative conflict avoidance where only
the presence of proximate aircraft need be known has been evaluated through simulations and shown
to have a high probability of maintaining a given separation minima.
2.5.1.2 ATM Performance Issues
2.5.1.2.1 Transition issues
A method presented in [5,2] schedules inbound free flight aircraft along with conventionally equippedaircraft while maintaining an optimal, conflict and delay-free terminal airspace route to the destination
airport. The central feature of the proposed method is an extension of the concept of terminal area. The
extended terminal area concept incorporates a transition zone between free flight airspace and thepoint where aircraft commence their approach. The terminal area is a dynamically variable volume
with a radius established as a function of air traffic density.
The work on this concept focuses on the development of an algorithm called Constrained OptimalApproach Path (COAP). COAP automates the estimation of the flight path through the terminal area to
the selected entry point for the approach.
Using the current Glasgow Airport air traffic control model for the development of the COAPalgorithm, the basic free flight and terminal area transition element has been established and work is
currently under way in two other areas:
• The first is the definition of a criterion for the real-time determination of the dynamic radius of thefree flight and terminal area boundary as a function of air traffic density.
• The second area in the study is concerned with the computation of optimal routes from the free
flight and terminal area boundary to the approach entry point. The optimisation algorithm beingdeveloped is based on the aircraft speed adjustment margin and the standard descent profile and
cost function parameters associated with the free flight aircraft.
2.5.1.2.2 Flow Management
As presented in [5,2], the Glasgow Group developed a model for ATFM, which addresses theorganisation of air traffic management in free flight airspace and terminal airspace.
The main features of the ATFM model are :• a terminal area scheduling algorithm to optimise the flow of inbound and out-bound air traffic, and
to harmonise the flow of free flight air traffic and non-free flight air traffic ;
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• an en-route scheduling algorithm to organise and optimise at the flight planning stage the flow of
air traffic in free flight airspace to prevent the air traffic density rising above an unmanageable
level. The algorithm assigns an optimal free flight route that uses the aircraft trajectory parametersas the control variables;
• a routine to coordinate the above algorithms has been incorporated into the model.
Statistical methods are used to model and solve complex ATFM issues. The Glasgow Group’s ATFM
model includes the following operational aspects as stochastic processes: prediction of aircraft
movement in terms of arrival, take-off time and taxiing time, taking into account passenger behaviour,ground systems overload, equipment failures, weather factors, etc.
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2.6 Review of CENA ASAS work
Project overview
CENA has been working on the ASAS concept since 1995 when it proposed such concept as an
alternative way to the task given to the SSR Improvements and Collision Avoidance System Panel(SICASP) by ICAO on other uses of Airborne Collision Avoidance System (ACAS).
As an example of an ASAS application, the CENA proposed the ASAS Crossing Procedure (ACP) to
highlight how an ASAS application could be operationally used.
To examine the ASAS, CENA conducted several studies dealing with different ASAS applications
(e.g. ACP, autonomous aircraft operation) and other general issues of the ASAS concept:
• In order to study the operational impact of specific ASAS applications in the future European AirTraffic Management System (EATMS), the CENA defined a stepwise approach.
It proposed an assessment of the ACP, using the following method.
Ø Concept of ASAS operations assessment: to identify potential benefits and constraints forASAS procedures and logic refinement; to study the compatibility of ASAS applications
with Air Traffic Control (ATC) and ACAS.
Ø Feasibility assessment: to assess the pertinence of ASAS applications, the ASAS logicperformances and the ATC capacity and efficiency improvements
Ø Operational acceptability assessment: to validate the procedures and to assess the ASAS
application conformance to the pilot and controller requirements.
• A study into the Autonomous Aircraft application study,
Ø A free-flight autonomous and co-ordinated embarked solver has been implemented.Ø A technique that defined a fully distributed and reactive co-ordination of actions for multiple
mobiles was investigated and examined through experiments as a possible conflict detection
and resolution mechanism.
• Two studies, ASAS application independent, covering general issues have been done:
Ø An initial assessment of potential capacity improvement due to the ASAS concept
Ø A safety assessment to provide an initial framework of safety requirement analysis for ASAS
applications.
Parallel to this, the CENA has been involved in the definition of the ASAS concept at the ICAO level,
through the SICASP and the ADSP, and at the European level through the EMERALD project. These
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projects provide a high level overview and concept of the ASAS, identify potential ASAS applications
along with their benefits and constraints, and some potential ASAS issues which have yet to be
treated.
Document overview
The documents of the CENA are mainly composed of:
• articles presenting the works conducted within the CENA and which were presented at
international conferences,• internal reports,
• contributions prepared by the CENA in the framework of SICASP and ADSP.
The EMERALD project in which the CENA was involved is reviewed separately.
The list of the referenced document is detailed in Annex A
Detailed review of the CENA work
In the CENA review, the main inputs will mainly come from the documents produced exclusively by
the CENA.
Some high level requirements and issues provided by the SICASP and ADSP documents will be also
referenced when covering some of the points of the CARE-ASAS Activity One review.
The two broad classes of ASAS applications along with their benefits and constraints as proposed byADSP and SICASP in [ce13, ce17, ce19] are described in Annex B.
The different CENA studies cover many points of the CARE-ASAS Activity One review:
• CNS requirements: Initial CNS requirements are provided by ADSP and SICASP and by the
safety study.
• Decision Support Tools: An enhanced CDTI is proposed to support the ACP. As part of the
autonomous aircraft operation study, two conflict resolution mechanisms based on two differentstrategies are presented. At a higher level, some requirements concerning the ASAS design and
functions are issued from the operational concept assessment of the ACP and from ADSP and
SICASP.
• Capacity, safety and efficiency issues are covered through the feasibility assessment study of the
ACP, the theoretical capacity study and the safety assessment work.
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• Human factors are treated through the presentation of the operational acceptability assessment of
the ACP.
• Operational procedures contain the proposition of the ACP procedure.
• Responsibilities requirements are provided by the ADSP and SICASP documents.
2.6.1.1 Technological Issues
2.6.1.1.1 CNS requirements
Some initial airborne CNS characteristics have been provided by the various studies [ce12, ce16,
ce21]:
• It is assumed that airborne surveillance will rely on ADS-B techniques. Accuracy, quality,availability, integrity of the ADS-B data, update rate and surveillance range validation, capacity
versus performance need to be addressed.
• Since air-to-air data-link and air-to-ground data-link like Traffic Information Service-Broadcast(TIS-B) may also be used, the merging data from different sources is an issue.
• The use of ACAS surveillance data for ASAS functions should be investigated carefully so as to
maintain the independence of ACAS.• An air-to-air data-link is expected to support the necessary co-ordination for separation assurance
manoeuvres.
• No significant delay in air-to-air communication shall exist because aircraft will be flying inproximity.
• Intent information based on the navigation data are assumed to be exchanged between aircraft.
• The criticality required for an ASAS equipment will be dependent on the level of delegation forseparation assurance
2.6.1.1.2 Decision Support Tools
Enhanced CDTI
As part of the ACP study, the CENA proposed in the paper [ce5] an initial enhanced CDTI to support
the pilot to handle the ACP.
No process of conflict detection is performed on-board since the controller identifies the problem. The
enhanced CDTI provide the pilot with only graphical information to help him to assume the ACP. No
mechanism of on-board automatic resolution is provided.
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• This CDTI is based on aircraft position information.
• It describes the situation with respect to the aircraft in conflict through a relative speed line.• It displays a 8 nm circle centred on the aircraft position.
Conflict detection and resolution logic based on force fields
Context
The CENA supported a two-year study to investigate and experiment a technique previouslydeveloped at the ONERA. This technique defines a fully distributed and reactive co-ordination of
actions for multiple mobiles. This technique was studied as a possible airborne separation assurance
system ensuring co-ordination of avoidance manoeuvres.
The force field technique
The technique used is an extension of the potential field technique used in robotics for real-timeobstacle avoidance.
The robot (mobile) is a particle moving under the influence of potentials generated by the goal and byobstacles. The goal produces an attractive potential that pulls the robot towards it, while the obstacles
produce repulsive potentials which push the robot away from them. The negative gradient of the
resulting potential defines the (artificial) force to be applied to the robot. The repulsive potential isbasically a decreasing function of the current distance between the mobile and the obstacle.
To overcome the steady state problem induced by this technique, a new force is introduced whichshould create an avoiding action to induce a move around motion, as opposed to the fleeing action
induced by repulsive potential. This new force would lead the aircraft to bypass the intruder. The
direction for the new force is any direction that could induce a by-pass movement. The velocity vectoris used as a preferable direction.
In case of an encounter involving two co-operative aircraft (i.e. using the same technique), the notionof coupled sliding forces is introduced. Both sliding forces applied to the reference aircraft and to the
intruder are symmetrical which ensure complementary of actions without explicit co-ordination
between both aircraft.
Thus, this technique defines a decentralised and reactive co-ordination mechanism: the forces are
calculated for each aircraft, only based on information needed by the potential and by the projectionvector.
Application to air traffic
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This technique of force fields is applied as an airborne logic of conflict detection and resolution. This
logic is presented, in particular how the notions of repulsive and sliding forces can be applied to the
conflict detection and resolution.
• Conflict detection
The risk of conflict between a reference aircraft and an intruder can be expressed as a repulsivepotential. Usually, the parameter used for repulsive potential is the current distance between the
mobile and the obstacle. Various improvements of the potential computation were performed, e.g.
the introduction of an elliptic distance, of a volume of protection as mentioned in [ce4].In particular, to handle high speeds and provide anticipation the Closest Point of Approach (CPA)
is used, by extrapolating the current positions of the mobiles to the point of minimal distance.
In addition, maximal and minimal look ahead times are introduced along with an upper and lower
thresholds of distance to allow a gradual progression in the risk prediction.
Therefore the prediction of conflict is based on the combination of two parameters: (1) thedistance at CPA, (2) the time until CPA.
The potential varies from zero where the risk is null to unity where the risk is maximum.
• Conflict resolution
The conflict resolution consists in determining the direction of the force to avoid conflicting
intruders. The direction can be defined as a sum of the sliding forces corresponding to eachintruder. In case of a co-operative intruder, the two sliding forces (of the intruder and of the
reference aircraft) are defined as a pair of sliding forces. As the CPA is used for the conflict
detection, the position at CPA is used to determine the avoidance manoeuvre direction.
So, the vector of direction takes into account:
• the direction which increases the distance at CPA,• the limitations of movements (e.g. resulting from cinematic and environmental constraints).
These limitations are modelled by a constraint vector.
Therefore the projection vector results from the combination of :
• The relative position at CPA and,
• The relative constraint vector.
Additional studies presented in the documents [ce6, ce9, ce10] were performed to compare
different airborne conflict resolution strategies, using a different formulation of forces. Theresolution strategies were:
• repulsive force based on current distance,
• sliding force based on current distance and using velocity vector as preferable direction,
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• repulsive force based on distance at CPA.
The resolution strategy mode is either a prioritised mode or a co-ordinated mode. The results
obtained highlight that the co-ordinated mode was more efficient than the prioritised mode andthat the force based on CPA gave similar results to the sliding force.
Functional architecture of the module of separation assuranceThe six main functions of the logic implemented in the module of separation are presented below. This
module was integrated in a platform to perform validation tests.
• Determination of the status of the reaction: for each couple (reference aircraft, intruder) it
determines the reaction of the reference aircraft and the intruder; either the reaction is passive
(without reaction) or co-operative (and will be based on the same avoidance logic).• Detection of the risk of conflict of which the objective is to predict the risk of conflict between an
aircraft and the intruders. The risk is predicted for each couple (reference aircraft, intruder).
• Detection of the constraints which aims at expressing through a vector, the limitations of thereference aircraft movements resulting from cinematic and environmental constraints. This
constraint vector can defined as the negative gradient of a potential of constraint.
• Determination of the type of resolution: According to the geometry of each encounter, either theresolution is a by-pass movement or a go-away movement.
• Resolution of the conflict which objective is to determine a direction to avoid conflicting
intruders. The multi-intruder resolution is obtained through resolutions by couple, by summing allthe avoidance vectors of each couple.
• Computation of the avoidance manoeuvre: In case of a risk of conflict, the force defined to avoid
the intruders is translated into an indication of manoeuvre which is presented to the pilot or sent tothe FMS.
Overall characteristics of the logicThe overall behaviour of the mechanism is similar to the ACAS one and is described as follows:
• When a risk occurs the logic issues an avoidance manoeuvre advisory (corrective mode).
• Once the real risk is eliminated, but a potential risk still exists, the logic proposes a progressiveand partial resumption of navigation (preventive mode).
• Once there is no risk of coming into conflict, the logic generates a “clear of conflict”.
For each intruder, the information, broadcast by each aircraft, required is:
• The relative position and velocity vector
• The status (passive or co-operative)• The constraint vector if co-operative
The logic is basically incremental and continuously updates the advisory at each cycle.
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The logic is capable of handling both passive and co-operative multiple aircraft intrusions.
Theoretically the coherence of manoeuvres between co-operative intruders is ensured without explicitco-ordination. However, imprecision may induce conflicting manoeuvres, in that case, a co-ordination
mechanism has been introduced.
Experiments
Some experiments were performed to:
• Tune the parameters of the logic (in particular thresholds of distance and time) and evaluatestatistically the performances
• Analyse qualitatively the behaviour of the logic in typical encounters.
The statistical evaluation was divided into two steps:
• Safety issues: the logic must resolve a maximum of conflict but should trigger avoidance
manoeuvre only when necessary.• Cost issues: In order to reduce deviations while not inducing new conflicts, when the logic has to
switch to preventive mode and generate the “clear of conflict”.
The following results were obtained:
Safety issues:
• The rate of resolved conflicts increases with distance threshold and look ahead time, but the rate offalse alarms also increases with the rate of resolved conflicts.
• Beyond a certain value, a high look ahead time does not provide any benefit in term of rate of
resolved conflict.• From a qualitative point of view, the maximal rate of resolved conflict is obtained with a false
alarm per four conflicts detected.
Cost issues:
• A too early resumption of navigation provides returns into conflict which nevertheless are solved
by the logic.• It is possible to obtain a “reasonable” cost inferior to the maximum cost admissible.
Qualitative analysis:• The logic was capable of handling the 84 typical encounters defined by the CENA.
• It has underlined the importance of the behaviour during the preventive phase.
• It has highlighted that the intent of aircraft should be available to reduce the false alarms.• The logic is able to handle multi-intruder encounters.
Conflict resolution algorithm
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As part of the autonomous aircraft operation, the paper [ce7] proposes an algorithm for an autonomous
embarked conflict resolution with a co-ordination mechanism. No mechanism of conflict detection isprovided.
The main hypotheses and characteristics of this solver are described hereafter.
• All aircraft are supposed to be able to broadcast:
– their current position– their predicted trajectory over the next 5 minutes
– their exit point of the free-flight airspace
• All aircraft are supposed to be able to receive current position and trajectory information fromother aircraft.
• The solver should guarantee a 5 minutes conflicts free trajectory to each aircraft.
• The co-ordination between aircraft involved in the conflict is assured through the definition of aglobal resolution order between conflicting aircraft.
• The global resolution order provided is based on a token allocation strategy, which supposes the
existence of a total priority order relation between aircraft. Tokens are virtually exchangedbetween aircraft according to their priority.
Initially, the simple order based on transponder numbers was used as a total priority order. But
simulations allowed to define a more efficient total priority order: an aircraft that is manoeuvrefree has a lower priority order than an aircraft that has already started a manoeuvre. The
transponder number is used to determine the priority between two manoeuvre free aircraft or two
aircraft manoeuvring.• The mechanism of resolution, which consists in finding a new trajectory to avoid several already
fixed aircraft trajectories, is based on an A* algorithm. The A* algorithm finds the shortest path in
a tree, given an initial state and a set of final states. It uses a “best first” strategy to develop eachnode. The best node is the one that provides the lowest expected cost.
Initially, the cost function used for the algorithm was only the trajectory length but simulation
results suggested that the cost function of the A* should also take also into account the efficiencyof the manoeuvre.
Finally, simulations brought the following conclusions. The solver is:• Relatively low cost as most hypothesis are quite weak,
• Mathematically provable,
• Efficient in upper airspace;• As trajectories are guaranteed conflict free for at least five minutes, a transient failure would not
have a disastrous effect,
• The manoeuvre model is classical and easy to implement,
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• Could be progressively put into service by defining free flight airspace and gradually extending
them.
ASAS requirements and issues
As part of the assessment of the operational concept of the ACP, simulations have been performed toevaluate the ACP logic. A simplified conflict detection and resolution representing a basic ACP logic
has been implemented in the CENA test-bench as explained in [ce8].
From these evaluations of the ACP logic performance, some issues related to ASAS requirements
have been identified:
• Horizontal versus vertical conflict resolution taking into account ATC and ACAS IIcompatibility constraints
• Discrete conflict resolution for pilot validation versus reactive automatic conflict resolution for
minimum trajectory alteration• Risk of disruptive conflict detection without aircraft selected parameters processing
• Risk of loss of separation with conflict detection without intents processing
• Risk of inefficient conflict resolution without taking into account navigation constraints• Risk of incompatibility with ATC or ACAS in case of reduced airborne separation standard.
In addition, some general ASAS requirements are provided by the ADSP and SICASP documents[ce15, ce19]:
• The on-board architecture may have to be adapted, for example new FMS or auto-pilot functions.• Algorithms for conflict detection and resolution and separation assurance manoeuvres shall be
studied including compatible resolutions between aircraft.
• ASAS resolutions shall be compatible with ACAS resolutions.• There may be a requirement for exchange of flight information between aircraft and/or the ground.
• When designing a traffic display for ASAS applications, there is a need to investigate whether
ACAS and ASAS display representations could be safely combined on a common CDTI.• ASAS and ACAS might share some components but the loss of the ASAS functions shall not be
detrimental to the ACAS function.
2.6.1.2 ATM Performance Issues
2.6.1.2.1 Capacity and efficiency issues
Two ways to assess the capacity improvements are proposed.
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• In order to assess the feasibility of the ACP, the CENA has planned a cost/benefit analysis using
fast-time simulations. These simulations are intended to assess more in detail the ACP logic
performance and the possible improvement of ATC capacity and efficiency.
Details concerning the simulator and the measured indicators are explained in [ce8]. Simulations
have not been done yet.
• [ce11] proposes a theoretical assessment of the sector capacity improvement due to the ASAS
concept.
Based on the MBB (Messerschmitt Bölkov Blohm) method which models the sector capacity and
on the sector workload intensity definition proposed by Andrews and Welch* the paper provides away to compute the Sector Capacity Improvement (SCI) due to the ASAS.
Quantitative results show that the more applicable the ASAS concept is (which depends on thepercentage of the ASAS equipped fleet, on the probability of use of the ASAS and on the
efficiency of the system), and the less complicated the clearance of delegation is, the higher the
SCI is. Nevertheless, it shows that the increase of the SCI is limited to 12,2 % in an optimal case,which can be explained by the assumptions made.
*J. Andrew, D. Welch, “Workload implications of free flight concepts”, USA/Europe ATM R&DSeminar, Saclay, 1997
2.6.1.2.2 Safety
As presented in [ce12], an operational safety assessment work has been performed to provide an initial
framework of studying ASAS applications in term of safety. The purpose of the work is to highlightthe major criticality issues and also the possible mitigation’s that need to be taken into account to
support safe ASAS operations.
The work used, as a basis, the operational safety assessment methodology developed by RTCA SC189
and EUROCAE WG53 and adapted it for the context of the ASAS.
The successive steps proposed by the methodology in order to identify the required elements for the
ground and the airborne segments are summarised hereafter:
• A description of an operational environment of ASAS applications, which aims at describing how
and in which context the application is supposed to operate.
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• An operational hazard analysis (OHA) which consists in identifying, classifying and establishing
the likelihood of the different hazards (e.g. system and human failures and human errors) along
with the identification of the avoiding and mitigating factors associated.• An allocation of safety objectives for ASAS operations.
Some examples of operational hazards analysis (OHA), hazard likelihood analysis and allocation ofsafety requirements concerning the ACP, the enhanced visual approach and the conflict detection and
resolution application are provided in Annex D.
From these different steps, requirements concerning the air side and the ground side should be
obtained.
In the context of the study, initial requirements concerning the ASAS characteristics and the role of
the ATC and ACAS II were stated.
In addition of those already mentioned in the section 2.6.3.1 “CNS requirement” the followings safety
requirements are provided:
– The development of alerting system for airborne separation monitoring has to be investigated.
– The sharing of responsibilities between controller and pilot has to be clearly defined.
– Different risk mitigation strategy for ATC intervention may be developed depending on therelationship between airborne separation minimum applied by the flight crew and the ground
separation minimum used by ATC.
– The use of ACAS as a mitigating factors for some hazards has to be carefully investigated sinceACAS is not designed as a critical airborne element.
– The compatibility between the airborne separation minima and the avoidance collision logic may
be a limitation for the reliance on ACAS II mitigation.
2.6.1.3 Human factors
As explained in the paper [ce8], as part of the ACP study, real-time simulations are foreseen to assess
its operational acceptability. They should permit to validate the procedure and to assess the ASAS
application performance.
The objectives of the evaluation are the assessment of:
• The operational need for the ACP• The improvement of the pilot’s traffic awareness and the coherence with the controller image of
the traffic
• The adequacy of the ASAS functions on board and the CDTI facilities
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• The efficiency of the ASAS functions on board
• The compatibility with Air Traffic Control
• The adequacy of the contingency procedure during the simulation of degraded situations.
The simulation results are not yet available.
2.6.1.4 Institutional Aspects
2.6.1.4.1 Operational procedures
The CENA proposes an operational procedure for the ACP which is detailed in [ce5, ce14].
This procedure would be very similar to visual separation clearance. The main difference is that this
procedure could be applied under Instrument Meteorological Conditions (IMC).
The procedure overview is the following:
• It requires common agreement between the pilot and the controller for the object of the contract,
i.e. the crossing, and for its duration.• During the ACP clearance, the pilot is responsible for maintaining the standard airborne separation
from other air traffic.
• The conflicting aircraft is informed by the controller and is supposed not to deviate from itscurrent clearance.
• When the ACP is performed, the pilots reports to the controller who issues an after ASAS
clearance to allow the normal IFR continuation of the flight.
A phraseology associated to this procedure is proposed in [ce5].
2.6.1.4.2 Responsibilities issues
The ASAS concept implies new share of responsibilities between the ground and the air which need tobe clearly defined due to the legal implications that can be derived from it.
ADSP and SICASP, through the documents [ce13, ce19] proposed two levels of responsibilities whichare described hereafter with the role of the ground for each level.
• Limited transfer of responsibilities where separation responsibilities remain on the ground, exceptunder specific circumstances limited in time, space and complexity of the traffic. The flight crew
will take responsibilities for maintaining separation within the boundaries of ATC clearance.
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Such responsibilities could be introduced in current ATC organisations, no dramatic changes in
the role of ATC will appear.
• Extended transfer of responsibilities where separation responsibilities are placed on the air.
In that case, the role of the ground system could be to:
– Provide flight information service– Provide strategic ATC including flight plan de-confliction, traffic density and complexity
management
– Control transition zones between airspace with extended transfer of responsibilities andairspace with limited or no transfer of responsibility
– Support contingency procedures as a back-up through ground surveillance for example
– Provide alerting service.
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2.7 Review of the FREER project
Project overview
The EUROCONTROL Freer Route Experimental Encounter Resolution (FREER) project
investigates the concepts of delegation of separation assurance to the aircraft, followingEUROCONTROL’s ATM2000+ Strategy.
The FREER project started in 1996 and is still on going.
The objectives are divided over two time frames, each time frame being addressed by two different
sub-projects, FAST (previously named FREER 1) and EACAC (previously named FREER 2).
FAST (Full Autonomous Separation Transfer) investigates the concept of autonomous aircraft in
free-flight airspace, or where ground infrastructure is not available, by 2015.It considers that an aircraft operating in autonomous mode is fully responsible for assuring separation
with other aircraft, restricted areas, weather and ground.
Through its study, FAST focuses on:
• the technical feasibility of ADS-B and data-link technologies
• the rules of the air as well as the procedures to be applied in Autonomous Aircraft regime• the development of an Airborne Separation Assurance System demonstrator.
As part of the investigation towards autonomous aircraft mode, live trials took place from October1998 to the beginning of 1999 (this live trial project was previously named FREER3).
Commercial aircraft were equipped with the FREER3 ASAS prototype, derived from the FAST ASAS
demonstrator. This ASAS prototype was implemented by an airborne system called the MMI5000which was modified by the incorporation of the ASAS function. Position reports and trajectory intents
were exchanged between aircraft using the STDMA VDL Mode 4 technology. Trials were organised
in Germany, as part of the JANE project, and in Sweden.
The objectives were to get early comments on autonomous aircraft operation feasibility.
EACAC (Evolutionary Air-ground Co-operative ATM Concepts) investigates the concept of
limited delegation of separation assurance to the cockpit in managed airspace.
Starting from the analogy of visual clearances, EACAC studies the delegation to the pilot of sometasks related to separation assurance. EACAC targets near term applications – typically 2005 – taking
place in current ATC organisations while at the same time proposing long term developments.
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EACAC proposes a pragmatic and straightforward initial concept which aims at respecting roles and
working methods of controllers and pilots. Therefore, EACAC relies on two key elements:
• limited delegation: The controller keeps the initiative and the overall authority on trafficmanagement. The task delegated to pilot is limited to the monitoring up to the implementation of
solution.
• flexible use of delegation allowing each controller to select the most appropriate delegation levelfor each situation, and enabling an incremental practice to progressively gain confidence.
EACAC considers two classes of application:• Crossing and passing applications in en-route airspace.
• Sequencing operations – in-trail following and traffic merging – in extended Terminal
Manoeuvring Area (TMA).
EACAC focuses on:
• The definition of the concept, through the definition of procedures and phraseology,• The definition of on-board assistance to support the pilot in the delegation process,
• The evaluation of possible gains which could be obtained from this concept through real-time
simulations.
Document overview
The documents of FREER are composed of articles, which were presented at international conferences
and reports about experiments.
The list of the documents is provided in Annex A.
Detailed review of the FREER project
Through these two sub-projects, FREER covers many points of the CARE-ASAS Activity One
review.
• CNS requirements: Both of the projects propose CNS requirements:
• Advanced CNS requirements for FAST• Minimum CNS requirements for EACAC which adopts a pragmatic approach.
• Decision Support Tools: An ASAS prototype implemented in a cockpit simulator is presented byFAST, and initial requirements for an enhanced CDTI to support limited delegation is proposed by
EACAC.
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• Human in the loop experimentation: Both of the projects have done real-time experiments to get
feedback on the feasibility of both concepts. These experiments involved pilots for FAST and
pilots and controllers for EACAC. Live trials were performed within the FREER3 project.
• Operational Procedures: FAST provides procedures and rules of the air to be applied for resolution
of encounters in autonomous aircraft mode. EACAC provides initial procedures concerning thelimited delegations.
2.7.1.1 Technological Issues
2.7.1.1.1 CNS requirements
FAST CNS requirements
The assessment of the technical feasibility of ADS-B and data-link technologies for the autonomous
aircraft mode issued some CNS requirements.
These requirements, described hereafter, come from both the rules of the air requirements and the
ASAS requirements.
• ADS-B requirements:
− ADS-B range is about 120-150 Nm− ADS-B message contains:
1. Aircraft identification: call-sign, category and address
2. State vector: position, altitude, source of altitude, position uncertainty category andvelocity vector
3. Tactical parameters: Trajectory Change Point (TCP), turn rate, target altitude and
emergency/priority status.• Data-link message:
Aircraft-to-aircraft messages are available to allow the exchange of additional trajectory information
(e.g. TCP) and the acknowledgement of reception and priority.• Broadcast message:
Two kinds of broadcast messages are available which contain:
– identified constraints on the current trajectory e.g. encounters,– intention of change
EACAC requirementsEACAC relies on minimum assumptions for CNS facilities and assumes that position and velocity of
the aircraft transmitted through ADS-B or TIS-B are sufficient. Trajectory intent information is not
required but could be used to increase the domain of applicability.
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2.7.1.1.2 Decision support tools
Both FAST and EACAC studies propose some ASAS capabilities appropriate to the tasks delegated to
the flight crew.
FAST on-board ASAS capabilities
The autonomous aircraft mode requires that all aircraft are equipped with an FMS which predicts thetrajectory and guides the aircraft accordingly.
FAST developed a prototype ASAS providing the following on-board functions required to handleautonomous aircraft operations:
− CDTI to depict traffic information relative to the aircraft (own-ship)
− Conflict detection and situation display allowing the pilot to visualise potential conflictsbetween its own aircraft and surrounding ones
− Priority determination when a conflict occurs
− Conflict resolution and resolution advisories allowing the pilot to resolve conflicts in twodifferent modes: manual, automatic.
The characteristics of these different functions, as proposed by FAST in [fr7] are summarised as:
• CDTI: The traffic information is displayed on the ND and uses TCAS derived symbols. The
information provided concerns aircraft situated in the ADS-B range around the own-ship aircraft,and consists of the relative position, the track vector, the call-sign, the flight-level and a vertical
trend arrow indicating the attitude of the aircraft. The pilot has the ability to remove all
identification information.
• Conflict detection: The conflict detection algorithm is derived from the Highly Interactive
Problem Solver (HIPS) concept and is based on the 4D trajectory intent information received fromall aircraft.
Any loss of separation occurring beyond a certain look-ahead range is ignored.
• Conflict situation display: the conflict situations are converted graphically into forbidden zones
and are displayed on the ND. These forbidden zones are of two types:
Ø Conflict zone: area corresponding to the portion of airspace where the separation between twoaircraft trajectories is infringed.
Ø No-go zone: area corresponding to the portion of airspace where the separation between the two
aircraft trajectories could be infringed due to a trajectory change.
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• Priority determination: when a conflict is detected, priorities are assigned to aircraft involved in
the conflict to determine which aircraft has to manoeuvre.This priority assignment is done through the use of Extended Flight Rules (EFR) which are
developed more in detail in section 2.7.3.4.1..
• Conflict alerts: conflicts are indicated to the flight crew through the following:
Ø An aural alert: a synthetic voices announces “Separation loss” once immediately after detection.
Ø Change of the own ship symbol: the symbol is filled in with yellow if the aircraft has to moveand simply surrounded by a white square otherwise. The same rule is applied for the other
aircraft symbol.
Ø Change in the display of forbidden zones.− All forbidden zones (conflict and no-go zones) are showed if the own ship has to manoeuvre.
The trajectory of the conflicting aircraft is displayed as white dotted line.
− Only the conflict zones are displayed if the own ship does not have to manoeuvre. Thetrajectory of the conflicting aircraft is displayed as yellow dotted line.
On both trajectories, tick marks at 1 minute intervals indicate the remaining time before the
beginning of the predicted loss of separation.
• Conflict resolution and resolution advisoriesTwo resolution modes are provided to the pilot: an automatic mode and a manual mode.
− Manual: the pilot inserts new way-points in the current trajectory via the FMS through its
Control Display Unit (CDU), or via direct manipulation of trajectory on the ND through apointing device.
− Automatic: A solver provides computed solutions designed to solve the conflict and to avoidno-go zones.
The solver is activated on request, through an arrow button (left or right, as preferred by the pilot)situated on the ND, the best solution in the selected direction is then displayed and can be
activated by the pilot if he considers it acceptable. The proposed trajectory is still modifiable by
the pilot. The no-go zone turns to grey indicating that the solution is conflict free.The time difference of Estimated Time of Arrival (ETA) between the proposed and the original
trajectories is displayed on the ND to inform the pilot of the “cost” of the proposed trajectory.
Two different conflict solvers have been implemented in the FAST prototype.
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Initially, as mentioned in the documents [fr2, fr6], the conflict solver was based on the force
fields techniques. The force field techniques is described in detailed in Section 2.1.3.2, part
“Conflict detection and resolution logic based on force fields”.The slight adaptations of thistechnique to the FAST context is summarised in Annex C.
Ø Secondly, the conflict solver which has been implemented is the Generic AlgorithmicResolution Service (GEARS) algorithm. This conflict solver has been used for the human-in-
the-loop experimentation.
EACAC on-board assistance
EACAC investigates the on-board assistance tool required by the pilot to handle limited delegations.
EACAC relies on minimum ASAS capabilities, and assumes that only an enhanced CDTI (denoted
CDTI++) is required, the connection to the FMS or to the auto-pilot is not required.
Hereafter, some requirements for an enhanced CDTI (CDTI++) proposed in [fr9, fr10] are
summarised.
The level of task delegated to the pilot can range from monitoring up to the implementation of a
solution, therefore two assistance functions are required to support these different tasks:• monitoring separation function, including identification of specific events typically the “clear of
target”
• implementation of solution function, i.e. capability to identify of an appropriate manoeuvre(specified by the controller).
To comply with these functions, three levels of assistance are proposed:• “Actual”: indicates the separation value based on current flight parameters
• “Target / What if”: indicates the separation value based on the target values of flight parameters
selected on the auto-pilot (heading, speed or vertical speed)• “Scale of separation”: indicates the separation value for a range of flight parameters (heading or
speed).
The definition of the separation parameter depends on the application and is based on:
• Closest Point of Approach (CPA) for high closure rate applications, e.g. for crossing applications
• Sliding Future Point (SFP), i.e. predicted point x minutes in advance, for low closure rateapplication, e.g. longitudinal station-keeping.
The Enhanced CDTI (CDTI++) includes Enhanced ND (ND++) and Enhanced PFD (PFD++).
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• The ND++ is devoted to the understanding of the situation, and thus indicates: position of the
target aircraft, actual value of the separation parameter, along with time associated (if applicable).
• The PFD++ is devoted to the manoeuvring for ensuring separation, and thus indicates: actualtarget and range of possible values of the separation parameter, along with time (if applicable).
Global ASAS framework
FREER proposes in the document [fr13] a framework for analysing the different studies which were
carried out in the domain of delegation of separation assurance to the cockpit. This framework is basedupon a proposed new dimension – the notion of “level of delegation”.
This article proposes to link the different studies from an operational perspective to a more theoretical
point of view, and addresses:• The operational aspects with the limited, extended and full levels of delegation which are
presented.
• The cockpit aspects: Different levels of on-board assistance are presented and classified from thesimplest to the more complicated. It is underlined that they are closely linked to the operational
concept and through these to the different procedures and delegated tasks.
• The system aspects, mainly the conflict detection and resolution issues which are analysed underthe following points:
– The levels of surveillance of information required to support the applications.
– The resolution strategy, typically “reactive” or “planning” with the variants centralised,distributed or prioritised.
– The co-ordination strategy among aircraft, typically “simultaneous” or “sequential”.
– The co-ordination domain, i.e. the set of aircraft which has to be considered for co-ordination.
2.7.1.2 ATM Performance Issues
The following section summarises the benefits in term of efficiency, safety and capacity, as proposed
in [fr9], which can be reasonably expected from the limited delegation:
Efficiency for the delegated aircraft:
• Non optimal manoeuvres ordered by controller to ensure safety with uncertain trajectories may be
avoided by delegation• The manoeuvres managed by the pilot may be more efficient (e.g.; less time on intermediate level,
less heading deviation)
• If proven that smaller separation minimum can be applied, closer passing/crossing capabilitieswould slightly increase efficiency.
Safety:
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• a medium term situation awareness will be provided to the pilot.
Efficiency for the non-delegated aircraft:• Assuming that delegation will provide more availability for the controller (due to a workload
reduction and regulation), this availability could be converted in efficiency by spending more time
on the non delegated traffic and problem, in order to work out more elegant or efficient solutions.
Capacity:
• Assuming that delegation will provide more availability for the controller, this availability couldbe converted into capacity by the control of more traffic.
The real-time experiments should allow to have results concerning these expected benefits.
2.7.1.3 Human-factors
Within autonomous aircraft concept evaluation, two human-in-the-loop experiments involving pilots
have been performed: the FREER3 trials and the FAST real time simulations.
FREER3 live trials
The live trials took place from October 1998 to the beginning of 1999. They involved the airlinesDLH, SAS, OLT and the European organisations DFS, Swedish CAA, LFV and Carmenta.
Commercial aircraft were equipped with the FREER3 ASAS prototype, derived from the FAST ASAS
demonstrator. This FREER3 ASAS prototype was implemented in the airborne device named ManMachine Interface 5000 (MMI5000), developed in the framework of the North European ADS-B
Network (NEAN) trials. To do this, the MMI5000 has been upgraded to include conflict detection
(based on HIPS algorithm), Extended Flight Rules (EFR) and a virtual way-point resolution.As the aircraft were not equipped with flight management system (FMS) a simplified form of
trajectory prediction based on the aircraft’s flight plan was added in the MMI5000 software. To ensure
flight safety, vertical separations were ignored by the software.Position reports and trajectory intents were exchanged between aircraft using the STDMA VDL Mode
4 technology.
The objectives of these live trials, were to:
• Evaluate the STDMA VDL Mode 4 technology
• Collect opinion about the FREER3 autonomous aircraft procedures, as well as to hardware andsoftware issues.
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The FREER3 trial conclusions about procedures were issued from questionnaires and interviews and
are presented in the document [fr14]. They can be summarised as follows.
• Conflicts need to be solved on a graphic page (like a moving map or navigation display format)
and not on an alphanumerical flight plan page.
• The trials procedures were found appropriate by the aircrews.• The aircrews were supportive of future operations with trajectory negotiations as in FREER3.
• In a future flight management system with the possibility of performing conflict detection and
resolution (CD&R), the virtual way-points should be positioned as a modification to the activeflight plan.
• A mouse or a joystick is preferred to touch screens for graphical modification of way-point
handling.• The countdown clock showing time left to resolve a potential conflict is a great help, but may also
be an added stress factor.
• The trajectory of a conflicting aircraft is necessary to understand the conflict.
Concerning the hardware and software conclusions, it has been mentioned that the positioning of the
CDTI must be in or very close to the pilot’s primary field of view and, when possible, integrated intothe Navigation Display (ND). The colours, colour coding and readability on the CDTI were reported
to be good.
FAST experiments
Following the live trials, FAST set up a new experiment to gather more data on autonomousoperations from an aircraft perspective, specifically on the acceptability of the concept by the pilot.
This experiment was described in the document [fr7].
The FAST ASAS prototype was implemented on a simplified cockpit simulator on which pilots could
experiment the concept. The other aircraft involved in the simulation was simulated by a traffic
generator. The FAST experiments involved 18 pilots from Europe and the US.
The evaluation focused on the following points:
• Flight crew task sharing and procedures in autonomous operations• On-board automation/tool support required
• Crew expectations of the ground component
• Feasibility of the separation task delegated to the cockpit side.
The main conclusions of this experiment were based on the response to pilots’ questionnaires, and are
the following:
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• The system was found to be very simple and very efficient to use.
• The interface (as detailed in the section 2.2.5) is well accepted but further enhancements arerequired with weather radar overlay to make definite conclusions about the colour aspects as well
as on the forbidden zones.
• The conflict resolution interface appears approximately simple and easy to use despite thecomplex system behind it.
• Both look ahead times (6 and 10 minutes) are found very comfortable providing pilots with
sufficient time for resolution.• There was no difficulty to use either the manual or the automatic resolution modes.
• The system induced workload stays well within acceptable bounds.
• In abnormal cases or when facing abnormal situations, pilot would have liked to obtain supportfrom ATC in their decision making process.
More details concerning the experiment results are provided in Annex C.
EACAC experiments
In the framework of the EACAC study, an initial evaluation, presented in the document [fr11] was set
up in 1999.
The main objective of this evaluation was to get “feedback” from the controllers and the pilots, and toassess the feasibility and potential interest of the concept. Both en-route and ETMA applications were
evaluated.
Due to the assumptions made − simple ATC environment, small number of participants − results were
only qualitative indications gathered through questionnaires and debriefing.
The main conclusions from both controller and pilot point of view are described below.
Controller point of view:• The concept was generally understood.
• The method is thought generally “compatible” with current working methods.
• The method is considered “absolutely” feasible from a human point of view.• The method is found globally useful and effective and could reduce controller workload, enabling
the controller to undertake others tasks.
• A certain gain in safety could be obtained.• The notion of “flexible use of delegation” would enable gradual growth in confidence and would
also provide flexibility to use the method under different traffic conditions, airspace constraints
and controller’s practice level.
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• The concept is seen as an additional tool, “promising” with a “great potential”.
• The conditions of applicability of the method must be respected, otherwise it could worsen the
situations, resulting in an increase of workload and communication.• A clear definition of the sharing of responsibility is needed.
• It appears that the training of both controller and pilot is an important issue to guarantee a safe and
efficient use of the method.
Pilot point of view:• The tasks are found interesting and a better flight management and trajectory optimisation could
be obtained.
• The methods also allows a better understanding of the air situation from the pilot point of view.• The workload in the cockpit would increase and may induce stress.
• The method is thought compatible with current working methods but may be not compatible under
abnormal situations.• The change of responsibility for separation assurance, although it is felt generally acceptable,
could make it harder to accept the method.
A new experiment, involving only controllers, was set up in June 2000. The objective of this second
larger scale experiment was to validate the concept in a more realistic environment, set up a ‘final’
version of procedures, especially on the phraseology and co-ordination mechanisms. It also aimed atgetting a first quantitative evaluation of the expected benefits in terms of workload reduction for the
controller and flight optimisation for the pilot.
The results of this experiment are not yet available.
2.7.1.4 Institutional Aspects
2.7.1.4.1 Procedures
FAST rules and procedures
FAST provides Extended Flight Rules (EFR) rules and procedures for autonomous aircraft operations.
The EFR procedures, as described in [fr2, fr4], consist in defining how a change in trajectory shall be
made.The procedures are the following:
• An intention of change in trajectory shall be broadcast at least 30 seconds prior to the manoeuvre.
• A new trajectory shall be conflict free within the useful radius of ADS-B, i.e. 120-150 Nm.
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• When an encounter occurs, the following procedure shall be engaged:
1. Encounter must be acknowledged at the latest at 7 minutes prior to the encounter (first point of
separation minima)2. The execution of the EFR rules will assign priorities to aircraft involved in the encounter. The
identified priority must be acknowledged at the latest 6 minutes to encounter
3. Once the priorities are identified, intention to change trajectory, i.e. new trajectory informationmust be broadcast at the latest at 4 minutes to the encounter
4. Effective manoeuvre can only be engaged 30 seconds after the broadcast of the new trajectory.
The EFR rules aim at assigning priority between aircraft directly involved in the conflict. The
documents [fr2, fr3, fr4, fr6] present the first version of the EFR. A second version which will take
into account the surrounding “buzzing” aircraft is in preparation.
• The EFR purpose is to assign priority to aircraft in encounters during autonomous aircraft
operations, i.e. to identify which aircraft should give way or manoeuvre to avoid a separationinfringement; how (i.e. by which procedure) and when a manoeuvre should be executed.
• The EFR proposed are an extension of the Visual Flight Rules (VFR) and the ATLAS Flight Rules(AFR) and take advantages of the surveillance data available in the flight deck. They cover
encounter involving more than two aircraft.
• The strategy of EFR for priority assignment considers:
1. The manoeuvrability of each aircraft involved in the encounter,
2. The availability of each aircraft in its current flight phase,3. The distance to the encounter of each aircraft.
The details of the strategy to assign priority is provided in Annex E.
EACAC operational procedures
EACAC provides operational procedures for limited delegation applications.
The main points of the procedure can be summarised as follows:1. The controller keeps the initiatives: the detection of the problem, the definition of the solution and
the decision of transfer of responsibility remain within his/her role and initiative.
2. The controller has the ability and responsibility to select the appropriate level of delegation whichshould depend on traffic conditions, airspace constraints and controller’s confidence in the
delegation.
3. The controller must respect the applicability conditions.
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4. The delegation requires the pilot’s agreement.
5. The delegation consists in three phases: identification phase, instruction phase and end of
delegation.
The details of the procedure overview as defined in [fr12] are provided in Annex E.
EACAC considers two classes of application and proposed three levels of delegation for each:
• Crossing and passing applications in en-route airspace. The levels correspond to reporting,
maintaining the separation and providing the separation• Sequencing operations – in-trail following and traffic merging – in the extended Terminal
Manoeuvring Area (ETMA). The levels correspond to reporting (except for in-trail), maintaining
the separation and resuming then maintaining the separation.
Detailed concerning these levels of delegation are provided in Annex E.
A phraseology has been defined for each application, examples of phraseology for the identification
phase, the lateral crossing and the station keeping applications are provided in Annex E.
2.7.1.4.2 Responsibility issues
As mentioned in [fr12], EACAC assumes that there are no changes of responsibility in the case oflimited delegations: “The delegation does not impose any change of responsibility between controllers
and pilots. The delegation can be considered as a new instruction. The controller is responsible for
providing an appropriate instruction that will ensure the separation and which is acceptable (flyable)by the pilot. The pilot is responsible for following this instruction.”
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2.8 Review of the JANE, NEAN and NEAP projects
Projects overview
The North European ADS Broadcast Network (NEAN) was designed to develop, evaluate and
demonstrate new technologies for data links and networking, and thereby contribute to theimplementation of a network for CNS in the provision of ATM in Europe.
The NEAN project started in January 1996 and ended in December 1998.
The development and evaluation of various applications was originally part of, and funded by the
NEAN project. This was later moved to a new project, named North European CNS/ATM
Applications Project (NEAP).
The NEAP Project started in September 1997 and ended in December 1998.
The NEAN project has been divided in three parts:
• Development of infrastructure:The objective was to develop an STDMA VDL Mode 4 / ADS-B cellular ground infrastructure
with adequate elements for supporting basic demonstrations and evaluations of the STDMA
technology and the ADS-B application in an ATM context on an international scale.Although the capabilities inherent in the system CNS, making a large number of applications
possible, the ADS-B functionality was focused on.
• Demonstration to the user community:
The objective was to demonstrate the benefits of an STDMA / ADS-B system to users, with the
North European CNS/ATM Applications Project (NEAP) as the most important demonstrator.
• Evaluation of the ADS-B surveillance functionality:
The objective was to validate the surveillance functionality of an STDMA / ADS-B based systemfor ATM usage by examining various technical performance parameters of the installed test-bed.
In addition to this, a cost database should be established by determining cost of
equipment/installations, operating costs and estimated costs for certification.
The objectives of NEAP were to investigate, specify, develop, test and evaluate civil aviation user
applications and services within an integrated communications (broadcast), navigation andsurveillance (CNS) concept based on the NEAN infrastructure. Activities focused on the following
domains:
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• Enhanced surveillance for Air Traffic Control (ATC)
• Pilot situation awareness
• Global Navigation Satellite System(GNSS) precision navigation capability for all phases of flight.
Through the definition and the evaluation of applications from these different domains, the aim of
NEAP was to:Ø Cover aspects of all phases of flight in a gate-to-gate concept, and therefore demonstrate the
suitability of a single integrated CNS system to support a range of operational services and
multiple phases of flightØ Demonstrate the capability and the suitability of that system to support individual applications and
services
Ø Address the potential benefits to be gained by their use in a future CNS/ATM concept.
In order to further develop the concept based on the VDL mode 4 technology, a NEAN update
programme (NUP) has been launched. NUP aims at certifiable applications that can be put intooperation by the end of the project. NUP is outside the scope of this revue.
One objective of the Joint Air Navigation Experiments (JANE) was the investigation of developmentsconcerning autonomous aircraft. In that context it was decided by DFS and Deutsche Lufthansa AG to
set up the JANEX I experiment in order to conduct flight trials together with the FREER3 project to
demonstrate the feasibility of autonomous aircraft operation in European airspace using existingprototype technology. The objective of the JANEX I project was the organisation and technical
realisation of all activities for the experiments in co-operation with FREER3.
One of the objectives of the JANEX I project was the demonstration of these flight trials at the IATA
conference “Global NAVCOM” in Berlin in October 1998.
Document overview
Most of the documents of the NEAN project are technical reports concerning the different phases ofthe network installation and the trials realised to validate the ADS-B surveillance functionality.
The relevant document regarding the CARE-ASAS review is the “Final project summary and
conclusion report”[ne5] which provides a definition of the CDTI used in the NEAP applications.
The main documents of the NEAP project present the applications selected and the methodology
tested used to validate them.For each application evaluated by the NEAP project three documents, the service description, the test
plan and the evaluation report, are provided. The documents related to the In-flight situation awareness
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application [ne11, ne12, ne13] will be reviewed since it is the only ASAS application treated by
NEAP.
For the JANE project, the document available is the JANEX I final report document [ne15].
The list of the NEAN, NEAP and JANE documents is provided in Annex A.
Detailed review of the JANE, NEAN and NEAP projects
Since NEAN is much more oriented towards the development of an air and ground infrastructure, and
the evaluation of the ADS-B surveillance functionality, it does not address explicitly the CARE-ASAS
Activity One review.
Nevertheless, as part of the first phase of the NEAN project which consisted in developing the ground
and air infrastructures, some specific developments were performed in order tosupport the dedicated demonstrations and evaluations. In particular, a Cockpit Display of Traffic
Information (CDTI) was implemented and installed on several aircraft.
Regarding the ASAS concept, only this CDTI is relevant and will be detailed.
NEAP selected the following applications in its test programme:
• GNSS precision navigation capability for en-route and approach• On ground situation awareness and taxi guidance
• In-flight situation awareness
• Enhanced ATC surveillance – downlink of aircraft parameters• Automatic Terminal Information Service broadcast; ATIS.
• Extended helicopter surveillance.
• Prevention of runway incursion.
Hence, at least one application, or service, of each component of the CNS/ATM concept was included
in NEAP. Combined, they demonstrated a single system solution for seamless gate-to-gate operations.
NEAP put emphasis on gaining real-world experience. The testing and the evaluation of each
application relied on live trials which took place on revenue flights.
Within the CARE-ASAS Activity One, the In-flight situation awareness application evaluation will be
reviewed in detail since it is the only ASAS application, considered as the first stage to more complexASAS services.
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Therefore, through the study and the trials to evaluate the In-flight situation awareness, the NEAN and
NEAP projects covers the following points of the CARE-ASAS Activity One review:
• Decision Support Tools: A CDTI has been provided by the NEAN project to support the In-flight
situation awareness application.
• Capacity, efficiency and safety issues as well as transition and human factors issues have been
addressed through the trials.
• Certification issues have been assessed through the NEAP certification study which in particular
addressed the Station-keeping using Airborne Situation Awareness – CDTI.
As mentioned previously, the objective of the JANEX I project was the organisation and technical
realisation of all activities for the experiments in co-operation with FREER3. This included the co-
ordination of the German flight trials and the ground support.The JANEX I document reported the scenario and the technical set up and explained the different
flight trials.
No specific results concerning ASAS application were provided by the JANEX I project. The resultsof the JANEX I trials are those of FREER3 presented in Section 2.7.
2.8.1.1 Technological Issues
2.8.1.1.1 Decision Support Tool
A CDTI has been developed in the NEAN project. This CDTI provided information of airborne traffic
equipped with a STDMA/VDL Mode 4 ADS-B transponder, and traffic information through the traffic
information service broadcast (TIS-B) for the non STDMA equipped traffic.
The aircraft information, presented on a dedicated display in the cockpit named the MMI5000,
contained:• Aircraft position
• Aircraft identification tag (usually flight number)
• Relative altitude• Prediction vector.
The MMI5000 functions were extended in steps with input from different projects supported by theNEAN project.
The trials are briefly described since they are the basis of the application evaluation.
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To evaluate the in-flight situation awareness application, several tests were performed, all of them
taking place on revenue flights. Therefore, at all time the tests were based on real life situations whereno specific scenario was possible. Evaluations focused on the operations in the Frankfurt area, as most
of the flight were inbound or outbound Frankfurt airport and as the TIS-B capability was available in
the Frankfurt terminal area.
For the trials the MMI 5000 cockpit display was used in Boeing 747-200s.
The evaluation was performed through the use of questionnaires, which were distributed to the
aircrew. A clear distinction was made between the existing trial equipment and an assumed certified
system, thus some results are based on assumptions in order to assess possible long-term benefits.
The trials had the following application-specific objectives:
• Evaluate the concept of in-flight situation awareness, and in particular, address the expectedbenefits:
– Improve safety, capacity and efficiency
– Significantly improve pilot’s situation awareness– Allow station keeping capability
• Demonstrate in-flight situation awareness as a component of a gate-to-gate concept.
• Evaluate the suitability of STDMA/VDL Mode 4 as the basis for in-flight situation awareness.• Develop and evaluate a common cockpit platform for supporting implementation and evaluation
of future in-flight situation awareness.
2.8.1.2 ATM Performance Issues
2.8.1.2.1 Capacity, Safety and EfficiencyThe following conclusions concerning ATM performance issues can be mentioned:
Capacity• Weather independent constant throughput and increased capacity is possible through adaptation of
VMC procedures to IMC (e.g. follow visually, climb through level of selected aircraft).
• Airborne station keeping with increased capacity is possible provided that separationresponsibility is clearly defined and operational procedures are in place.
Safety• ADS-B based in-flight situation awareness forms the basis for an additional safety net with pre-
warning times much longer than for TCAS, and therefore allows for early tactical flight path co-
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ordination rather than last minute conflict avoidance, resulting in an increased safety margin and
redundancy or TCAS.
Efficiency
• In-flight situation awareness including the display of the flight number of other aircraft allows
aircrews to optimise their flight profile according to the traffic situation (e.g. change of flightlevels between company aircraft).
• Potential to apply reduced separation minima due to enhanced surveillance accuracy.
More details concerning capacity, safety and efficiency are provided in Annex F.
2.8.1.2.2 Transition issues
TIS-B (uplink of radar data) enables in-flight situation awareness in high traffic density airspace with
few ADS-B equipped aircraft, and thus is a key factor in a transition phase.
2.8.1.3 Human-factors
The following conclusions concerning human factors issues have been are mentioned:
• In-flight situation awareness closes the information loop between ATC and the aircraft allowingdelegation of responsibilities to the cockpit. As a result, ADS-B based free flight scenarios in low
density airspace are possible in the long term.
More details about the aircrew impressions are provided in Annex F.
2.8.1.4 Institutional Aspect
2.8.1.4.1 Certification issues
The certification ‘road map’ produced by the NEAP project underlines the following points
concerning the Station-keeping certification.
• The station-keeping using CDTI should be acceptable, subject to concerns regarding pilot
workload and the respective responsibilities of the pilot and ATC.
• Regulatory authorities are likely to be reluctant because of liabilities issues.• A key question is the interface to the FMS and its role in monitoring separations.
• Airlines, manufacturers and regulatory authorities must carry out these two calculations:
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1. They must ensure that the potential of increase in risk from reduced separations is, at least, offset
by the calculated improvements in the position of both aircraft and in the assurance and
monitoring of their relative separation2. The increased liability from the transfer of separation function to the cockpit is met by the
commercial benefits of increased capacity and efficiency.
From this analysis, the following recommendations are made:
• Urgent development of European Standards - to support VDL Mode 4 and its exploitation. These
European Standards should include:- Radio Performance characteristics, to support radio Type Approval
- Data-link Performance Characteristics
- Cockpit Display of Traffic Information (CDTI)- Communication services and applications
- Network standards and Performance Requirements.
• Incorporation of European Standards for VDL Mode 4 into JAA Joint Technical Standards Orders(JTSOs) for certification and aircraft installation purposes.
• Development of JAA Operational Standards for ADS-B airborne applications.
• Development of a Certification Strategy for VDL mode 4 to be incorporated as part of a GeneralImplementation Strategy.
• The Certification Strategy should take account of cost/benefit issues.
2.9 Review of FARAWAY project
Project overview
The Fusion of Radar & ADS data through two WAY data link (FARAWAY) project investigated
the enhancements in terms of operational performance of ground surveillance systems and in aircraft
navigation which are possible through the use of ADS-B/TWDL (Two Way Data Link) based onSTDMA technique and through appropriate fusion of ground generated surveillance data (radar data)
with aircraft position and status data transferred to ground by air-ground data-link (ADS data).
The project started in January 1996 and finished its first phase in July 1998. An extension of the
program has been performed under the name FARAWAY II.
Within the scope of the project, a pre-operational demonstrator, including ground and airborne
components, has been developed to be used for evaluation purposes (trials) to support new operational
procedures and services based on the fusion of radar and ADS-Broadcast data through TWDL. Thedemonstrator, which provided a complete data communication system between ground and air, was set
up at the Ciampino ACC and TMA/APP and onboard three MD 80s of Alitalia. It used prototype VDL
Mode 4 data link equipment to provide an ADS-B service.
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The FARAWAY project has investigated five applications of the data link:
• ADS-Broadcast using VDL/STDMA data-link• Enhanced aircraft navigation based on GPS integrity and augmentation
• Data fusion of surveillance information provided by radar tracking and ADS-B
• Traffic Information Service Broadcast (TIS-B) using VDL/STDMA data-link• Airborne Situational Awareness on CDTI.
The validation of the selected applications was directed to:• assess the technical performances, verifying that the system works correctly from a functional
point of view and measuring its performances. To do this, a set of correlated indicators
commonly accepted to describe the performances of the application was established for eachapplication.
• assess the user acceptance, estimating user’s attitude to the applications which exploit these new
technologies utilised in the system. The user acceptance assessment was assessed throughquestionnaires, interviews and by focus groups, which aimed at synthesising the results and
envisioning possible design solutions.
As part of the validation process, flight trials were conducted with all equipment deployed at the test
site and avionics integrated in the aircraft. During these trials, all the relevant data were gathered from
systems considered as “reference” and from the system developed within the project, both operating inthe “real life environment”.
The FARAWAY demonstrator has been enhanced in the FARAWAY II project to extend the VDLcoverage to the Alps and to the Southeast Mediterranean and to add new capabilities such as
controller-pilot data link communications (CPDLC). Other objectives were also to connect
FARAWAY with NEAN, achieving a continuum of ADS-B coverage from Scandinavia into theMediterranean, integrate FARAWAY into the AVENUE project and deal with certification and
standardisation issues.
Document overview
The FARAWAY project followed a standard approach to system development and in this contextproduced the “User requirements”, the “System and equipment draft specifications” and a “Validation
plan”. Nevertheless, these documents were not available.
The main FARAWAY documents which have been reviewed were the “Final report document” andthe specification of the CDTI used for the experiments [fa1, fa2].
The lists of the FARAWAY documents are provided in Annex A.
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Detailed review of the FARAWAY project
As part of the CARE-ASAS Activity One review, the Airborne Situational Awareness application will
be reviewed as this application is considered as the first ASAS application before more complex
ASAS applications.
The details of the five applications (mentioned in the Section 2.9.1) proposed by FARAWAY is
provided in Annex G.
Through the evaluation of the airborne situational awareness application, the FARAWAY project
covered the following points of the CARE-ASAS Activity One review:
Decision Support Tool: A CDTI was developed and installed on three aircraft.
Transition issues have been addressed through the conclusion of the TIS-B study.
Human factors: Live trials involving pilots and controllers were performed for the user acceptanceassessment.
Certification and standardisation issues should be covered by the FARAWAY II project.
2.9.1.1 Technological Issues
2.9.1.1.1 Decision Support Tools
For the evaluation of the airborne situational awareness, the Control Display and Navigation Unit(CDNU) was developed and installed on three aircraft.
The traffic display function of the CDNU provide the pilot with CDTI capability.
The CDTI provided by the CDNU traffic display proposed the following functions:
• The traffic display depicts the surrounding traffic situation on an horizontal plan view.• According to the selected mode of operation, other traffic may be represented by different
symbols.
• Traffic symbols are displayed at the relative horizontal position (distance, bearing) from the ownaircraft symbol.
• Further attributes like the callsign, the aircraft altitude and an indication if the aircraft is in climb
or descent can be given.
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FARAWAY provided a CDTI specification including:
• The User requirements, which detailed:– The symbology used to display information
– The different traffic display selections
• The Software requirements, with:– A general description of external interfaces, functional breakdown, data flows and data
stores
– A description of the process logic– A description of internal data.
The details concerning the CDTI specifications are provided in Annex G.
2.9.1.2 ATM Performance Issues
2.9.1.2.1 Transition issues
One of the objectives of the FARAWAY project was to evaluate the TIS-B application.
TIS-B is considered as a very important application for the operation of mixed mode ADS-B/SSRenvironments, since it delivers the benefits of airborne situation awareness without equipping all users
with ADS-B equipment. It is also very important for transition.
The evaluation of the TIS-B application focused on the accuracy of the aircraft position reports
received on-board by the CDNU.
The results obtained suggested the possibility to exploit the TIS/B application in support of the pilotsituational awareness since the overall traffic picture was practically consistent with the one presented
to the controller.
2.9.1.3 Human factors
The objective of the user acceptance evaluation was to assess if expected benefits, e.g. reducedworkload, reduced communication, improved quality of information, HMI friendliness, were achieved.
Because of demonstrator constraints (on board and ground systems in shadow mode), some of theusers and impact assessments were not really verified during the trials but were deduced from user’s
“feeling” and “perception” about how the applications could work if used in an operational
environment.
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The analysis of the pilots’ activity both in the standard conditions and in the test flights showed that
the CDTI system using ADS data can increase the pilots awareness about the surrounding traffic.
Information to be provided to the pilots
• Not all the ADS information is equally relevant and not all the information has to be displayed.• One of the pilots’ requirements about the use of this information is that it has to be quickly
accessible and interpretable, in order to minimise the demand of cognitive resources (attentional
and perceptual resources).• The part of the relevant traffic to be displayed depends on the different phases of the flight:
– take-off and approach phases: the traffic within the 10 miles (horizontal) and the 1000
feet (vertical) from the a/c.– en route: the traffic within the 50 miles (about 7 minutes of flight) and the 2000 feet
from the a/c.
• The information to provide for each a/c displayed are the a/c identifier code (the transpondercode), the representation of the speed (e.g., an arrow) indicating the a/c’s behaviour
(climbing/descending).
Impact on the co-ordination and the communication among controllers and pilots
As part of the airborne situation awareness application, the following issues have been underlined:
• Pilots anticipation of the traffic evolution.
As mentioned above, the ADS data can enhance the pilots’ awareness of the surrounding traffic; in
particular, the information provided should allow the pilots to have a better anticipation of thetraffic’s evolution.
There are two most important consequences of that:
– the decrease of the pilots’ requests for shorter route in condition of high traffic withinthe sector because he can see that the request can not be granted
– the aircraft “self spacing”, that is the pilots can use the information for maintaining the
safety distance between the a/c without the controller’s intervention.
• Decrease of VHF communications.
The airborne situation awareness application can help in decreasing the frequency load for twomain reasons:
− a limited number of requests for information from both pilots and controllers
− a limited controllers’ intervention on the traffic due to the pilots’ awareness of thesituation which allows to maintain autonomously the safety distance.
2.9.1.4 Institutional Aspects
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2.9.1.4.1 Certification and standardisation issues
Certification and standardisation issues should be covered by the FARAWAY II project.
Indeed, the main theme proposed in the FARAWAY II project is that of transporting ATM services
onto the VDL Mode 4 infrastructure and to proceed with enhancement of scope so as to:• secure interoperability of FARAWAY and NEAN systems and Flight Management Services
through the constitution of a pre-operational scenario adopting compatible technologies, providing
inputs to on-going standardisation within ICAO, ETSI and EUROCAE and certification initiatives• develop a set of advanced validation tools to assist certification.
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2.10 Review of the SUPRA project
Project overview
The objective of the Support for the Use of PResently unserved Airspace (SUPRA) project was to
apply the ICAO/FANS (International Civil Aviation Organisation / Future Airspace NavigationSystem) CNS/ATM concept (Communications, Navigation and Surveillance / Air Traffic
Management) to air traffic in the General Aviation sector.
The project investigated cost-effective ATM solutions to ensure high safety levels in currentlyunserved airspace, i.e. European private or regional airports within non controlled airspace where ATC
services are not provided (airspace G and F), thereby supporting the growth of the number of flights
to/from regional airports.
The project was started in March 1996 and ended in May 1997.
The project consisted of a feasibility study and a demonstration phase to give a limited validation of
the new CNS/ATM system features, and aimed to show the benefits of developing and installing
affordable systems which can provide unserved airspace with high levels of safety andsurveillance/control. The objective was also to demonstrate that those systems using existing
technologies could provide required functions and capabilities to all users at low cost.
This project focused small airports and General Aviation users.
The first step of the project was to consider the different requirements suggested by airborne and
ground users. The second step was to define the SUPRA system that addressed two main issues:general system requirements for a small and modular ATM system serving general aviation and
regional airport service providers, and a system requirement specification for the SUPRA
Demonstrator itself.
The user requirements were stated from the following important issues stressed by the airport and
general aviation users:• the lack of complete communication coverage and radar services coverage
• the difficulties in knowing the neighbouring traffic around the aircraft, as no air traffic control was
provided for these flights• the difficulty in obtaining updated and continuous meteorological and aeronautical information
• the difficulties of the General Aviation to accede important airports
• the cost-effectiveness.
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In order to cope with the various requirements of the heterogeneous user groups, SUPRA proposed
requirements for an open and modular system design which should be scaleable in functionality and in
size to the various application needs.
In addition, SUPRA designed its demonstrator which was a system based on available low-cost
products, tailored in such a way that the overall system accomplished a set of user requirementsaddressed by the project, mainly unserved airspace users. In addition to this, needs of the service
providers in the served airspace were taken into account in order to demonstrate that the system was
also technically feasible for alleviating congestion of served areas. So, SUPRA Demonstrator Systemcould support two operational environments (served and unserved).
The SUPRA demonstrator comprised an airborne segment, a ground segment and a data-link segment.Three mobiles were equipped with transponder, two aircraft’s and one car. The air/ground integration
was realised by STDMA VHF data-link.
In order to validate the SUPRA concept, trials were performed based on the demonstrator.
The SUPRA Validation covered three main areas:1. Technical working of the SUPRA demonstrator different functionality for the ground station, the
on-board equipment and the transmissions
2. Adequacy to the user requirements, i.e. controllers, pilots and conditions on Communications3. Respect for the principal GA constraints (low costs, technological impacts, easiness of installation
and operation, interoperability with ATM, ...).
Document overview
The documents provided by SUPRA are related to the different steps of the project: the userrequirements establishment, the specifications of the generic ATM system providing all necessary
CNS functions for SUPRA addressed users, the description of the SUPRA demonstrator and the
presentation of the trials’ results.Regarding the CARE-ASAS Activity One review, the relevant documents which were reviewed were
those concerning the results of the trials [su4, su5].
The list of the documents is provided in Annex A.
Detailed review of the SUPRA project
SUPRA defined a demonstrator with an air segment, a ground segment and a data-link segment.
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The airborne segment of the demonstrator supported the following functions:
• Navigation Data Processing and Display which allows the pilot to know precisely where they
are• Airborne situation awareness which allows the pilot to see surrounding traffic if it is equipped
with ADS-B
• Display of ATIS (Automatic Terminal Information Service) information which allows the pilotto see ATIS report.
Therefore, within the SUPRA project, the airborne situation awareness application was provided to thepilot. As it is considered as the first application which leads to more complex ASAS applications, the
points related to this application were reviewed in detailed.
So, as part of the CARE-ASAS Activity One review, the following items were covered:
Decision Support Tool: SUPRA proposed the Navigation Data Processing and Display (NDPD), anairborne cockpit display which provided navigation situation awareness to the pilot.
Human factors: Flight trials were performed to validate the SUPRA system.
2.10.1.1 Technological issues
2.10.1.1.1 Decision Support Tool
The Navigation Data Processing and Display (NDPD) is an airborne cockpit display which providednavigation situation awareness to the pilot, and displays:
• The position of the own aircraft against a "moving map" background. The map can also showrunways, taxiways and surface vehicles when the aircraft is on the airport surface.
• The positions of aircraft in the vicinity using ADS-B information received from these aircraft or
through the uplink of correlated surveillance data from the ground.• For each aircraft the following information: aircraft ID, position, altitude and true track (i.e.
ground velocity vector). True track is displayed using a prediction line that shows the predicted
position of the aircraft (assuming it stays on a straight course) in a few minutes in the future. Thetime of the prediction can be changed and, for ADS-B, the true track is based on actual GPS
velocity (not from extrapolating old position reports).
Filters could be applied to the display, so that only aircraft within a certain altitude from the aircraftitself were displayed
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2.10.1.2 Human factors
The validation aimed at verifying the adequacy to the user requirements , and the respect by thesystem of the principal GA constraints.
Pilots and controllers involved in the validation expressed their good impression of the possibilitiesoffered by the STDMA, specially in the field of safety and traffic regulation in the increasing air
traffic load. Accuracy and new features were also very well appreciated by controllers and pilots.
The following results concerning the measurement of the three parameters used to validate the
concept, as described in [su4], were obtained:
Technical parameters
1. Suitability, completeness and continuity of the air traffic situation presentation
2. Suitability, availability and accuracy of the aircraft own position displayed on the cockpit3. Suitability of the situation awareness presentation of the surrounding traffic.
Operational parameters1. Usefulness and relevance of:
• moving map display2. Relevance of the mobile own location display
3. Interest to exchange data and usefulness to automatically refresh information.
Impact parameters
1. Ease of use of the equipment on-board
2. Ability to interchange data within ATM, capacity to insert general aircraft into served airspaceand capacity to accept commercial aircraft into unserved airspace. Total compatibility with ATM
concept
3. NDPD allows to fly in better safety conditions, being feasible in the GA context.
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2.11 Review of the NLR/NASA Free Flight work
Project overview
The Dutch National Aerospace Laboratory (NLR), has been investigating the feasibility of airborne
separation concepts, in co-operation with NASA, FAA and the RLD for several years, within theAdvanced Air Transport Technologies (AATT) project. The scope of this work was to investigate the
limits of airborne separation. During this study many issues have been investigated and reported. A
summary of some of these issues will be provided in this chapter, based on the relevant documentationdistributed by NLR within the scope of the CARE-ASAS activity one.
Document overview
Most of the information presented herein have been extracted from the NLR Free Flight Project
document (1999), that represents a detailed report of the NLR activities on Free Flight carried outduring last decade. A list containing all papers and presentations of this study is available on the NLR
web site: www.nlr.nl :
1. Overview of NLR Free Flight Project 1997-1999, Contract Report May 9, 2000
2. Self separation from the air and ground perspective, NASA/NLR
3. Air traffic controller strategies in resolving free flight traffic conflicts: the effect of enhancedcontroller displays for situation awareness, NLR 1997
4. Free flight with airborne separation assurance, NLR
5. Man in the loop part of a study looking at free flight concept, NLR
Detailed review of the NLR work
The NLR study about Free Flight concept covered most of the issues discussed by the CARE ASAS
activity 1:
• Technology issues, through the assumptions made regarding the availability and specificationsof the ADS-B data, the (non) use of intent information and the assumed RNP, and through the
decision support tools (conflict detection and resolution) and a CDTI display;
• ATM performance, related to the feasibility of the ASAS without ground based controller andsolutions for the air traffic management;
• Human factors , dealing with pilot workload and acceptability of new concepts and systems;
• Institutional aspects , in a minimal way, by assuming full responsibility for the aircrew, withonly Traffic Flow Management and a form of traffic arbitration system to ensure sufficient
airspace/runway and enforcement of the CD&R rules.
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In the documents reviewed, major relevance has been given to the airborne perspective, focusing on
the traffic display integrated in the navigation display.
2.11.1.1 Technological Issues
2.11.1.1.1 CNS requirements
The study is based on the following assumptions:
• no ATC task in Free Flight Air Space (FFAS)• all aircraft fully equipped in FFAS
• CDTI
• ADS-B update rate of 1 Hz• RNP of 1 nm
• direct routing (horizontally and vertically)
• upper airspace only• separation minima equal to today
• look-ahead time (5 min.) as alert zone
• conflict resolution advisories by system
2.11.1.1.2 Decision Support Tools
Cockpit Display of Traffic Information (CDTI)
The Cockpit Display of Traffic Information (CDTI) is one of the tools that form the AirborneSeparation Assurance System (ASAS). This tool is in charge of giving pilot the situational awareness
of surrounding air traffic. The NLR CDTI display is used both for traffic information and navigation
information.
The NLR CDTI display is able to show both the horizontal and the vertical navigation situation.
Declutter functions have been added, both in vertical and horizontal modes.Different colours were used to show the surrounding aircraft position and equipment: In the first phase
trials the aircraft decreasing distance (negative range rate) were blue coloured, while those increasing
distance (positive range rate) were coloured in red . In the second phase trials the colour was differentbetween ASAS equipped (white) and not ASAS equipped aircraft (blue).
Conflict detection
The conflict detection process consists of the following steps:
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• to predict the ownership’s trajectory for the look ahead time horizon
• to select potential intruders for the look ahead time horizon
• to predict the intruder’s trajectory• to estimate the minimum distance at the closest point of approach (CPA)
• to compare the minimum distance with the required separation
In the NLR study all these steps have been performed by the conflict detection module of ASAS.
In order to detect a conflict the ASAS used the state (position and velocity) based detection with ageometrical resolution method.
The computation is based on a look ahead time of 5 minutes. The intrusion alert is shown to the crewwith two different levels: a standard conflict alert when the intruder conflict time is between 5 and 3
minutes, while urgent conflict alert when the conflict is expected within 3 minutes.
The conflict alert consists of a sound (aural alert) and warning light flashing with different frequency.
The symbology used during the detection of the conflict is linked to the geometry of the conflict, asthe resolution algorithm used depends on conflict geometry.
Conflict resolution
Analysing various algorithms for conflict resolution the one chosen in the NLR study was the
“modified voltage potential algorithm”. Basic voltage potential algorithm foresees all aircraft asassociated to positive charged particles and destination to negative charged particles. A modification
of this algorithm can be used to calculate the avoidance vector related to two aircraft in conflict. This
vector is the one connecting the point of minimum distance of ownership aircraft and the edge ofintruder protected zone. This vector can be decomposed into a speed change and a heading change
vector in the horizontal plane. The same procedure can be applied to calculate the change in the
vertical plane, thus calculating a resolution manoeuvre to be executed.
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Intruder’sprotected
zone
Headingchange
Speedchange
Avoidancevector
Minimumdistance
Ownship
Intruder
Figure 2 NLR’s resolution geometry
In the case of multiple conflicts it is possible to sum all avoidance vectors to solve the conflicts.
Even if the conflict can be solved by only one of the two aircraft, normally both them will manoeuvreat the same time, so this method is based on a co-operative manoeuvre, giving the following
advantages during the conflict resolution phase:
• effective (it solves conflicts)• efficient (in terms of fuel and time)
• fair (distributes efforts and costs among aircraft in equal mode)
The symbology on the display will show aircraft moving away white coloured, while cyan aircraftgetting closer. The level of alert is red or amber in the case of the conflict is respectively between 5
and 3 minutes or less than 3 minutes.
The execution of the resolution can be performed manually, automatically or in a combined way.
Predictive ASAS (PASAS)
Based on the results of the first experiment, ASAS should provide more protection for suddenmanoeuvres of aircraft nearby, causing intrusions of the protected zone. This resulted in the
development of Predictive ASAS, or PASAS. PASAS calculates which tracks, speeds and vertical
speeds will result in a conflict with another aircraft within 5 minutes. The results of these calculationsare shown as "bands" on the Primary Flight Display and Navigation Display. In fact, PASAS generates
"no-go" bands on the speed tape, the vertical speed tape and the heading/track tape. A distinction is
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made between potential conflicts within 0 to 3 minutes away from intrusion, displayed red, and
potential conflicts between 3 and 5 minutes away from intrusion, displayed in amber. An extra rule for
all pilots was introduced: pilots were not allowed to turn, climb or descend into an amber or red band.The net result is that intrusions due to sudden aircraft manoeuvres nearby, like an aircraft reaching a
top-of-descent, are prevented.
The Primary Flight Display (PFD) is shown in figure 3. The added elements to the standard Fokker100 PFD symbology are the PASAS "no-go" zones on vertical speed, speed and heading/track tape.
Figure 3: Primary Flight Display with PASAS bands.
A Navigation Display is shown in figure 4, with clear "no-go zones" on the heading/track tape.
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Figure 4: Navigation display with PASAS "no-go zones".
The "no-go" zones can be used pro-actively by the pilots to prevent conflicts.
Additional information on the navigation display is the distinction of aircraft equipped and aircraft not
equipped with ASAS equipment. Equipped aircraft are shown in blue, whereas unequipped aircraft arewhite.
2.11.1.2 ATM Performance Issues
2.11.1.2.1 Capacity, efficiency and safety issues
The study has investigated capacity and safety issues through the Human Factors aspects, whereby the
scenarios of the man in the loop experiments were varied such that traffic densities of up to 9 times the
normal European traffic densities were probed. Also a number of non-nominal events were included toprobe the effect on perceived safety by the aircrew. The human factors and performance data showed
no unacceptable situations even with the relative high densities and/or non-nominal events.
Fuel efficiency has also been studied by means of model-based fast-time simulations. Significant fuelsaving have been calculated due to the direct-to nature of the fully autonomous scenarios and because
of the continuous cruise-climb capability.
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2.11.1.2.2 Transition aspects
The NLR has also performed a study of mixed equipage scenarios. Three ATM operational concepts,
or scenarios have been defined, implemented and tested during the 1998 experiment. The assumption
was made that equipping aircraft should be immediately beneficial to the airlines and equipping shouldbe economy driven instead of mandatory. Therefore, all ATM concepts have been designed to benefit
the equipped aircraft, without excluding the unequipped aircraft.
The means to electronically "see" the unequipped aircraft is Traffic Information Service – Broadcast(TIS-B) rather than ADS-B. TIS-B assumes a ground station will uplink radar data of the unequipped
aircraft in the same format as ADS-B does.
Division by Flight LevelIn this condition, the airspace above a certain altitude (the “Lower Free Flight level”) is reserved for
equipped aircraft only. A transition layer just above the Lower Free Flight level is used as a buffer
zone for aircraft transitioning to and from Free Flight, see figure 5.
Figure 5: Flight Level ATM condition.This buffer zone is employed to avoid predicted conflicts and possible intrusions of protected zones
between free flying and controlled aircraft if only a single Free Flight Level would be used. Flying
high has a clear economic advantage for cruising aircraft. Another advantage of this method is that itallows a gradual transition to free flight by lowering the altitude limit, similar to the National Route
Program in the US.
Division by Protected AirwaysIn this concept, the airspace structure remains largely intact. Airways are still present for controlled,
unequipped aircraft. The ASAS equipped aircraft, however, have the right to leave the airways for
direct shortcuts to their destinations, whereas the controlled aircraft have to stay within the airways.
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Free Flying aircraft have the right to cross an airway but only if they ensure a conflict-free pass. The
advantage of ASAS equipage is direct routing, depending however on the efficiency of the
conventional airway structure. This operational concept is illustrated in figure 6.
Figure 6: Protected Airways ATM condition.
Fully Mixed ConditionIn this case, all aircraft are able to fly direct routing. The controlled aircraft are monitored by the
ground (ATC) using the same conflict detection module as is used in the airborne ASAS. ATC
performs the conflict resolution task for the unequipped aircraft. By using a substantially longer look-ahead time for the conflict probing for the unequipped aircraft, these aircraft will always avoid ASAS
equipped aircraft without a need for the equipped aircraft to manoeuvre. This is clearly beneficial for
the equipped aircraft. If all works as intended, the equipped aircraft will never detect a conflict with anunequipped aircraft because this will be resolved before it will be in the look-ahead time of the ASAS
equipped aircraft.
Experimental Design and scenariosA 2x2x3 within-subjects design varied the following three factors:
• Traffic Density - low density versus high density (5 respectively 15 aircraft under sector control)
• Equipage - 25% versus 75% ASAS equipped• ATM operational concept (or ATC condition) – Flight Level, Protected Airways and Full Mix.
A total of twelve test sessions were run per subject pilot, lasting twenty to thirty minutes each.Including briefing, familiarisation, training, experimental runs, breaks, and debriefing, the entire
protocol required two full working days per subject. The pilots were asked to fly an ASAS equipped
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aircraft on a pre-programmed Flight Management System (FMS) route and to be responsible for the
separation with other aircraft.
The most remarkable result of this experiment was the fact that aircrew could handle denser traffic
scenarios than controllers. Depending on the level of equipage either the flight-level (low equipage) or
the fully-mixed concept (high equipage) was preferred.
2.11.1.3 Human factors
The Human-in-the-loop simulator experiments have been analysed in order to investigate about human
factors aspects. The results have been carried out in terms of workload, acceptability and physiological
measurements (eye tracking).
- Workload
The workload has been rated on the basis of the Rating Scale of Mental Effort (RSME)
throughout the questionnaire answers.The results show that higher traffic density increases the workload of the pilot, while higher level
of equipage decreases workload. The protected airways ATC procedures (concept that makes able
only unequipped controlled aircraft to fly in a protected airway) is very sensitive to equipagelevel, so the transition issue in time is addressed with the protected airways ATC procedure.
The flight level procedure has resulted in the highest workload, and the fully mixed procedure the
most favoured candidate for ATM system with free flight capabilities.
- Acceptability
From the acceptability point of view, the ATM procedure has a clear effect on the acceptabilitylevels.
This indicates (and confirms the workload results) that the fully mixed ATM procedure is most
acceptable and the flight level ATM procedure the least one.The traffic density and equipage have a little effect on acceptability.
- Eye trackingThis analysis was conducted by means of eye-point-of-gaze data.
The percentage of the total fixation duration was classified separately for pilot flying and pilot
not-flying.Both the pilot flying and pilot not-flying spent 47 percent of the time watching the navigation
display with the traffic. The duration of fixation was a little bit higher for the pilot flying.
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2.11.1.4 Institutional Aspects
2.11.1.4.1 Operational procedures and responsibilities
The concept is based on full separation responsibility delegated to the aircrew, while traffic flow
management ensuring enough airspace and/or runway capacity. Furthermore the concept also takesinto account some form of traffic arbitration system which penalises aircrew who do not follow the
“rules of the road”. Pilot experiments showed that aircrew were sometimes inclined to “cut corners”
for time or fuel saving reasons. Other operational procedures have been discussed in the sectiondiscussing the transition aspects.
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3 Recently started projects
This chapter will describe on-going projects related to the ASAS. Four main European projects havebeen identified, which are described in a general format instead of the format used in chapter two,
since results are not known yet.
3.1 Mediterranean Free Flight (MFF)
The geographic location of the Mediterranean Area between the European Core Area and the States ofNorth Africa and Near East is a critical factor regarding future air navigation service provision in
Mediterranean Coastal States. The Core Area already shows high-density level of air traffic and the
latter has low/very low density and poor technological infrastructures.However, this boundary situation along with Mediterranean peculiarity of low air traffic complexity
scenario is an attractive draw to address studies and validation trials concerning the latest CNS
technologies and most recent operational concepts identified in the ECAC “ATM 2000+ Strategy” toaccomplish EATMS.
The Mediterranean Free Flight programme will avoid duplications by using as input the available
results of efforts from other European programmes/projects relevant for free flight operational concept(e.g.: FREER, FARAWAY, MA-AFAS, ADS-MEDUP, NUP, etc.).
MFF will also use the results of other relevant programmes/projects when they will be available.
Moreover, in the framework of CARE (Co-operative Actions of R&D in Eurocontrol) programme,ENAV has already started a co-operation with Eurocontrol to establish a sharing of efforts in the
ASAS Action (Airborne Separation Assurance System). While the Mediterranean Free Flight
programme would be devoted to explore the aspects of airborne separation assurance concept andapplications in En route airspace and in Low Density Area, the CARE ASAS Action would be devoted
to Core Area and Terminal Area.
MFF main objectives are:ð To provide technical and operational evaluation of integration, interoperability and safe use of
CNS/ATM technologies and applications suitable for future Mediterranean ATM scenario (e.g.
operational requirements and procedures based on the use of new CNS/ATM technologiesenabling the introduction of free flight operations in Mediterranean area);
ð To verify appropriate new operative procedures for ATM staff and crew in free routing and free
flight scenarios (e.g. the delegation of separation responsibility from ATC to aircraft and viceversa, through simulations and flight trials using specially equipped aircraft and controller
working positions);
ð To take advantage of the inherent results to address standardisation and further maturation ofrelevant CNS/ATM technologies and applications both in ground systems and avionics;
ð To define guidelines to implement free flight operations in suitable parts of the airspace.
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Free Routing and Free Flight directly involve many such onboard operational and system aspects as to
make it necessary to draw upon the experience coming from relevant European projects and the
expertise of whom is involved in these subjects within Europe. This approach also originates from theneed to avoid duplications of efforts and to better achieve the programme objectives. So it is envisaged
to harmonise and integrate the work.
Mainly addressed to execute operational tests in Free Routing and Free Flight environments, bothsimulated and real ones, Mediterranean Free Flight is an operational programme. Taking into account
that some connected ATM R&D programmes to free routing and free flight are already completed, or
under way, it is also advisable to make an extensive use of the available acquired results.The MFF Partners are part of some co-operation activities that are being either undertaken or already
under way, concerning important European programmes (both the Commission and Eurocontrol’s).
The MFF programme is co-ordinate by ENAV and the Partners’ consortium comprises AENA, DNA,ENAV, EUROCONTROL, HCAA, MIA, NATS, SCAA-LFV.
The Programme will last 5 about years and is split into two main phases. The Programme contains 8
main Working Areas (WA):
WA 1 - ManagementWA 2 - MFF Operational requirements and procedures
WA 3 - Technological framework and Operational scenario
WA 4 - Simulation TrialsWA 5 - Flight Trials
WA 6 - Validation
WA 7 - Operational Benefits and Safety CaseWA 8 – End Results
The Mediterranean Free Flight Programme will start with the survey of users’ expectations and presentair traffic constrains to define operational requirements and procedures for the future implementation
of free flight in the Mediterranean area. The mentioned requirements and procedures will then
matched with current CNS technologies to obtain the specifications for an integrated Ground-Airbornetest bed system able to assess the feasibility of free flight in the Mediterranean area.
Using the defined specification, a real test bed will be implemented, real time simulation will be
carried out and flight trials will be executed. En-route airspace with low-density level of air traffic isthe intrinsic operational location for MFF flight trials.
The programme will also cover Validation, Operational Benefits and Safety Case aspects and
activities. The analysis of the data obtained during the simulations and airborne tests will provideindications that will make it possible to verify and validate:
- how to apply flexible airspace management;
- the operational procedures for transferring separation responsibilities from ATM to pilots andvice versa;
- air safety implications;
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- an improvement in flight schedules;
- the type of training necessary for controllers and pilots in a free flight environment.
The results of studies and validation trials will be contained in the final report and be presented at thenational and international level together with the possible recommendations for implementing free
flight in Mediterranean area and in other areas with characteristic similar to those present in the
Mediterranean scenario.In a later stage, with the support of the European Commission it will be exploited the possibility to
achieve co-operative agreements with boundary Mediterranean countries (Tunisia, Libya, Egypt).
Mediterranean Free Flight is targeted to allow more flexible and direct routings over the Southern andEastern Mediterranean, while maintaining flight safety and increasing economic efficiency.
This target would generate the following expected positive spin-offs:
ð To eliminate the bottlenecks in the air-routes with Europe, by adopting common operationalprocedures allowed by CNS/ATM system;
ð To provide Europe with new more direct, non-congested routes towards African and Middle East
countries;ð To support trade growth and human capital mobility in Mediterranean area by making flight safer
and more efficient;
ð To support local economies by applying the results of the programme as useful guidance regardingthe deployment of new ANS infrastructure/facilities, wherever beneficial or necessary.
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3.2 NEAN Update Program (NUP)
Introduction
NUP (North European ADS-B Network Update Programme) is a TEN-T DGVII European Project. It
is the follow-up of two previous projects: NEAN (North European ADS-B Network) and NEAP(North European CNS/ATM Application Project), reviewed in section 2.8.
The main partners are Swedish CAA (LFV), German CAA (DFS), Danish CAA (SLV), ScandinavianAirlines (SAS), Lufthansa, Aérospatiale Matra Airbus and Sofréavia/DGAC. Other partners through
work packages and so called “Tiger Teams” are Icelandic CAA, Arlanda Airport, Paris Charles De
Gaulle Airport (ADP), Air France, Air Canada, Nav Canada, British Helicopter and Maastricht UpperArea Control (UAC). NUP co-operate closely with Eurocontrol and in specific its’ ADS Program,
through a Memorandum of Co-operation.
The project is split into two phases, phase 1 focusing on planning and development and phase 2 on
implementation and operational or pre-operational use. Phase 1 started in August 1998 and lasts until
June 2001. Phase 2 is planned to start in July 2001 and last for 4 years.
ADS-B is the core component in NUP to enable such applications, while components such as TIS-B,
FIS-B and DGNSS is also used. Most of the applications are related to ASAS as an enabling functionto allow enhanced procedures and delegation of separation assurance. NUP uses VDL Mode 4 data
link to support these air/ground CNS applications.
Below, status of NUP Phase I is briefly summarised as of October 2000.
Objectives
The main objective of NUP is to establish a European ADS-B network based on global standards, with
certifiable applications and equipment supporting new ATM concepts that can be put into operation.Operational requirements aim for increase aircraft throughput while improving safety, regularity and
cost structure. Solutions aim to support gate-to-gate operations (all phases of flight) and all user
groups.
NUP phase 1 is focusing on planning and development with the objective of preparing implementation
of infrastructure and development of pre-operational or limited operational use in NUP Phase 2.
Pre-requisites
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Pre-requisites for NUP were:
• User driven, collaborative development;
• Use of data broadcast concepts for ADS-B, FIS-B, TIS- Ground based Regional AugmentationsServices (GRAS).
• Applicability to ASAS
• User driven, collaborative development• Use of data broadcast concepts for ADS-B, FIS-B and TIS-B
• Operational concept according to the work done by ADS-B Airborne Architecture Task Force
• Use of VDL Mode 4 standard and concept.• Use of new generation of Airbus aircraft(318-340) as a basis for studies and simulations
Organisation and development model
NUP is organised in Work Packages and Tiger Teams. Work Packages are of both operational and
technical nature, whilst Tiger Teams are operational focused. NUP is lead by Swedish CAA (LFV).
ATM Operational Concept
FrankfurtEnhanced VisualAcquisition - EVA
ParisA-SMGCS
NiceVFR/IFRintegration
ReykjavikNon-Radar AirspaceASAS
StockholmStation KeepingApproach/ Departure
North SeaHelicopter TrafficExtended surveillance
MaastrichtATC AutomationComplex airspace
Airborne ArchitectureAerospatiale/AIRBUS
Ground ArchitectureSwedish CAA
Broadcast ServicesDFS
RequirementsSolutions
Tiger Teams
Figure 7. NUP Phase 1 Development Model
Tiger Teams
One of the major activities within NUP is the definition of “Applications and procedures”. The goal is
to identify some ADS-B based applications driven by operational needs and justified by benefitsanticipated by the partners. The approach taken is to develop applications and procedures in local
teams looking at different phases of flight, and later in the process to merge the various requirements
and procedures. These teams are called “Tiger Teams” and involve some ATM actors (i.e. controllers
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and pilots). The establishment of the different teams have taken some time but at the end, seven Tiger
Teams have been created, each of them addressing an application identified by the users.
Tiger Team Application Description / objectives
Stockholm /
Arlanda
Delegated Airborne
Separation for Approach,
Take-Off and Climb-Out
More accurate and finally reduction of the separation in time
closer to the runway occupancy time by delegating the
responsibility for separation assurance from ATC to flight crews
under certain conditions. Key procedure applied is different
forms of Station Keeping (SK).
Frankfurt Extended Visual
Acquisition (EVA)
Extension of the current visual traffic acquisition prior to executing aninstrument approach applying visual separation on final. The flight crew usesthe CDTI to allocate and track the preceding aircraft more effectively,allowing reduced weather minima.
Paris /
Charles De Gaulle
A-SMGCS -
Enhanced Surface visual
Acquisition (SEVA)
The goal is to enhance surveillance to provide the controllers
with a more accurate and more complete knowledge of the
ground traffic, hence enabling an improved traffic control
service. In addition it could be envisaged to also work on the
use of a CDTI on the ground to improve the pilots traffic
situational awareness.
Nice Enhanced Visual
Acquisition for see-and-
avoid applied to IFR/VFR
compatibility
Improvement of the IFR/VFR compatibility in classes D and E
airspace through the use of an airborne Traffic Situational
Awareness application, based on the use of ADS-B, additional
broadcast technologies and a CDTI
Maastricht UAC Delegated Airborne
Separation in en-route
airspace
Delegation by a controller to the aircrew of a cluster of two or
more aircraft for the responsibility to maintain an assigned
horizontal separation in managed airspace through the definition
of the Cluster Control Concept (CC).
Copenhagen,
North Sea
Helicopter surveillance in
non-radar airspace
Surveillance of helicopters flying from land to oil platforms in
the North Sea.
Reykjavik In-trail climb and in-trail
decent in non-radar
airspace.
Improved procedures in oceanic airspace focusing on in-trail
climb and decent.
Table 2 Tiger Team organisation
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The figure below shows how the different Tiger Team Applications incontinental airspace fit to the gate-to-gate concept.
TAKE OFF CLIMB CRUISE DESCENT APPROACH TAXIING TAXIING
SEVA
SK
EVA
CC
SEVA
SK
Figure 8. NUP Applications gate-to-gate coverage.
Explanation for figure above:
SEVA Surface Enhanced Visual Acquisition (Paris Charles De Gaulle)
SK Station Keeping (Stockholm Arlanda)
CC Cluster Control (Maastricht UAC)
EVA Enhanced Visual Acquisition (Frankfurt)
##
In specific relevant for its’ Application Development, top-down, by the “TigerTeam”, resulting in
OEDs (Operational Environment Definitions) and supporting material from e.g. cockpit and ATCsimulations. The below bullet points summarise the main applicable points of their work.
– ASAS Applications
– Certification of ASAS Applications– Simulations of cockpit and ATC involved in ASAS applications
Certification process
Lead by the Certification work package 8, Operational Safety Assessment (OSA) is performed on the
Tiger Team Applications. The OSA follows the methodology developed by RTCA-SC189 andEUROCAE WG53 for end-to-end certification of data link based applications, also identified by
SICASP to be the preferred methodology for ASAS application. In short, each Tiger team define its’
application in an Operational Environment Definition (OED) which is the basis for the OperationalHazard Analysis (OHA). OHA are all in progress for the NUP applications and by the end of NUP
phase 1, SPR (Safety and Performance Requirements) and an ASOR (Allocation of Safety Objectives
and Requirements) and Certification Plans for each Application will be produced. The tiger Team
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applications and OED and OHA outcome will be used by Eurocontrol ADS Program who will conduct
Cost-Benefit Analysis of these applications.
The Tiger Teams and OEDs is a way of splitting the gate-to-gate concept into nearer-term pieces with
local benefit focus. Through the OSA and a “join” of the applications into a “generic OED”, the pieces
are then fitted together to form a gate-to-gate solution.
In NUP Phase, initial Functional Hazard Analysis (FHA) and system safety analysis (SSA) are done
for the air and ground segments based OED/OHA and the air and ground equipment developed,supported by involved industry.
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3.3 AFAS / MA-AFAS
THE AFAS PROJECT
The growth of civil air traffic (5% in time of recession, 8% in 1998) is pushing the current ATM
systems to its breaking point while the future air navigation system (FANS) group mandated by ICAOproposed some new approaches based on the use of new CNS and ATM techniques adopted in 1991,
the programme for its implementation was delegated to the national civil aviation authorities. It is now
urgent to launch an important initiative for the European airspace that implements some of thoseFANS capabilities which are expected to provide the necessary capacity and flexibility needed for the
high density air movement in Europe where the additional stress and greater aircraft numbers will also
require a notable increase in safety in order to maintain today absolutely safety level.
The European ATM system is characterised as a continental, high density airspace with radar
providing position as the sole means of information to the controller. The European problem isincreased by the diversity of means that each individual states has developed as well as the lack of
capacity (it can be noticed here the difference with U.S. domestic airspace where the en-route airspace
has enough capacity whereas the restriction is in the airport TMA - source C/AFT and NAS).
To improve the capacity of the system there is a need for feedback to the different actors of the system
(pilots, airlines operational centres, controllers, planning system…) of data relative to the real situationthat would allow the system to cope with the real time evolution of the traffic. Such a system is
expected to rely increasingly on advanced capabilities provided by airborne and ground automation
systems requiring data exchange and management of timely and accurate air traffic, flight information,navigation and surveillance data in all operational domains.
The changes needed to the current European ATM System can be briefly characterised by:
• Provision of more efficient use of airspace by using free routeing and accurate navigation• Provision of automatic communication to automatically update the airspace utilisation, including
fully automated handovers between ATC sectors
• Planned routing requiring 4D performance to more accurately schedule arrivals• Provision of facilities to provide pilot and controller with improved situation information,
particular with respect to traffic information
• Reduction in weather related diversions
While the short-term proposal utility such as Mode S Enhanced Surveillance are now being rejectedby the users, it is necessary to propose as outlined in this proposal a step where the integration of some
promising technologies will be validated in its global air-ground required performance context, proven
to be economically viable and industrially achievable in a certain timeframe.
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Such a proposal paving the way to the setting of regulations and commercial motives is likely to allow
the suitably equipped aircraft to operate in the European dense air traffic areas.
AFAS will concentrate on the air-ground Data Link communication in the Future CNS/ATM
operational and technological context.
The AFAS project addresses the requirements of Key Action 2.4 , entitled New Perspectives in
Aeronautics, Technology Platform 4 ("More Autonomous aircraft in Future ATM systems"). It aims at
integrating available results into a unique European solution that will be an answer to above statedrequirements. AFAS should be seen as the first step in achieving the airborne components of the
functionality set out in the ECAC ATM 2000+ document. The main work areas explored by AFAS
include :·-Define and propose an achievable ATM operational scenario for the European airspace, that will be
inter-operable with ground segments and will yield a potential benefit in terms of capacity and safety
increase, while maintaining or even enhancing the level of costs benefits ·-Efficient use of capacity and reduce delays ·
-Draw benefit of previous and current projects in the ATM area ·
-Select the most promising CNS/ATM technologies that will be integrated in an avionics package ·-Define, develop, integrate and verify this avionics package supporting ATM functionalities · Check
inter-operability issues on test benches fully representative of European operations in 2005, from both
functional and operational (e.g. mixed aircraft) perspective ·-Evaluate pre-operational concepts in view of establishing a standard that can offer benefits (capacity,
safety, cost) and propose an alternative to US standards dominant position ·
-Assess the impact of these new functions on pilot in terms of Human Factors including situationawareness· Demonstrate the viability of concepts based on real-life 2005 scenarios
3.3.1.1 Description of project-results• A validated CNS avionics package meeting the requirements of a high-density airspace ATM
system, ready for certification process, to be exploited by avionics suppliers as a first release in
their new CNS product line.
• Operational concept as supported by this avionics package.
• Studies on cost effectiveness of these operational concepts, that aim at demonstrating the potentialbenefits in order to encourage airlines and ATM Service Providers decision-makers in applying
these new concepts.
• Metrics will be defined for subsequent data collection and interpretation.• Incentive policies will be defined and promoted for moving to CNS/ATM
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• An assessment of the impact of such requirements on current airborne systems. this will help
airframe manufacturer to integrate these systems in the cockpit, as well as airworthiness
authorities in charge of certifying CNS systems and aircraft• Plans for certification and for system-level Verification and Validation activities will be produced
• A definition of the role of the crew and of the share of responsibilities between pilot and
controller, as well as human factors aspects.• The outcome will consist in full requirements for these new operational procedures that will be
mostly useful for airlines, pilots, airframe manufacturer, avionics suppliers and airworthiness
authorities.
3.3.1.2 Technical approachIn order to achieve these objectives, the AFAS project is divided into the following work areas: ·Selection of ATM operational concepts that can demonstrate short term benefits, mainly traffic
planning concepts with their impact on efficiency and capacity. This selection will be performed by
actors of the airborne segment (industry, airlines) in close connection with ground ATM experts, froma list of candidate CNS (Communication Navigation Surveillance) functionalities. The selection of
AFAS ATM Functionality will be based on choice and trade-offs concerning the different options
relating to system performance, costs, capabilities and the resolution of various constraints andrequirements including: - AFAS shall consider short haul aircraft s flying in the core European
airspace (high density),
- AFAS functionality shall make use of mature 1 CNS technologies supported by stable ICAO(SARPs) and RTCA/EUROCAE (MASPS) standards in the timeframe of 2005 to ensure systems and
procedures interoperability - Aircraft fitted with the AFAS airborne system shall be compatible with
non-equipped aircraft as the future ATM network will have to accommodate a broad mix of aircraftcapabilities. Inputs coming from on going projects like TORCH and NUP will complement the CNS
functionality analysis. Development of avionics packages meeting upcoming CNS 2005
functionalities, such as improved ATC data-link capabilities, improved 4D-flight plan predictionaccuracy, based on existing CNS components. The work includes defining a functional architecture,
assessing performance and safety, interfacing with onboard systems including human interface
aspects, and defining test cases as well as pre-operational scenarios. · Validation of these packages byperforming a set of testing activities that range from equipment testing up to full integration testing
between a cockpit and an ATC centre. This activity covers setting up tools that enable performance
assessment. · Preparation of pre-evaluation activities that need to be conducted on a real aircraft fleet,with a careful definition of evaluation objectives and logistics required to large-scale flight campaign.
This activity will be defined in close collaboration with ATM service providers and airlines. ·
Investigation of airworthiness and standardisation issues that will prepare future standards. ·Monitoring and interaction with standardisation bodies in the CNS/ATM field The chosen
experimental platform is the European A318/ A319/ A320/ A321 family with 1000 aircraft in service
today (and a perspective of 1300 additional ones) among which over 600 in Europe today. This type of
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aircraft has been chosen since it will maximise the benefit for a subsequent implementation on revenue
aircraft. : · The impact on capacity and safety will be optimised with more than 600 short-range
aircraft · Both European aircraft manufacturers and European suppliers will draw benefit and increasetheir market share. · It will be easier to define the basis for a European standard with a full European
solution. The main innovation of the AFAS project lies in the fact that, the airports and ATC service
providers are working together with other stakeholders (airlines, industry…) to include the airbornesegment as an essential part of global ATM system This will be done within a large scale integration
project which aims at demonstrating the feasibility and viability of this global solution to meet the
objectives..
3.3.1.3 The project teamThe main European civil aircraft manufacturer leads a consortium of European parties featuring: ·Regulatory Bodies, Civil Aviation authorities and ATM service providers acting for the deployment
and safety of ATM in Members States · Airspace users involved primarily in crew and operation
aircraft fleets Air transport industry that design, manufactures and qualifies CNS/ATM equipment(Aircraft manufacturer, Equipment sector, Ground equipment sector) · SMEs working in the ATM
domain · Research centres specialised in ATM activities and providing valuable results from previous
projects
3.3.1.4 ObjectiveThe technical approach focuses on equipment planned to be used in managed airspace, as this is stillprevailing in Europe, and also is the foundation for the introduction of autonomous aircraft capabilities
(e.g. FMS capabilities), for which an implementation depends on results of a validation process to
come. The avionics package will therefore be designed in such a way that there is growth potential forembedding additional services.
With the advocated approach, both capacity and safety concerns are covered in a realistic perspective
by more direct routes, reduced delays and environmental benefits. The airline policy not to planbeyond the declared airport capacity highlights the fact that the system imposes such limits. The
advanced avionics package will provide the basis for alleviating such ‘artificial’ limitations. AFAS is
to propose a major innovative step towards reaching the perspective of a collaborative, flexible andversatile ATM. The experimental system developed within AFAS will be a first transition step
towards improving overall European ATM operations, providing a mature short-term solution.
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More Autonomous Aircraft in the Future ATM System (MA-AFAS)
3.3.1.5 Introduction
The More Autonomous Aircraft in the Future ATM System (MA-AFAS) programme addresses the
requirements of Key Action 2.4 New Perspectives in Aeronautics, Technology Platform 4. It aims totransform European research results into practical operational ATM procedures with the potential to
radically improve the European ATM scenario in the near term (from 2005 onwards). By selecting and
validating key Airborne elements of CNS, and defining their economic benefits and certificationrequirements, the research will enable more autonomous aircraft operation in the European ATM
system.
The improvements must be capable of being fitted to existing aircraft so this project will focus on the
ATM solution required for aircraft retrofit. It shall use the ATM and ground requirements, ground
infrastructure and operational scenarios, as defined and reviewed by users (such as airlines and ATSproviders) in WP1 – Operational Concept, as a basis. The retrofit avionics solution will be designed
and developed to meet this baseline (under WP2 – Avionics Package) and demonstrated within
representative future ATM environments (under WP3 – Validation). The capabilities to be validatedwill be confirmed at the start of the programme, however the following will be specifically addressed:
• Validation of GNSS (with ground and space based augmentation) procedures for approach using
4D flight path control.• Evaluation of airborne 4D flight path generation for integration with ground based flight path
planning
• Validation of ADS-B (using VDL Mode 4) with airborne display of traffic (CDTI) and separationassurance algorithms
• Integration of airborne taxiway map and data linked clearances
• Evaluation of flight deck HMI improvements to support 4D flight path generation and monitoringin a more autonomous environment
• Integration of the full ATN stack/VDL mode 2 in the airborne environment to support AOC and
ATC communications using ODIAC defined standards
3.3.1.6 MilestonesThe MA-AFAS milestones will be :
• Formulation of an achievable common operational concept which builds upon EC and Eurocontrol
Research in the functional areas of Air-Ground and Air-Air data-links, SBAS and GBASapproaches, 4D flight path generation and guidance, CDTI and ASAS
• Validation by Avionics Package Definition and trials
• Verification of communication loop using MA-AFAS defined Operational Procedures
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• Verification that Ground infrastructure can support mixed capability aircraft
• Establishment of a safe strategy implementation, based on economic benefit, Standards and
World-wide Agreement• Development of User Buy-in
3.3.1.7 The project teamThe MA-AFAS team includes avionics and communication suppliers, research centres, SMEs, service
providers, policy makers and airlines, therefore ensuring all key parties are represented in the design
and development of this avionics package. The team encompasses a good mixture of nationalitiesincluding Austrian, British, Dutch, German, European, French, Irish, Italian, Portuguese, Spanish and
Swedish.
The project will be run by a strong management team from a leading avionics supplier with vast
experience in managing large integration programmes. The management structure will be hierarchical
with day-to-day responsibility delegated to work package leaders who will report regularly to theProject Manager. Project control will be maintained using automated tools with regular reviews to
ensure consistency of milestones with progress.
Community Added Value is obtained by pulling together expertise from different companies across
different countries in Europe, which otherwise would not occur, to allow for the design, development
and validation of an avionics package for the European ATM system. The results will lead to reducedair movement costs through greater route efficiency. In addition, there is the potential product
development and supply of retrofit equipment to airlines. Improvement in European Technology
Progress will be achieved by furthering the combined community knowledge and experience on futureavionics solutions for the global ATM environment and ensuring the solution will have a strong
European focus.
3.3.1.8 Technical approachThe key technical and scientific approaches that will ameliorate the ATM limitations are seen as:
• Air-Ground data-links• Air-Air data-links
• SBAS and GBAS GNSS
• 4D Flight Path Generation and Guidance• CDTI
• ASAS
Air-Ground Data-links will enable high integrity communication between specific aircraft and ATC
controllers. They will allow data to be directly loaded into key systems, such as the FMS, with little or
no pilot intervention, avoiding any mis-interpretation and leading to reduced pilot workload (eg by
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automating communications frequency changing and position reports) . However, this direct end to
end communication will remove the party line effect of today’s air-ground communication and so care
will need to be taken to ensure that crew situational awareness is not reduced. Also, the timeliness andpracticality of tactical commands being issued via this data-link will need to be considered. Trials of
Mode S, SATCOM and VDL Mode 2 Air-Ground data-links have already been carried out using a
range of partial to full ATN stacks. This project will use trials experience from ProATN, PHARE andPETAL 2, to further the development and validation of these data-links.
Air-Air Data-link is the enabling technology for ADS-B (using VDL Mode 4). It will allow, givensufficient bandwidth, the broadcasting of aircraft information to surrounding traffic. This information
can then be used for collating into a traffic display, such as CDTI, and as the input to station keeping
and separation assurance algorithms, such as ASAS. Extensive trials over Northern Europe have beencarried out under the NEAP and NEAN projects demonstrating use of Air-Air data-links. By linking
into the NUP programme, MA-AFAS will build on its results and aid in verification of the approach
for pre-operational use.
By improving the integrity of the GNSS aircraft navigation, the dependence of the aircraft on ground
support at airfields in poor weather reduces. This will enable aircraft to carry out precision and non-precision approaches, and land at less well equipped airfields. Also, with increased integrity, spacing
between aircraft can be reduced whilst still maintaining safety. Activities in America and Europe
(such as WAAS, LAAS, EGNOS) have developed SBAS and GBAS technology to enable higheraccuracy and more importantly, higher integrity to be obtained from GNSS navigation. By building
on MA-AFAS partners’ involvement in development of procedures for GNSS approaches and their
links with EGNOS, the MA-AFAS project will be able to further the validation of using GNSS and D-GNSS for more autonomous approaches.
4D Flight Path Generation and Guidance will allow for more accurate prediction of estimated times ofarrival / times over waypoints. This will enable better forecasting of traffic patterns, particularly
within the busy TMAs and it will enable the aircraft to meet any block time requirements with greater
reliability (assuming no excessive ATC intervention). Partners’ experience in today’s fixed and rotarywing FMS, AFMS, AATMS, 3FMS and PHARE programmes will be used as a basis from which to
design, develop and validate an avionics package that provides 4D flight path generation and
guidance. Trials will be carried out to verify the accuracy of the time, altitude and positionpredictions, and identify the benefits that can be achieved by greater predictability of aircraft
movements.
Traffic information presented to the aircrew, via CDTI, will allow the crew to gain good situational
awareness of the local traffic and therefore, the likely conflicts / resolution actions required and
flexibility available in current route re-planning. On the ground or on final approach, this would also
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have the capability to provide information about airport surface traffic, allowing the crew to be more
confident that no traffic conflicts exist. ASAS will be the first major step towards an autonomous
aircraft. It will allow the aircraft to maintain its separation with surrounding traffic and resolvepotential conflicts, without the intervention of ATC. Based on the Freer programme and Free Flight
studies currently being undertaken by several partners, MA-AFAS will use the display formats which
have already been assessed by users (such as airline pilots and ATC controllers) and the algorithmstrialed in simulators upon which to design, develop and test traffic information displays and separation
assurance algorithms in flight trials.
These technologies, which are in-line with the EC and Eurocontrol concepts, will form the building
blocks that this project will use to achieve the following innovative elements :-
• Validation of GNSS (with ground and space based augmentation) procedures for approach using4D flight path control.
• Evaluation of airborne 4 D flight path generation for integration with ground based flight path
planning• Validation of ADS-B (using VDL Mode 4) with airborne display of traffic (CDTI) and separation
assurance algorithms
• Integration of airborne taxiway map and data linked clearances• Evaluation of flight deck HMI improvements to support 4 D flight path generation and monitoring
in a more autonomous environment
• Integration of the full ATN stack/VDL mode 2 in the airborne environment to support AOC andATC communications using ODIAC defined standards
These innovations are the 1st stage in the steps leading to an autonomous aircraft capable of operatingin a distributed ATM environment. A major advantage of taking these steps is the improved ATM
system robustness gained from using this distributed approach.
3.3.1.9 Scientific and Technological ObjectivesThe scientific and technological research objectives include :-
• Demonstrating a more autonomous aircraft concept• Proving Air-Ground loop, in terms of communication and procedures
• Proving that Ground infrastructure can support mixed capability aircraft
• Updating and modifying standards to pave the way for global seamless ATM• Generating and validating Operational Procedures, showing that the avionics package gives
benefit in the ATM environment and is compatible with cockpit HMI requirements
• Preparing for pre-operational validation of the avionics package, including exploitation activities• Demonstrating the combined European strategy to future ATM is :-
• achievable
• gives benefits in terms of efficiency, capacity and safety,
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• upgradeable to meet future demands
• can form the basis of a global ATM environment
3.3.1.10 Technical BaselineThe MA-AFAS programme will provide an avionics package, fitted to experimental aircraft and
simulators and evaluated within the future ATM environment using representative ground platforms,including shadow operational ATC centres, AOC centres and, if available, Gate to Gate 2005.
The basis of the avionics package is the existing Marconi Canada CMA 900 product which has alreadybeen installed, as a retrofit item, into Boeing 747 and MD-80 aircraft, for operation with several major
European airlines. The CMA 900 comprises an enhanced Flight Management Computer,
Multifunction Control and Display Unit and a GPS antenna.
Building on the baseline CMA 900 product, MA-AFAS will use partners’ experience in AFMS,
AATMS, 3FMS and PHARE, to provide expertise in adding 4D enroute capability to the MA-AFASavionics package. This capability is then expected to be validated extensively within simulator and
flight trials.
Using partners’ experience gained from providing ASAS elements to AVENUE and involvement in
the FREER programme, it is expected that the MA-AFAS avionics package will provide ASAS
functionality which will be developed and validated within the programme. Assessments will becarried out to determine human factors issues and user acceptance, in addition to the technical and
procedural operational evaluation carried out during simulation and flight trials.
The MA-AFAS team has experience in taxi management through its partners involvement in
programmes such as TARMAC. MA-AFAS is anticipated to provide, develop and validate a taxi
management, clearance and guidance system, whilst maintaining close links with the BETAprogramme.
MA-AFAS, through its partners, in particular through the UK CAA NATS, has strong links withEGNOS and now the GALILEO programme. This experience, together with other background
knowledge such as SBAS and GBAS SARPS development, will form the basis for the precision
approach (up to CAT 1), landing and take-off trials using SBAS and GBAS.
Development and validation of data link communications will be continued within Europe by MA-
AFAS, in conjunction with other European programmes such as PETAL 2 and NUP. MA-AFAS willbuild on experience gained from such programmes as FARAWAY, NEAN and ProATN as well as the
experience gained by key partners on-going work, such as SC-TT’s development of a VDL Mode 4
transceiver and Airtel-ATN’s provision of the first fully compliant ATN Router to ARINC.
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Human factors and HMI issues will be addressed throughout MA-AFAS avionics package
development, verification and validation, using, in particular, research partners and user communityrepresentatives as well as user forums, pilots and controllers to evaluate how effectively it has been
addressed. MA-AFAS will set up and maintain links with other HMI related projects, such as DIVA
and 3FMS, through the MA-AFAS HMI Co-ordinator, as well closely monitoring, and whereappropriate, being involved in, the HMI thematic network programme.
3.3.1.11 Overview of the project Work PackagesThe proposed work has been broken down into 5 areas :-
• Management
• Operational Concept• Avionics Package
• Validation
• Operational Support
Package for pre-Package for pre-operationaloperationalvalidation &validation &
The interrelation of these areas is shown in Figure 9. This work breakdown represents the standardapproach to the lifecycle of a research programme.
This programme shall commence with developing an operational concept to link the air-groundrequirements and procedures, focusing particularly on the European perspective. Airborne ATM
functions will then be selected for implementation, and reviewed by users, together with the scenario
under which they will be demonstrated. From this, the avionics package will be designed, developedand tested using specifically developed test platforms. Then, the avionics package will be verified and
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validated against flight simulators and trials aircraft using appropriate ground and communication
infrastructure. During this time, the operational procedures developed for its effective use within the
ATM will be verified and validated. Finally, the cost benefit of the avionics package will be assessed.The effect of its implementation on standards will be identified and new and modified standards will
be proposed for adoption. An exploitation plan will be produced that will define the steps required to
take the avionics package into the market place, and an implementation plan written which willdescribe the phases required to obtain pre-operational validation of the avionics package, in
preparation for in-service operation.
3.3.1.12 ObjectivesThe retrofit avionics package would be applicable to any aircraft wishing to take advantage of the
autonomous ATM environment. It addresses the airborne issues required to tackle the projectedcongestion problems predicted for the European core ATM environment within the next 10 years. By
validating the requirements and facilities provided by the on-going and proposed European and
American ATM programmes, it will lead towards :-• Aircraft being flown more efficiently, through better route planning, selection and execution,
(leading to less pollution and lower noise)
• Improved timeliness of the aircraft, through integrating 4D flight plans and flying precise 4Dflight paths, thus allowing conflict detection from the planning stage to be updated during the
flight and taken into account in the scheduled arrival time and sequencing
• Maintained or improved safety due to better knowledge of aircraft’s position and intention (fromADS and ADS-B (using VDL Mode 4)) and more accurate 4D guidance
• Increased throughput at airfields (in conditions of low visibility) resulting from cockpit display of
taxiways, clearances and other traffic• Greater flexibility in approach (and departure) design using enhanced GNSS resulting in improved
traffic flows and less pre-take-off delays at airfields.
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3.4 EMERTA
The European Commission Fourth Framework programme covers all the Research and TechnicalDevelopment (RTD) activities carried out by the European Union during the period 1994-1999.
Nineteen specific programmes are part of the Fourth Framework programme. Project EMERTA
(EMERging Technologies, opportunities and impact on ATM) is part of the Transport programme.Project EMERTA was initiated in response to the Air Transport Research Task 4.1.2/19 in the fourth
call for proposals by the European Commission (EC) Fourth Framework programme.
The work of Project EMERTA is centred on the implications of two emerging technologies andassociated concepts for aeronautical use, Next Generation Satellite Systems(NGSS) and Automatic
Dependent Surveillance-Broadcast / Airborne Separation Assurance System (ADS-B/ASAS).
Next Generation Satellite Systems Study
The EMERTA’s NGSS study-programme contained four main work packages:• WP2.1 – Emerging NGSS
• WP2.2 – Safety Assessment
• WP2.3 – Costs and Instituitional Issues• WP2.4 – Long Term Benefits
The first three work packages are concerned with the application of NGSS technologies in the nearterm (2000 to 2005 timeframe). At the onset of the EMERTA work-study, the NGSS operational
scenario dealt primarily with Europe’s peripheral areas, where NGSS can provide a service where
traditional ground infrastructure is not available.
WP2.1 was conducted in four parts:
• WP2.1.1 identified ATM and AOC application requirements.• WP2.1.2 identified the expected capabilities of emerging NGSS.
• WP2.1.3 investigated considerations relating to the avionics required for emerging NGSS.
• WP2.1.4 matched the perceived capabilities with the identified requirements.
In WP2.2 a safety assessment was conducted of a particular scenario involving NGSS mediated
communications. The selected scenario involved 2 or more aircraft on the same route and same flightlevel longitudinally separated via ADS monitoring outside radar control, in the Southern
Mediterranean airspace. The scenario has the benefit of increasing that route’s ATM capacity. The
TOPAZ safety assessment conducted in the WP 2.2 includes the selection of an ATC operationalsituation
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Work package 2.3 included investigations of both costs related to the introduction of NGSS and
Institutional aspects including a brief account of events which have affected the NGSS industries over
the last 5 years or so since the inception of NGSS work by the ICAO AMCP panel.Work package 2.4 considered the long term (beyond 2005) and investigates future ATM concepts
which may enabled by new communication services supported by advanced communications systems
such as the emerging NGSS. A first cut at defining requirements for both voice and data transmissionin a top-down “clean-sheet approach” is also presented.
The key findings of the EMERTA NGSS study can be summed up as follows:
NGSS are being assessed in the current SATCOM context under which the INMARSAT AMSS is
used on a daily basis on about 2000 aircraft. So far the use of this SATCOM technology has beenrestricted to oceanic/remote areas, on account of both high airborne equipment costs and
communication charges. This may explain why AMSS has so far experienced a rather slow uptake of
its safety related service - AMS[R]S.NGSS, since their inception in the mid 1990s, have given rise to expectations of bringing a better and
cheaper AMSS service to the aviation community. These expectations have not materialised at the
time of writing of this report.In 1999, ICAO, at the 6th AMCP meeting, formally endorsed the conceptual feasibility of the use of
commercial NGSS for the provision of AMS[R]S and subsequently, in year 2000 decided to develop
appropriate SARPs needed for deployment world-wide. These SARPs are two-tier, comprising (a) ageneric set of high-level regulatory and service definition standards applicable to all systems and (b),
system-specific detailed specifications of performance and interface characteristics with airborne
avionics and ground ATM/AOC infrastructure.However with the recent demise of IRIDIUM, the NGSS Industry effort needed to develop the second
level has stopped until such a time another system's promoter, formally offers AMS[R]S and is willing
to contribute the significant level of effort within ICAO's panels required for such a development.They will also need to assist RTCA/EUROCAE in generating the usual aviation industry standards -
MASPS and MOPS.
There are serious doubts about the long-term availability of the AMS[R]S service of satellite systemsmainly developed to serve a bigger evolving mobile communication markets, beyond the specific
needs of civil aviation - which is a small but difficult market in comparison.
With the demise of IRIDIUM, there is only a single LEO/MEO NGSS project planning to offerAMSS/AMS[R]S; namely New-ICO. It is worth noting that this New-ICO offer is based upon
granting access to its new packet data transmission service, making use of the TCP/IP protocols suite
starting with the AOC provision. If such an offer succeeds, there will be pressure on ATS authoritiesto move towards, or be compatible with, the TCP/IP protocols for ATS communications in addition to
AOC, instead of deploying the ICAO-standardised ATN which is based on the OSI protocols.
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The ESA/SDLS concept based on the use of geostationary satellites and dedicated to the provision of
AMS[R]S is now proposed as the next generation AMSS with the capabilities to serve high-density
airspace in addition to oceanic/remote areas. A technical demonstrator is currently under industrialdevelopment, as a first step to establish this new concept credibility.
The AMS[R]S data market, over Europe by year 2008 is estimated to be in the range of 20 to 60
millions EURO, at a the charging rate of 0.1 EURO per kilobit and under avionics equipage varyingfrom 30 to 90 % of the commercial aircraft fleet.
The feasibility and options for cost-sharing should be investigated (a) with other satellite systems and
(b) between aviation users and industry suppliers, including by setting-up PPP (public privatepartnership) financial and institutional arrangements. Specifically ways of sharing costs with other
satellite systems such as GALILEO should be looked into.
The following short-term programmes are considered to be of value to the future of ATM:Aeronautical Frequency Review: Development of a consensus of the frequency requirements for ATM
in to the future and adoption of strategy, co-ordinated at European level to ensure continuous access to
RF spectrum for both AMSS and terrestrial systems.Develop a back-up RT Strategy using SATCOM Voice: Trials of existing SATCOM voice services as
a backup voice system.
Experimentation and use on pre-operational basis of NGSS demonstrators, i.e. of the New-ICO andESA/SDLS types in order to both asses technical performance and the impact on operational
personnel’s (ATC and pilots) acceptability and work-procedures.
Looking into the feasibility , both technical and economic, of a combined safety-relatedcommunication and satellite navigation mission, specifically on the European GALILEO GNSS
ASAS Feasibility and Transition Issues
Work package three considered the feasibility of the early introduction of ASAS applications in
European Airspace and the associated transition issues. The work was conducted as three separate butrelated tasks:
WP3.1.1 considered the ASAS applications in terms of technical feasibility and transition issues
including benefits, costs, standardisation and institutional issues. The selected scenarios are analysedin terms of the supporting technology, data availability and operational implementation. The
immediate benefits of the introduction of these applications are identified, and an initial assessment of
costs is made.WP3.1.2 considered the availability of the data required for the ASAS applications in terms of the
avionics fitted on the commercial fleet.
WP3.1.3 considered the requirement for, and use of, a traffic information service as a means ofsupporting ASAS applications in a mixed equipage environment.
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The report concludes that the early adoption of ASAS applications for enhanced situational awareness
and pair-wise tactical co-operative applications is not only possible but indeed could be beneficial
within the next few years – assuming that the remaining technical and institutional issues are resolved.In terms of the initial implementation of ASAS the ‘transition’ is key since this is not only the
environment in which the initial use of the first ASAS applications will be introduced but, as
discussed, is likely to be of indefinite duration and therefore the environment in which ASAS willcontinue to exist.
The fundamental reason why a ground based traffic information service (TIS(-B)) will be needed is to
support a partial ADS-B equipage environment which is unavoidable in the transition period. The ‘gapfiller’ role can also provide some backup in the event of ADS-B equipment failure. As well as this
there is the issue of the integrity of ADS-B surveillance information and whether this is sufficient for
it to be solely relied on in ASAS applications, this implies an ongoing role for TIS-B in the ASASenvironment.
The data available on board the majority of aircraft is sufficient to support the requirements of the
chosen initial ASAS applications. In particular the use of TIS(-B) to support a partial equipageenvironment means that those aircraft which have the data available, primarily the modern jet aircraft,
will be able to take part in ASAS without the need for older aircraft to equip. There are a number of
non-aircraft state parameters such as call sign, aircraft type and emergency status which need to bemade available either through the FMS or via the airborne equipment which will support ASAS on the
aircraft. This is discussed further below.
The introduction in the relatively near term of some initial ASAS applications is feasible given that anumber of prerequisites are satisfied, these can be split into technical and institutional issues:
Institutional Issues:• The initial applications must be chosen carefully.
• The relevant procedures must be developed.
• Issue of separation responsibility must be resolved.• The benefits must be demonstrable and sufficient to justify the required investment.
Technical Issues:• A specification for TIS(-B) must be finalised.
• For the chosen data-link medium the technical issues must be closed.
• Suitable airborne equipment must be developed, certified and available.• The aircraft which are to be involved must be suitably equipped.
• Appropriate supporting ground systems must be implemented.
• CDTI functionality and related HMI issues must be addressed.
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As has been discussed earlier the choice of initial ASAS applications is crucial to the feasibility to the
introduction of the ASAS concept. The two applications chosen for analysis in EMERTA both have
key features which allow them to be candidates for early implementation.The Enhanced Visual Acquisition (EVA) application is one where ASAS is used essentially without
consequence, it is a VFR tool on which there is no reliance other than being used to improve the see
and avoid principle. While this means that this application is easily certifiable, and therefore a goodcandidate for early implementation, it also has the problem that because it is only a VFR application
the benefits to be gained are unlikely to drive equipage in the air transport community. GA pilots may
find the potential safety enhancement to their normal VFR operations a benefit which will inspireinvestment by the individual, but for an airline operating almost exclusively IFR it will not.
The Station Keeping on Approach (SKA) application is by it’s nature a local application and does not
require full equipage in the environment, any suitable equipped aircraft can take part in thismanoeuvre, which, if the benefits of such a procedure can be demonstrated is likely to encourage
equipage. Even with the need for TIS(-B) the local nature of the application means the investment on
the ground will not be too great to provide the system at key airports. The issues of responsibility arealso more straightforward than is potentially true for other ASAS applications.
The benefits that an aircraft operator will gain from the investment required to fit with the equipment
necessary to take part in ASAS applications will need to be clearly identified. The total benefit fromthe initial applications must be sufficient to drive equipage. It is therefore important to identify all of
the potential near term ASAS applications before beginning the first stage of implementation.
Illustrative procedures have been developed for the SKA application. This procedure will need to beformalised in order for the manoeuvre to be implemented and procedures developed for any other
ASAS applications being considered.
In terms of the technical issues, the choice of medium for TIS(-B) is discussed and the three maincandidates (VDL Mode 4, 1090 MHz and UAT) are all capable of supporting the system. There are
certain technical issues which must be resolved in each of the media in order to be able to support the
TIS(-B) system. Once the TIS-B specification is finalised airborne equipment which is preferably bothADS-B and TIS-B capable needs to be developed. Clearly then aircraft need to equip but this relates to
the institutional issues. Given the need for a TIS(-B) system to support ASAS implementation the
ground equipment to provide this service must be provided. As discussed, certain ASAS applicationsare, by their nature, local and so a single airport providing a TIS(-B) could enable the first
implementation of ASAS for such applications.
CDTI functionality, in terms of the way surveillance information is presented to the pilot and whattools will be implemented to aid the participation in ASAS manoeuvres, needs to be developed further
from the human factors and technical perspective. The onboard processing, which takes the
surveillance inputs and processes them prior to display or use by ASAS tools, is also key and theremust be further development of these functions. It may be through this equipment which may be
included in the CDTI or the ADS-B/TIS-B transceiver that the parameters mentioned above could be
made available for broadcast.
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4 Related projects
4.1 PETAL
PETAL (Preliminary Eurocontrol Test of Air/ground data-link Project) is a EUROCONTROL project
aimed to demonstrate advanced air/ground data-link functionality to be used in the European upperairspace.
Data-link functions and services designed within PETAL were specifically targeted at reducing
controller and pilot workload, frequency congestion and operational inefficiencies surrounding routinevoice communications in a congested airspace. Controllers and aircrew made direct, operational use of
data-link to more efficiently request, deliver, and acknowledge flight level clearances, direct routings,
and sector/sector voice communications transfer instructions.
The project was first conceived in May 1994. PETAL equipment development and testing was
completed in April 1995, with 46 operational flights subsequently conducted between May 1995 andApril 1996.
The primary objectives of the project were to initiate direct controller and aircrew contact with anair/ground data-link communication technology in a real time operational environment, to validate
European operational requirements and gain experience in implementing data link in an ATC Centre
system.
PETAL involved only one data-link equipped aircraft at any one time in an ATC sector. Also, the
project resulted in a number of recommendations for the future work and requiring the continuationand expansion of this operationally oriented approach to air/ground data-link.
Thus PETAL-II, the second in the series of Eurocontrol operational air/ground data-link trials wasestablished. The project began in September 1996 and will be completed in 2002.
The overall aim of PETAL-II is to obtain first-hand, factual data on the operational benefits,requirements, human factors, procedures and problems associated with using air/ground data-link in
busy continental European airspace.
PETAL-II’s use of a ‘live’ ATC environment to link current air traffic controllers, aircrew, industry,
and air/ground data-link developers, has proven to be an extremely effective means of developing and
validating European operational concepts, requirements and procedures. The project provides anessential step in the operational implementation of data-link, by following the repeated lesson that
operational procedures and requirements should come first, and technology second.
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4.2 AFMS
The Flight Management System (FMS) of today has introduced operational advantages and significantcost savings through offering the possibility of an automatic, fuel-efficient flight from take-off to
landing. However, the FMS with its high level of automation has changed the pilot’s role
considerably. This has caused dominant problems with respect to human factors. Furthermore, thepresent FMS technique is not able to meet the requirements of the future CNS/ATM (Communication,
Navigation, Surveillance, Air Traffic Management) scenario. For that reason, this project concentrated
on the development and evaluation of a demonstrator for an Advanced Flight Management System(AFMS). The objectives of the AFMS programme were the development and demonstration of a set of
advanced Flight Management Systems (FMS) which will be able to meet the requirements of the
future Air Traffic Management (ATM) environment. The main emphasis was on ensuring that flightmanagement functions were compatible with the future European CNS/ATM environment, both in the
short term (around the time frame of 2005) and the medium term (from 2005 to 2020). This required
the FMSs to handle flight planning and negotiation via a data link, which in turn led to the need togreatly enhance the Human Machine Interface (HMI) to ensure good crew situational awareness of
these additional functions. To address the HMI, FMSs were produced that could textually and
graphically display and edit the flight plan.
Since the project partners are deeply involved in research work in this field the approach was to base
development on pertinent systems such as the "Experimental FMS" (EFMS) from the PHAREprogramme or the German "Cockpit Assistant System" (CASSY). The development was further based
on the outcome of the study project "AFMS" (APAS-Task 2.1) in which the functional requirements
for an AFMS were consolidated. Therefore, the final project objective was to develop an AFMSdemonstrator, based on the EFMS prototype, the CASSY prototype and the results of the AFMS study,
and to validate this demonstrator in a simulated ATM environment.
The project objective has been attained by a 37 month project that covered the following phases:definition of functional requirements using the results and specifications from previous FMS related
programmes performed by the partnership (PHARE-EFMS, APAS-AFMS, CASSY)
development of software code for the different modules of a demonstratorintegration of the modules into the flight simulators and validation of the demonstrator in a simulated
ATM environment
exploitation of the results with regard to new products for European avionics industry
During the consolidation of the user requirements, it became apparent that there were a number of
differing requirements emerging for the short term, i.e. the next 5 to 10 years, the medium term of 10to 15 years and for differences between fixed wing and rotary wing aircraft. Consequently it was
decided to develop and validate two fixed wing AFMS demonstrator versions, targeted at the short
term and the medium term future operating environment. A further version of the AFMS demonstrator
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would concentrate on helicopter aspects. This development was based on a common system design
and harmonised by putting certain emphasis on different aspects of the AFMS. This approach was
adopted as it was not expected that a single demonstrator would be able to meet all the differentaspects of the operational ATM environment, whilst commonality and upgrade paths between the
demonstrators was maintained as much as possible.
The short term fixed wing system comprises of a DZUS-sized integrated control, display and
navigation unit with a built-in active matrix colour display and the respective software modules
integrated in this unit. This hardware box - also named NFS-5000 - has been developed under theTelematics Application Programme (TAP) projects, AATMS and FARAWAY. The NFS-5000 realises
functions of an advanced flight management system. Through its advanced, object-orientated
graphical user interface it allows the pilot to easily enter and modify flight plans. Aircraft position datacan be received from a flight simulator (or an external GPS receiver and various aircraft systems).
The NFS-5000 has been designed as a FMS for aircraft that are not equipped with integrated systems.The functionality and performance of the NFS-5000, therefore, have been designed to serve the short
to medium range FMS aircraft retrofit market (turboprops, business jets and light air transport jets).
For this reason, the short-term planning and guidance functions concentrate on today’s situation withadditional capabilities for automated flight plan editing (autorouting), integration of radar vectors in
the flight plan (vectoring), as well as integration of uplinked flight plans and flight plan constraints but
without trajectory negotiation capabilities. With regard to the crew interface, the NFS-5000 follows aconcept to realise an integrated control, display and flight management unit with a graphical display
on this CDU, intended for aircraft which are not equipped with integrated avionics systems. For the
evaluation the short term demonstrator was adapted in the ATTAS simulator at DLR in Braunschweigand was tested by 10 pilots in accordance with the created scenario flight from Boscombe Down to
Amsterdam Schiphol.
The medium term fixed wing AFMS demonstrator represents a software prototype system supporting
4D flight planning, i.e. generating a 4D-trajectory with respect to aircraft position, altitude and time,
and negotiation of a 4D-trajectory with ATC/ATM facilities by means of a data link connection. Theunderlying operational mode refers to strategic planning, but depending on the time horizon applied
may include tactical control advisories as well. However, immediate action requests from ATC/ATM
or AOCC for emergency situations are out of the scope. The demonstrator software is based on thePHARE1 EFMS development, with FMS functionality enhanced by additional and/or extended flight
planning, flight monitoring and 4D-trajectory negotiation modules and sub-modules. The crew
interface concept represents a means for the pilot to operate the demonstrator system by direct access
1 Programme for the Harmonised Air Traffic Management Research in EUROCONTROL - The objective of PHARE is to organise, co-
ordinate and conduct studies and experiments aimed at proving and demonstrating the feasibility and merits of a future air-groundintegrated air traffic management system in all phases of flight.
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via touch-pad input on Navigation Display and Advanced CDU, i.e. the role of the crew as manager of
the airborne part of a future ATM system and overall system integrity are supported. The crew
interface software utilises the basic ideas of the PHARE EFMS, but is further developed regardingintegrity of the particular flight management tasks, aircraft supervision and 4D-trajectory negotiation.
The demonstrator supports combined operation of different display devices presenting identical
information in an alphanumeric or graphic format, on CDU and ND, respectively. This demonstratorwas integrated into the ATTAS Experimental Cockpit simulation environment and tested by 14 pilots
by means of two to three scenario flights from Boscombe Down to Amsterdam Schiphol.
The medium term rotary wing AFMS provides full auto 4D (i.e. longitude, latitude, altitude and time)
flight planning. It uses an accurate aircraft model in combination with the latest available weather data
(comprising of wind speed and direction, temperature and QNH) to accurately predict the helicopter’sflight plan. Due to the accuracy of the prediction, the crew are able to give more reliable and accurate
arrival time estimates. The use of a special approach generator allows the helicopter to land at
unprepared airfields. Also, using the fuel model contained within the 4D flight planner, the crew areable to compare the fuel efficiency and arrival times of one route against another to determine the
most cost effective option for a selected cost index. The medium term rotary wing AFMS further
provides 4D guidance to the active flight plan. The guidance has 2 modes of operation, continuousmode, which is where the guidance continually tries to keep the aircraft exactly on the flight plan, and
event driven mode, which is where the guidance only makes corrections when the aircraft is going
outside a pre-defined tolerance from the flight plan. By allowing the guidance to operate in 2 modes,the system is able to take advantage of the differing accuracy with which the aircraft needs to be flown
depending on the phase of flight. Therefore, for phases of flight such as approach, the aircraft will be
guided in continuous mode, maintaining maximum adherence to the flight plan and so maximisingsafety. In phases of flight such as late climb, cruise, and early descent, the aircraft will be guided in
event driven mode, allowing the aircraft to be flown more efficiently and with greater passenger
comfort as the changes in autopilot will be minimised.
The AFMS demonstrator also supports data-link communications with the ATC, allowing strategic
negotiation of flight plans between the crew and the ATC during the flight. It also provides AutomaticDependent Surveillance (ADS) via data link, allowing the ATC to monitor the aircraft’s progress and
have an indication of its intent by knowing its next waypoint together with estimated time of arrival
and distance to it. The medium term rotary wing AFMS also comprises a more integrated HumanMachine Interface (HMI) than standard FMS. It comprises a Navigation Display which has a cursor
control device, as well as a more conventional Control and Display Unit (CDU), although with a task
oriented page structure. The Navigation Display is a map display upon which the flight plan and flightpath information is overlaid. The cursor control device allows the crew to graphically edit the flight
plan in conjunction with function and line select keys. The Navigation Display supports track up and
north up displays for monitoring and editing the flight plan, and it also supports profile displays to
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allow crew to assimilate the vertical aspect of the flight path. Time information is given textually at
pertinent points along the flight plan. By linking the Navigation Display and the CDU together, a
selection or edit on one device will be reflected almost instantaneously on the other.
The simulation trials for this demonstrator took place in Eurocopter’s fixed base helicopter simulator.
The following main results have been achieved in the frame of the AFMS project:
- Short-term AFMS demonstrator (NFS-5000)
- Medium-term AFMS demonstrator- ATN compliant AOC and ATC ground system demonstrators
The NFS-5000 as the first result is a technology demonstrator for an AFMS with 4D flight planning
and guidance capabilities, and advanced crew interface concept and ATN compliant data-link
capabilities. The main conclusions from the evaluation were that the system works without any majordifficulties, although the overall performance for response times was too slow. Overall the pilots
envisaged that they could use such a system in the future. The most innovative aspect certainly lies in
the fact that the NFS-5000 integrates advanced flight management functions including ATNcompatible data-link applications in one box. This enables a cost-effective use of an ATN end system
especially in the retrofit and general aviation sector. It opens a realistic opportunity since with this
concept all participants in the ATM environment can be reached and fitted with the respectiveequipment leading to growing market opportunities for the respective avionics suppliers.
The second result addresses medium term applications and is an AFMS technology demonstratorcomprising of 4D Flight Planning capability, 4D Guidance capability, communication with Air Traffic
Control and Airline Operations Centre via data-link and enhanced Crew Interface by use of the
Navigation Display in combination with the Control and Display Unit. The medium term AFMS istargeted at the Air Traffic Management environment of 2015, with particular focus on the densely
populated airspace, typical of the European situation. However, the medium-term AFMS will give
operational benefits in today’s environment with features, such as improved calculation of Top ofDescent point to allow more efficient descent profiles.
As a result of the test and evaluation runs in the frame of the AFMS project it can be stated that theoverall system concept of the medium term AFMS proved to be robust without major operational
problems. Due to the advanced crew interface concept it could be shown that pilot acceptance is
improved, even though operated in the much more complex and challenging ATC environment of theyear 2015. Moreover, the evaluation runs proved that training times may be reduced considerably, as
the crew interface is much more compliant to the pilot's view of the environment. Consequently, the
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medium term AFMS met the operational goals as a demonstrator suitable as basis for product
development.
As part of the project, two ground simulators have been developed to validate the implementation of
the PHARE ATN compliant data-link services for both ATM (CPDLC, 4DTN, ADS applications) and
AOC (AOC application). These simulators allow rapid prototyping and operational validation of theproposed data-linking activities including the uplinking and downlinking of AOC and ATM messages
and protocols. Furthermore, the ATN-like communication protocol libraries permit easy testing of
peer-to-peer communication either at application or transport compliant levels. One of the main resultsin this context lies in the realization of AOC services with a high potential for subsequent industrial
application decision aid systems and error reporting environments dedicated to airline companies.
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4.3 TELSACS
The TELematics for Safety Critical System (TELSACS) project focused on the interoperable use ofairborne and ground safety nets. The aim was to enhance the overall level of safety and reduce the
disturbing effects by taking advantage of new concepts and technologies. In particular, the air/ground
and air/air exchange capabilities.
The project was started in January 1996 and ended in August 1999.
Today, decision making regarding anti-collision between aircraft relies on information coming from
two systems:
1. Short Term Conflict Alert (STCA), on the ground, which alerts controllers on any current orpredicted violation of separations standard
2. Airborne Collision Avoidance System (ACAS), aboard equipped aircraft which is a last resort
equipment, performing surveillance around the aircraft and advising avoidance manoeuvres incase of threat.
As these systems work independently, users experience drawbacks such as unwarranted alert messagesor contradictory decisions. Also, the analysis of conflicts presenting ACAS advisories (sometimes
preceded by STCA alerts) shows that pilot and controller perceptions of the situation are very
different.
TELSACS research aimed at specifying the evolution which is necessary to improve the
interoperability of STCA and ACAS.The first part of the project consisted in three main phases:
1. users' requirement collection, achieved through surveys performed with controllers, pilots and air
companies2. definition and specification of the safety net including ACAS and STCA
3. development of a demonstrator enabling performance measurement and evaluation .
The second part focused on validation and recommendations for safety standards
TELSACS objectives were derived from end users’ requirement collection, and it appeared that the
primary goal was to enhance user awareness, both on the ground and on board.
TELSACS specified a demonstrator implementing the ground and airborne enhancements issued from
users’ requirements, which were likely to improve STCA/ACAS interoperability.The demonstrator was based on a pre-operational platform allowing users to experiment and validate
the system in a representative way.
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The primary goal of TELSACS demonstrator was to prove that it was possible to improve controllers'
and pilots' understanding of the situation and consequently to reduce the risk of interference between
ground and air collision avoidance management, thanks to additional information exchanged byair/ground and air/air data link.
The evaluation of the concept proposed in the TELSACS Project was carried out performing twodifferent kinds of analysis.
The first analysis was based on a statistical approach allowing the definition and execution of a largenumber of simulation exercises characterised by several values of input and control parameters. This
analysis was more dedicated to the evaluation of performances, based on "objective criteria", that were
in effect measures of the parameters that characterised safety. Measures were done during simulationsusing a dedicated tool, and demonstrations.
The second kind of analysis used to evaluate the benefits of TELSACS was based on the interpretationof the results of real time simulations performed involving Air Traffic Controllers and pilots. This
analysis was performed with the TELSACS demonstrator. This “subjective" validation of the system
by users, by means of experimentation and questionnaires, was dedicated to:• to get their feeling on enhancements provided by TELSACS and on the way the additional
information is presented,
• to evaluate the enhancement in terms of safety and reduction of work load.
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5 CARE ASAS ACTIVITY 1 workshop
The CARE ASAS Activity 1 consortium also organised a workshop to discus the findings of ActivityOne. For this workshop the main stakeholders with respect to the ASAS were invited. The workshop
was organised at Eurocontrol headquarters in Brussels on October 2nd. The participants were asked to
read the draft report, listen to the findings and provide the consortium with feedback based on theirown domain knowledge. Thus any shortcomings of the draft report would be identified and corrected
with the final version of the reports. During the workshop each main partner presented their findings
after which questions could be asked and remarks could be made. A total of 22 participants werepresent representing different organisations such as pilot-unions, airline organisations, research
establishments, authorities, and air traffic control providers. During the day active discussions took
place and the main items are listed below:
A chapter should be included with recently started projects, since some of them were highly relevant
to the ASAS domain (the chapter is included within this report).
The scope of this report had to be outlined within the introduction (introduction has been rewritten).
The annexes were not compatible with each-other (annexes have been rearranged).
As general conclusions remarks were made regarding the lack of a road-map for the introduction ofthe ASAS. During the on-following discussion it was suggested that the Eurocontrol OCD document
described a well accepted end-state for such a road-map.
Another general conclusion made was that the studies showed a large diversity in the type of Human
Factors data produced and that perhaps a common set of metrics, definitions and scenarios should be
developed or recommended by CARE ASAS.
Finally a discussion about the lack of economic data resulted in the remark that that would be to soon
or perhaps irrelevant because ASAS could well be the only solution to the present problem of the everincreasing traffic density and the resulting delays and other ATC problems. Because of this possible
strategic importance an cost benefit analysis would not serve its purpose.
More remarks were made during the workshop, but it would be outside the scope of this report to list
them all. However most remarks were taken into account while editing the final version of this report.
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6 Summary of results and discussion
This chapter will summarise the results found so far by the consortium. The main points found will be
shown tables after which the results are briefly discussed. First however a classification of the projects
is found in table 1 across the different types of ASAS categories. The project EMERALD and CENAfirst defined the different categories of ASAS applications:
• Autonomous, whereby aircraft have full autonomy regarding their separation assurance;
• Co-operative, whereby the separation responsibility has been partly delegated to the aircraft by thecontroller;
• Situation Awareness, whereby the ASAS only serves to increase the situation awareness of the
aircrew.
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very high density)Table 3 Classification of projects
The table shows that a lot of work has been done in the ASAS categories “autonomous” and “co-operative” and only a few projects could be classified under the ASAS category “ situation
awareness”. The reason for the latter could be that they were all studies done in real flight (see
table…) and that therefore the most simple category was chosen (without any consequences regardingresponsibility etc.), Another striking result is that all the studies dealing with autonomous ASAS
applications only cover cruise flight. No study dealing with autonomous aircraft in areas other than
cruise have been done to this date. Generally the phases of flight other than cruise are studied with co-operative ASAS concepts.
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6.2 Technological Issues
CNS requirements
projects Requirements and specs
EMERALD ADS-B
Mode S and VDL mode 4Specs for:
• latency
• range• availability
• integrity
• update rate
CENA ADS-B / TIS-B
Requirement for air-to-air data-link
Requirement for intent
FREER FAST EACAC (min. req.)
ADS-B ADS-B or TIS-B
Air-to-air data-link position and velocity infoIntent
Specs for:
ranges
NEAN ADS-B / TIS-B
VDL mode 4
FARAWAY ADS-B / TIS-BVDL mode 4
GPS
SUPRA ADS-B / TIS-B
NLR ADS-B / TIS-B
Position and velocity info only
Specs for :• ranges
• update rateTable 4 CNS requirements
The table above shows that most studies do provide some form of CNS requirements. The most
complete set was given by the EMERALD project. All studies in the table above assume some form ofADS-B with or without TIS-B. Most studies assume the VDL mode 4 system as the enabler. The
projects studying the more elaborate applications also state that some form of intent (and air-to-air
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data-link) is needed. The exception is the NLR study, which devised a system to circumvent the intent
requirement.
Decision support tools
projects CDTI CD&R
3FMS Map
Map +along track profile
Map +along route profile
Deconflicting of FMS route
Modified voltage potential
EMERALD ASAS info integrated with ACAS
info
Specs for:• Station Keeping
• Closely Spaced Par. App.
• Autonomous appl
MAICA GEARS
Little differences found between:
• Vertical, Horizontal , both• Resolutions
• Variable look ahead time
GLASGOW Dynamic programming algorithmbased on distributed artificial
intelligence
CENA CDTI with relative speed line Force field techniqueA* algorithm
FREER Numerous CDTI studies ranging
from basic to elaborate withprediction capabilities and nogo
zones
Conflict detection based on airborne
HIPSResolution based on EFR
NEAN Basic CDTI
FARAWAY Basic CDTI
SUPRA Basic CDTI
NLR CDTI with track profile andPredASAS capability
eliminating requirement for intent
Conflict detection based on positionand velocity
Resolution based on
Modified voltage potentialTable 5 Decision Support tools
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The table above shows perhaps the most diverse set of results. A large number of studies have
developed their own CDTI format and many different conflict detection and resolution algorithms
have been studied. Perhaps this could be a focus for CARE ASAS to try to converge the number ofpossibilities by means of a large comparative study.
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6.3 ATM Performance Issues
Performance Issues
projects Performance issues
EMERALD Safety assessment showed the requirement for a dual channel ASAS
TORCH Improvement of TMA efficiency expected through reduced controllerworkload and improved pilot autonomy
MAICA Predictions of traffic density in 2015
Predictions of number of conflicts per acft per hour (<1 in worst case)
CENA Sector Capacity Improvement method developed showing a possible
increase of capacity of 12.2 %
Operational Hazard Analysis tool developed
NEAN Expected capacity, safety and efficiency improvement based on pilots
comments
NLR Showed that ASAS could deal with densities of up to 9 times the presentEuropean densities,
Table 6 Performance issues
The table above show in general that a benefit is to be expected from ASAS applications. The range of
the effects differs between the studies (which perhaps are related to the chosen concept and or
algorithms). Striking is that the MAICA project predicts that the number of conflicts per aircraft perhour is below 1 in the worst case.
Transition Issues
projects Transition issues
EMERALD Discusses all political complications of reaching full equipage.Expects local applications being fielded first.
GLASGOW Developed COAP algorithm between free flight sector and
TMA entry point
NEAN Relies on TIS-B for transition period
FARAWAY Relies on TIS-B for transition period
NLR Relies on TIS-B for transition period and studied several ATMconcepts with different densities and levels of equipage.
EMERTA (project still
ongoing)
Discusses transition road-map with TIS-B through the
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Transition issues are mostly dealt with by the introduction of TIS-B. The EMERALD project however
shows that the transition could be a very major issue for the introduction of the ASAS. The EMERTA
project is also added to the table because highly relevant work was just reported with their 4th
workpackage and which is closely related to the findings of the EMERALD project.
Flow Management aspects
Only the University of Glasgow took flow management into account by means of a model optimisinginbound and outbound air traffic flow and en-route air traffic flow using a scheduling algorithm.
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6.4 Human factors issues
projects HF issues
3FMS Subjective data collected from aircrew in simulator on:
• Concept• CDTI
• CD&R
FREER Subjective data collected from aircrew and controllers with real flight on:• Concept
• CDTI
• CD&R
NEAN Subjective data collected from aircrew with real flight on:
• Concept
• CDTI• CD&R
FARAWAY Subjective data collected from aircrew in flight on:
• CDTI
SUPRA Subjective data collected from aircrew and controllers with real flight on:
• Concept
• CDTI
NLR Objective and subjective data collected from aircrew and controllers with
simulator on:
• Concept• CDTI
• CD&RTable 8 Human Factors issues
Striking is the fact that most HF data are base on questionnaires and subject opinion. Only the NLR
has published other HF data, such as eye-point-of-gaze, reaction times etc. This could be explained bythe fact that most of these studies require vast resources to set-up an environment simulating or
emulating an ASAS application and that adding items such as objective measure systems would add to
this cost. However many HF handbooks warn against the use of only subjective, expert opinion.
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6.5 Economical Aspects
No studies have shown data on economical aspects. However statements were made during the CAREASAS activity 1 workshop, that perhaps this is too early, because with a strategic issue such as ASAS,
cost benefit analyses are:
• Very hard to perform due to the high number of unknown variables• Sometimes irrelevant because the system could well be the only way in which the future predicted
traffic growth could be dealt with.
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6.6 Institutional aspects
Projects procedures certification
EMERALD Detailed procedures for:
Station Keeping
Closely Spaced Par. App.Autonomous Operations
TORCH Detailed procedure for
Station Keeping in busy TMA
CENA Detailed procedure for
ASAS crossing procedure
FREER Detailed procedures forAutonomous flight with EFR
Crossing and passing manoeuvres
Sequencing and merging in TMA
NEAN Certification of ATM services
with VDL mode-4
FARAWAY Certification of ATM serviceswith VDL mode-4
NLR Detailed procedures for
Autonomous flightTable 9 Institutional aspects
The table above shows that many projects have described in detail procedures for ASAS applications.The chosen applications however vary quite largely showing the large area of possibilities, which are
introduced by the ASAS.
Certification of an ASAS system is described within the NEAN and FARAWAY projects.
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7 Conclusions and Recommendations
This report shows as a main conclusion that the ASAS is being studied very actively within Europe.That fact is not only shown by the projects discussed within this report (a number of which are still on-
going), but also by the number of projects recently started (chapter 3). These studies produce a large
amount of data, as is shown by this report. However the diversity between the studies are very large asis shown by the previous chapters.
Many different ASAS concepts are being studied, all with different assumptions about the way ahead.The issues involved are to be structured.:
Recommendation 1: It is recommended that CARE ASAS should derive a road-mapconcerning the introduction of the ASAS. Activity 4 could be modified such that the present
objective application selection would include a road-map concerning the introduction of the
ASAS. The Eurocontrol OCD document (see annex J) could be regarded as a well acceptedend-goal for this purpose.
The most striking diversity is seen regarding the applied CD& R algorithms:
Recommendation 2: It is therefore recommended to include an extra CARE ASAS activity to
compare the different CD& R rules. This activity should take the work performed by theRTCA SC 186 into account, since they are presently producing material regarding CD& R
algorithms for the ASAS.
The different ADS-B implementations are presently covered by an EUROCONTROL ADS
programme. Therefore no recommendation regarding ADS-B is made.
This report shows that human factors are studied in a very diverse way, which could be a factor in the
different outcome of the studies regarding CDTI implementations and ATM performance results:
Recommendation 3: The third recommendation concerns a common set of metrics to be used
for Human Factors issues. CARE ASAS activity 2 has as an objective to develop a common
set of metrics, definitions and scenarios and it is recommended to do the same regardingHuman Factors measures. This would probably mean an extra activity for CARE ASAS.
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Annex A. Reference documents of the reviewed projects
This annex contains the list and description of documents that EEC received from the consortium,
WP5.5 report – Research and Technical Development (RTD) Plan for ASAS Concept Development,
vers 3.0, 5 march 1998Volume 6 – Assessment of Emerging Technologies: the specific case of ADS-B/ASAS, rev 2, oct
1998.
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TORCH documents
WP2.1 - Functional Description of the Current European ATM System.WP2.2 – Definition of the Operational Concept.
WP2.3 - Identification of the Operational Concept Components and Elements
WP2.4 - Identification of Enablers
WP2.5 - Operational Concept Definition and Breakdown for TORCH
WP 4.3 – Analysis of a concept of Station Keeping applicable to TMA.
MAICA documents
WP1 – Possible changes in Future ATM system
WP2 – Definition and objectives of simulationWP3 – Simulation and Development
WP4 – Final Report
GLASGOW University Papers
• Colin Goodchild, Miguel A. Vilaplana and Stefano Elefante “Co-operative Optimal Airborne
Separation Assurance in Free Flight Airspace”, USA/Europe ATM R&D Seminar,
Napoli 13 th-16th June 2000.• Colin Goodchild, Miguel A. Vilaplana and Stefano Elefante “Research explores operational
methods that could support a global ATM system”, ICAO journal April 1999.
• Colin Goodchild, Miguel A. Vilaplana and Stefano Elefante “Co-operative Optimal AirborneSeparation Assurance in Free Flight Airspace”, ICAO journal November/December
1999.
CENA documents
[ce1] ONERA, “Etude d’algorithmes d’évitement pour la navigation aérienne, rapport final”,Rapport technique RT 3/8944 SY, Novembre 1995.
[ce2] ONERA, “Etude d’algorithmes d’évitement pour la navigation aérienne, dossier d’évaluationde la logique”, Rapport technique RT 6/8944 SY, Septembre 1996.
[ce3] ONERA, “Etude d’algorithmes d’évitement pour la navigation aérienne, documentationtechnique de la logique”, Rapport technique RT 5/8944 SY, Septembre 1996.
[ce4] ONERA, “Etude d’algorithmes d’évitement pour la navigation aérienne, rapport de synthèse”,Rapport technique RT 8/8944 SY, Decembre 1996.
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[ce5] F. Casaux, B. Hasquenoph, “Operational use of ASAS”, USA/Europe ATM R&D Seminar,Saclay, France, 1997.
[ce6] K. Zeghal, “Air Traffic Management: Support for decision making optimisation –automation”, AGARD, May 1997.
[ce7] J.-M. Alliot, N. Durand, G. Granger, “FACES: a free-flight autonomous and coordinatedembarked solver”, USA/Europe ATM R&D Seminar, Orlando, 1998.
[ce8] B. Bonnemaison, F. Casaux, T. Miquel, “Operational assessment of co-operative ASASapplications”, USA/Europe ATM R&D Seminar, Orlando, 1998.
[ce9] K. Zeghal, “A review of different approaches based on force fields for airborne conflictresolution”, Guidance, Navigation and Control Conference, Boston, August 1998.
[ce10] K. Zeghal, “ A comparison of different approaches based on force fields for co-ordinationamong multiples mobiles”, International Conference on Intelligent Robotic System, Victoria,October 1998.
[ce11] T. Miquel “A theoretical assessment of sector capacity improvement due to ASAS concept”,CENA Note NT99523, July 1999.
[ce12] A.D. Zeitlin, B. Bonnemaison, “Managing Criticality of ASAS Applications”, USA/EuropeATM R&D Seminar, Napoli, 2000.
SICASP and ADSP documents
[ce13] SICASP/6-WP/44 “The ASAS concept” - Appendix A on the Report on Agenda Item 6 –Montreal, February 1997.
[ce14] F. Casaux, SICASP/WG2-WP2 “The ASAS crossing procedure”, Honolulu, October 1997.[ce15] SICASP/WG 2 ASAS sub-group “EMERALD view on ASAS / ACAS compatibility and the
use of ASAS templates”, June 1998[ce16] SICASP/WG2-WP2 “Use of ADS-B data for ASAS”, June 1998.[ce17] SICASP/WG 2 “Operational and technical considerations on ASAS applications”, January
1999[ce18] T. Miquel “ ASAS studies at CENA”, Toulouse, April 1998.[ce19] B. Bonnemaison, F. Casaux, “ASAS concept considerations”, ADSP/5 WP, Montreal,
October 1999[ce20] F. Casaux, P. Caisso, E.Vallauri, Y. Sagnier, “ Point sur les travaux de la France sur l’ADS-
B”, ADSP/5-WP, Montreal, Octobre 1999.[ce21] B. Bonnemaison; T. Miquel, F.Casaux, “Airborne Separation Minima”, RGCSP/10-WP,
Montreal, May 2000.
EMERALD documents[ce22] EMERALD, “Identification and classification of potential ADS-B/ASAS applications”,
WP5.1 Report1.0, July 1997.[ce23] EMERALD, “Detailed feasibility assessment of selected ADS-B/ASAS applications”, WP5.2
Report 3.0, November 1997.[ce24] EMERALD, “Research and technical development (RTD) plan for ASAS concept
development”, WP5.5 Report 3.0, March 1998.
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FREER documents
FAST documents
[fr1] V. Duong, E. Hoffman, L. Floc’hic, J-P. Nicolaon, A. Bossu, “Extended Flight Rules to applyto the resolution of encounters in autonomous airborne separation”, EUROCONTROL EECTechnical Note, September 1996.
[fr2] V. Duong, E. Hoffman, “Conflict resolution advisory service in autonomous aircraftoperations”, IEEE/AIAA Digital Avionics Systems Conference, Irvine, California, 1997.
[fr3] V. Duong, E. Hoffman, J-P. Nicolaon, “Initial Results of Investigation into AutonomousAircraft Concept (FREER 1)”, USA/Europe ATM R&D Seminar, Saclay, 1997.
[fr4] V. Duong, “FREER: Free-Route Experimental Encounter Resolution- A solution for theEuropean Free Flight Implementation”, Air Navigation Conference, Amsterdam, September 1997.
[fr5] V. Duong, “FREER: Free Route Encounter Experimental Resolution- Initial Results”,European Aerospace Conference on Free Flight, Amsterdam, October 1997.
[fr6] V. Duong, K. Zeghal, “Conflict resolution advisory for autonomous airborne separation in lowdensity airspace”, Decision and Control Conference, San Diego, December 1997.
[fr7] EUROCONTROL EEC, “FAST: 1999 pilot in the loop evaluation”, EEC Note No 13/00, July2000.
EACAC documents
[fr8] A. Cloerec, K. Zeghal, E. Hoffman, “Traffic complexity analysis to evaluate the potential forlimited delegation of separation assurance to the cockpit”, IEEE/AIAA Digital Avionics SystemConference, St Louis, Missouri, 1999.
[fr9] E. Hoffman, K. Zeghal, A. Cloerec, I. Grimaud, J.-P. Nicolaon, “Operational concepts forlimited delegation of separation assurance to the cockpit”, AIAA Guidance, Navigation andControl Conference, Portland, 1999.
[fr10] E. Hoffman, K. Zeghal, G. Courtet, “ Modeling of the scale of separations in cockpit displaysfor limited delegation of separation assurance”, SAE/AIAA World Aviation Congress, SanFrancisco, October 1999.
[fr11] K. Zeghal, E. Hoffman, J.-P. Nicolaon, A. Cloerec, I. Grimaud, “Initial evaluation of limiteddelegation of separation assurance to the cockpit”, SAE/AIAA World Aviation Congress, SanFrancisco, October 1999.
[fr12] EUROCONTROL EEC, “FREER-FLIGHT, Evolutionary Air-ground Co-operative ATMConcepts (EACAC), Procedures of delegation from the controller to the pilot”, June 2000.
[fr13] K. Zeghal, E. Hoffman, “Delegation of separation assurance to aircraft: towards a frameworkfor analysing the different concepts and underlying principles”, ICAS, August 2000.
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NEAN – NEAP- JANE documents
NEAN documents
The NEAN project was divided into 6 work packages:
Work Package 0: Project EstablishmentWork Package 1: Installation and trials
Work Package 2: Installation and trials - expansion
Work Package 3: Development of ADS-B NetworkWork Package 4: Certification issues
Work Package 5: Data Analysis and Reporting
Related to these work package, the following documents were produced:[ne1] “Work Package 1 – Progress Report”, November 1997[ne2] “Work Package 2 – Progress Report”, May 1999
[ne2.A] Appendix A – Detailed results
[ne2.B] Appendix B – Post Processing Tools[ne2.C] Appendix C – NEANSERV MIB[ne3] “Work Package 3 – Progress Report”, April 1997[ne4] “Work Package 4 – Progress Report”, October 1997[ne5] “Final Project Summary and Conclusion report” May 1999
NEAP documents
The final summary and conclusion report is divided into three volumes:1. Executive Summary
2. Final Consolidated Progress Report with an Appendix and several Annex
3. Final report for Publication
The following documents were produced:
Volume 1:[ne6] “Executive Summary”, June 1999
Volume 2:[ne7] “Final consolidated report progress report-Final report”, June 1999[ne8] “Project definition document- PDD”, January 1998[ne9] “Test methodology”, April 1998[ne10] “Certification roadmap”, February 1999[ne11] “Service description - On ground situation awareness/Taxi guidance, In-flight situation
“awareness”, 1998
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[ne12] “Test plan - On ground situation awareness/Taxi guidance, In-flight situation “awareness”,1998
[ne13] “Evaluation and equipment performance - On ground situation awareness/Taxi guidance, In-flight situation “awareness”, 1998
Equivalent documents corresponding to the other NEAP applications are also available.
Volume 3:[ne14] “Final report for publication- contract AI-97-SC.1180”, 1997
JANE documents
[ne15] DFS Deutsche Flugsicherung GmbH, “JANEX I, First JANE Experiment, Final Report”Version 1.1”, May 2000
FARAWAY documents
The documents were provided by Alenia.
[fa1] Telematic Application programme Transport, “Final Report, TR1025, FARAWAY – Fusionof Radar & ADS data through two WAY data-link”, Version 0.9, July 1998
[fa2] “Specification of the Cockpit Display of Traffic Information”, 1998
SUPRA documents
[su1] “SUPRA User Requirements document”, Version 2.01, July 1997[su2] “SUPRA System Definition Document”, Version 2.00, August 1997[su3] “SUPRA Demonstrator Description”, Version 2.00, August 1997[su4] “SUPRA Trials Report”, Version 2.01, June 1997[su5] “SUPRA Final Report”, Version 1.00, August 1997
TELSACS documents
[te1] TELSACS, “State of the art database directory”, Release 4, September 1996[te2] TELSACS, “User requirements”, Release 1, September 1996[te3] TELSACS, “Specifications”, Release 3, December 1997[te4] TELSACS, “Specification of the pilot HMI”, Release 1, July 1997[te5] TELSACS, “Validation report”, Release 3, September 1999[te6] TELSACS, “Analysis of benefits”, Release 0.2, January 2000
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Annex B. Detailed results of 3FMS project
Here follow some extracts from 3FMS HMI-DD document.
B.1 Detailed description of 3FMS CDTI
Three variants of CDTI are proposed, with different formats of ND.
Variant 1: Map Only
The traffic is displayed on the Navigation Display, in a similar way TCAS displays traffic today. In
contrast with a normal TCAS display, different symbology is used because of the pilots’ separation
assurance task. The extra information consists of :
- ground speed (numerical)- climbing or descending arrow (symbol)
Traffic conflict:
- horizontal track line (always shown)- predicted intrusion of protected zone of target
Ø along current a/c velocity vector (selected mode CDR only)
Ø along active flight plan (managed mode CDR only)- time to intrusion
- resolution to prevent intrusion (selected mode CDR only)
Ø graphical planar vector on the NDØ steering bugs on the PFD and ND
- resolution to prevent intrusion (managed mode CDR only)
Ø modified flight plan (vertical, lateral, combined lateral/vertical) in a graphical and/ornumerical presentation on the ND
- priority status (managed mode CDR only)
Ø give way (predicted intrusion and intruder shown in amber)
Ø right of way (both predicted intrusion and intruder coloured cyan)
Ø not computed (amber predicted intrusion and white intruder), this status normally last foronly a few seconds, i.e. time needed for priority co-ordination between conflictingaircraft
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Using the Display Control Panel the flight identifier, altitude and ground speed of proximate traffic
can be switched on or off.
When a conflict occurs -for the selected mode CDR version- with a time to intrusion of less than 5
minutes, the following sequence of display changes were shown:
1. The position of traffic is shown (in amber);
2. The incursion of the protected zone of the traffic is shown;
3. The traffic resolution is shown on the ND;
4. The resolution will be followed using the MCP whereby the heading and vertical speed (indicatedby bugs on the ND and PFD) will have to be selected by the crew by hand. The most efficient wayof changing the settings during and after a conflict was briefed and trained.
5. When the conflict is resolved the position of the traffic is shown in the colour of the conflict foranother ten seconds;
If during the above sequence the time to intrusion (i.e. time to loss of separation) becomes less than 3minutes, the traffic symbols will be shown in red. For an example of the ND see figure below.
Navigation Display with ‘amber’ conflict (selected mode CDR)
When a conflict occurs -for the managed mode CDR version- with a time to intrusion of less than 10
minutes, the following sequence of display changes are shown:
1. The position of traffic is shown (initially flashing white and its route in amber);2. The incursion of the protected zone of the intruder is shown;
Intrusion ofprotected zoneintruder
Amber, redHDG areas
Selectedmoderesolution
Amberintruder
Actual trackangle
Active flightplan
Steering bug
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3. When the priority status is determined, takes a few seconds, colour coding of the conflict indicates
who has to resolve the conflict, status will be either ‘give way’ (action required) or ‘right of way’
(intruder has to take action and he knows it);4. After selection of the proposed flight plan modification, via ASAS page on the MCDU, the
conflict resolution is shown on the ND as a dashed yellow line (lateral) and/or yellow numerical
constraint (vertical) and as modified flight plan on the CDU;5. During MCDU operations, to activate/erase the modified flight plan and, if required, to complete /
modify / select a proposed conflict resolution, the ND shows the flight plans as acted upon by the
flight crew;If during the above sequence the time to intrusion becomes less than 3 minutes, the conflict symbols
will be shown in red, irrespective of the priority status, together with an increase in aural alerting level.
Immediate action is required. For an example of the ND see figure below.
ND with ‘amber’ conflict and vertical resolution (managed mode CDR)
Variant 2: Map + Along Track Profile with distance axis
Because of the relative importance of vertical manoeuvres a Vertical Profile display is integrated
below the normal Map display. In comparison with the MAP ONLY variant the same information is
also presented in the Vertical Profile display.
Amberintruder
Managedmoderesolution
Intrusion ofprotected zoneintruder
Actual trackangle
Active flightplanintruder
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Since the Map and Profile ranges are the same it is a truly coplanar presentation of the information
elements. The horizontal positioning of proximate traffic, flight plans, predicted conflicts and
intruders’ flight path in the Profile display is derived from their projection on the current a/c trackangle.
Using the Display Control Panel the flight identification, altitude and groundspeed can be switched on
or off. The Map/Profile range (5, 10, 20, 40, 80, 160, 320 xNM) and altitude scale (2.5, 5, 10, 15, 20,25 x1000ft) can also be controlled through the DCP.
The sequence of display changes, for both selected mode and managed mode CDR, is identical to the
sequence described for the MAP ONLY variant. The next figure gives an example of the ND for theseparation assurance task with selected mode CDR algorithms. The figure subsequent shows an
example for the managed mode CDR version.
Navigation Display with ‘amber’ conflict (selected mode CDR)
Intrusion ofprotected zoneintruder
Vertical trackangle, activeflight plan
Selected moderesolution
Amber intruder
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ND with ‘amber’ conflict and vertical resolution (managed mode CDR)
Variant 3: Map + Along Route Profile with time axis
The second Vertical Profile display variant is also integrated below the normal Map display. Incomparison with the ‘Along Track’ Profile mode the ‘Along Route’ variant is based on a slightly
different philosophy. Whereas the Along Track mode represents a truly coplanar presentation the
Along Route mode is designed with the below mentioned philosophy, for Map and Profile display, insupport of the pilots’ navigation and separation assurance tasks:
• global presentation of the 3D position – rough lat/long indication in the Map display (through
relative bearing/distance to well-known areas and points) and a rough altitude indication in theProfile display;
• global information of the actual 3D position relative to the flight plan -- left/right in Map display,
high/low in Profile display;• more precise information about the actual velocity vector relative to the flight plan and a precise
preview of velocity vector changes – heading/track angle in the Map display and vertical speed in
the Profile display
Vertical trackangle, activeflight plan
Amber intruder Intrusion ofprotected zoneintruder
Managed moderesolution
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• vertical speed is used along the vertical axis in the Profile display mainly because the basic
information components of the velocity vector are heading (see the various Map modes) and
vertical speed.An ‘Along Route’ type of Profile display is by definition more a look in the short future than a vertical
depiction of the current situation. Time and distance (of the active flight plan) along the horizontal
axis are therefore interchangeable and also the different flight plans of own ship and intruder have tobe presented differently, presentation along a time line makes it easier to compare them. A
consequence of the Along Route display is that proximate traffic cannot be presented clearly and
unambiguously in the vertical plane.Using the Display Control Panel the altitude scale (2.5, 5, 10, 15, 20, 25 x1000ft) and also vertical
speed scale (2.5, 5, 10, 15, 20, 25 x100fpm) can be set. The Profile range (in time) is not selectable by
the flight crew.The information presented is in itself identical to the other variants, only in a different format.
The sequence of display changes is also identical to the sequence described for the other variants. Note
however that only the managed mode CDR version was used in combination with the Along RouteProfile display. The following figure gives an example of the Navigation Display.
ND with ‘cyan’ conflict and vertical resolution (managed mode CDR)
B.2 Conclusions and Recommendations of the human-in-the-loop evaluation
Conclusions• Pilots are positive with respect to free flight in general.
Active flightplan
Cyan intruder
Managed moderesolution
Intrusion ofprotected zoneintruder
Actual verticalspeed
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Free flight is seen as a promising solution for future traffic separation although pilots feel a lot of
details need to be worked out before an operational system is available which operates in all
situations and fall-back options are sufficiently covered.
• Pilots expected an increase of pilot workload in free flight. The evaluation caused a slight shift in
the positive direction.This increase of workload is due to adding an extra task to the pilot, separation assurance.
However pilots also indicated that the communication task with ATC will disappear which is
especially within Europe sometimes a demanding task. The opinion that free flight will increasepilot workload demands a clear, easy to understand and easy to use interface for the pilot.
• Lateral resolution manoeuvres are seen as more appropriate the vertical manoeuvres. Theevaluation did even strengthen this opinion.
In case vertical manoeuvres are preferred with respect to flight economics, this should be made
clear to the pilot, but more important is to make sure passenger comfort is not influenced. Theimpact of a vertical manoeuvre on passenger comfort should be investigated and not only in the
sense of changes in pitch and engine settings, but also secondary influences as for example cabin
pressure system activity.
• The look ahead time of 10 and 5 minutes for respectively managed mode and selected mode
operation are rated sufficiently long.The look ahead times seem appropriate for the time being. Data transfer times over ADS-B, on
board calculations systems and crew co-ordination process might require longer look ahead times,
but for current experimental setting the look ahead times are appropriate.
• Passenger comfort is not expected to be influenced by manoeuvres due to conflict resolutions.
(Assuming either horizontal manoeuvres or well predicted vertical manoeuvres).Assuming that the resolution manoeuvres calculated by the FMS are well calculated, unlike in the
evaluation in which manoeuvres were not optimised. For horizontal manoeuvres the opinions were
unanimous expressing that passengercomfort was not influenced, for vertical manoeuvres theopinions differed in the group of pilots. Again vertical manoeuvres will need more attention in their
effect on passenger comfort.
• Individual pilots have their own strategy and habits concerning display range setting during cruise
phase. Display range during a conflict needs attention.
Due to personal preferences of pilots it can be assumed that when a conflict occurs, the displayrange settings are non-optimal for giving a good overview of the situation. A solution might be to
automatically change the range setting in case the conflict occurs. This however is not compatible
with the way display control panels of current aircraft are used, namely with hardware rotary
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knobs with a pointer indicating the current range setting. Other solutions might be searched in the
direction of procedures, like in a similar event with TCAS in which the pilot first pushes the TCAS
button, which presents the TCAS display at the right range. Procedural solutions however are inthis stage of the system design not preferred.
• The FMS proposed resolution manoeuvre should be easy to understand and fit logically into theexisting flight plan in the eyes of the pilot. Presentation in the VSD is too complex and needs
further attention.
Pilots do review the proposed route in the sense whether it would be the route they might havechosen themselves. Routes containing a combination of horizontal and vertical movements are
never expected. For the conflict resolution module it is important to realise that complex and
economical best routes will put the pilot out of the loop possibly resulting in the case that a pilotignores the resolution route and will try to solve the conflict by means of a resolution manoeuvre
he defines himself. It needs no explanation that this will not serve the concept because a pilot will
certainly take an extra safety margin which decrease the flight efficiency.
• The required pilot action in case of a conflict were clear but alerting the pilot about the existence
of a conflict should be done after the priority has been determined.During the evaluation no alerting was available. Most pilots indicated that a kind of an attention
getter is required. A combination of a visual and aural alert is proposed. Visual in the sense of
presentation on the display but also a warning light on the glareshield. The right aural alert willneed attention because the amount of already existing aural signals is rather high.
• Traffic should not be presented in the VSD in the normal situation. Only in case of a conflict theVSD should present this. This will also make the VSD easier to interpret and allow easier
correlation with the HSD.
The VSD should be kept very basic, only the essential information should be presented in order tohave a positive impact on the situation awareness of the pilot. Presenting traffic in the normal
situation does not prove to add anything for the pilot, so during the normal situation traffic should
not be presented probably. In case of a conflict, the traffic should be presented or at least theprotected zone of the intruder. This in combination with the resolution manoeuvre or resolution
advisory in case of selected mode operation does provide useful information. However, some pilots
even indicated that the VSD can be removed at all. The HSD with traffic and altitude of trafficgiven in the labels gives a sufficient overview of the situation. It proves to give even sufficient
information to initiate a vertical manoeuvre. Most vertical manoeuvres were initiated in the runs in
which no VSD was presented at all.Adding a vertical speed scale in the VSD is useful for estimating the characteristics of the vertical
manoeuvre.
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A clear answer to the question whether the time scale or the distance scale should be used is
difficult. Both have their advantages and disadvantages and the opinion over the group of pilots
was divided depending on the priority given to the respective advantages and disadvantages. Thetime scale has the advantage of giving directly the amount of time before the conflict occurs and
when and how the resolution manoeuvres will solve it. The relation with the HSD however is
difficult. For the distance axis applies that it provides redundant information with the HSDallowing for an easy correlation with the HSD but at the same time it is not providing a lot more
information about the conflict.
Recommendation taken from the evaluation however is to investigate a VSD with a time axis alongthe route presenting only the protected zone of the intruder. In this way the VSD is expected to be
sufficiently simplified and adds to the situation awareness during a conflict situation.
• Only one resolution manoeuvre should be presented to the pilot. A second, or more, manoeuvre
should be available for the pilot, but this may require extra selections from the pilot.
In the normal situation the FMS should provide the solution which can directly be used by the pilot.In those cases that the pilot has more background information about the situation a secondary
solution should be available.
Activating the standard solution must be easier than the current required CDU actions. A possiblesolution might be provide a new function on the auto pilot panel which would behave like an auto
pilot intervention on the FMS. In this situation one remains to fly FMS coupled, but an action on
the auto pilot panel modifies the FMS route. This would avoid pilots to force to take action headdown on the CDU.
• Managed mode operation is preferred by most pilots although it places the pilot more out of theloop than selected mode operation.
The advantages and disadvantages of both managed mode and selected mode operation was
recognised by all pilots. The majority of the pilots indicated a preference for managed modeoperation due to the expected lower workload. Selected mode operation puts the pilot really in the
loop, but being an active part of a control loop means also that it takes more effort to complete this
task.In addition a number of pilots indicated that the combination of the two, managed mode and
selected mode, would probably be a requirement. There are situations in which one deviates from
the FMS route, for example due to weather indicated by the weather radar. Using heading select isfar more easier than changing the FMS route (assuming current flight deck implementation).
During this phase of flight when one diverts from the FMS route the selected mode might be used
until the FMS route intercepted again, or the FMS route has been changed and activated again.Not being able to change the route at all is not acceptable. It should be able either to fly standard
auto pilot modes or to modify the FMS route in an similarly easy way.
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• Windows are useful for important information and should easily be selectable and removable.
Windows on the navigation display are consuming display space in the primary field of view of the
pilot. They also hide navigational information. So, windows should only be used for informationwhich is highly relevant for the task the pilot is performing. Presenting background information
about the system should for this reason not be presented on the navigation display, but an other
location on the flight deck should be found.
• Presentation of the intruders' route is useful in order to be aware of the conflict characteristics.
In case of a conflict the route of the intruder should be presented because only then it is possiblefor the pilot to understand why the situation is a conflict. It also is an aid to pilot to understand the
FMS proposed resolution manoeuvre in case the own ship has to take action.
• Pilots want to be aware of a conflict situation even when the intruder has to take action.
Even in case the own ship has priority the pilot wants to be alerted about the fact that a conflict
situation occurs. It might however be alerted in a later stage then the situation in which the ownship has to take action. The time limit of starting the contingency manoeuvre was found too late
because this leaves the pilot only a short time to understand what is going on and which action to
take.
Recommendations.• Traffic should not be presented in the VSD.• Only the protected zone of the intruder should be presented in the VSD, not the intruder aircraft
itself.
• Altitude and V/S target values should be indicated on the VSD in order to present a verticalresolution more clearly. This applies mainly for selected mode operations.
• The horizontal axis of the VSD should be mapped along the route as long as managed mode is
operated, in selected mode this axis should be mapped along the heading axis.• The horizontal axis should represent time.
• A V/S scale should be part of the VSD.
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Annex C. Detailed results of EMERALD project
Here follow some extracts from EMERALD documents.
C.1 List and Classification of Potential ASAS applications
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Classification of the ASAS applications
ASAS applications may be classified into three different classes:
EMERALD main assumption is that the requirements of each class include those of the previous class.
This method gives three equipment classes, each being roughly more complex and potentially having alater applicability date than the previous.
• Traffic Situation Awareness applications
This is the first stage on the way to more complex ASAS applications. These applications will
provide the pilot with data on his environment (traffic, airspace,...). A Cockpit Display of TrafficInformation (CDTI) will be used for such applications.
An increase in traffic situation awareness may occur even when the percentage of ASAS equipped
aircraft is small. The benefits to equipped aircraft increase as other aircraft equip, and full trafficsituation awareness is achieved.
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Other Traffic Situation Awareness applications could be envisaged (weather reporting, airport
information,...) but are out of the scope of EMERALD.
No responsibility delegation is required for this class.
• Tactical Co-operative applications
These applications will help to manage the relative movement between two aircraft while they are
in close proximity to each other.
They can be divided into two sub-classes:Ø Distancing applications: in these applications the two aircraft are close to each other only for a
very short duration.
Ø Shadowing applications: in these applications, the two aircraft are required to stay at the samedistance for some time.
Moreover, the aircraft could be either automatically guided by the TC application or not. An
example of the former is the ASAS Crossing Procedure (ACP), and an example of the latter is theClosely Spaced Parallel Approach (CSPA) application in IMC, both applications having been
studied in WP5.2.
The pilot will receive full responsibility delegation from the controller for the duration of theapplication and for the specific purpose of separation with the aircraft involved in the application.
This is because applications envisage that the pilot will use ASAS to maintain separation from
specified aircraft and controllers cannot be responsible for the pilots actions, even though thecontroller might retain some responsibility for monitoring the maintenance of the required
separation (personally or automatically).
• Strategic Co-operative applications
These applications will help the pilot to manage his own route, in agreement with other aircraft andATC, over a long time horizon. Unlike the TC applications, more than two aircraft can be involved
simultaneously in SC applications. The Autonomous Aircraft (AA) application, studied in detail by
EMERALD, is one of them.The aircraft will be guided automatically by the SC application, checked by the pilot.
The pilot will receive full separation responsibility for the time he flies in the airspace reserved to
the SC application.This application may support progress to Free Flight but cannot by itself enable Free Flight. ‘Co-
operative ATC’ is still needed for this application.
It would at first appear that TSA is the least demanding class of application and SC the mostdemanding. However, some TC applications may be implemented in high density airspace leading
to a longer pre-implementation phase than is currently envisaged for SC applications. Indeed, the
high traffic density implies reduced aircraft manoeuvrability and increased pilot workload, and also
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may include the approach phase of flight. This may result in greater complexity of operation than
for SC applications.
C.2 Requirements for Decision Support Tools
Pilot’s interface
• Some general considerations common to the three applications were identified:
Ø Human factors aspects- There is a need of inter-crew communications to create a party-line effect. This specific ASAS
crew workload is a function of the number of surrounding aircraft and obviously is increasing
with the number of aircraft.- Speed manoeuvres take effect on a long term time horizon and discourage the crew to use
speed resolution for tactical conflict resolution
- The influence of airlines competition on the pilot’s behaviour in self-separation situation has tobe taken into account in the ASAS flight rules definition.
Ø Display format- Heading changes are easier to evaluate on a 2D display.
- There is a need of a 3D display for evaluation of a vertical escape manoeuvre related to altitude
change and, to a less extent, speed change.- A maximum display range of 160NM is required in low traffic density areas and for a weather
situation display.
- There is a need of continuity between the ASAS symbology conflict detection and the TCASone.
- There is a need to display the traffic situation X minutes in the future, through a pseudo-speed
vector (relative or absolute) where the head of the arrow represents the estimated aircraftposition (relative or absolute) in Xmn. It needs to know the aircraft speed and track but also its
turn rate and its speed change. Another approach is to display the trajectories and the potential
conflicts indicated as «no-go» zones.- There is a need to prioritise the detected conflicts as a function of their time horizon.
Ø Displayed Data- Data to be displayed have to be time-coherent at less than 1 second and not older than 5
seconds to allow a good pilot situation awareness.
- There is a need of graphical display of separation advisories such as:
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§ for short term issues, manoeuvres like:
- required heading change and maximum turn rate;
- required vertical speed and maximum vertical speed;- required speed change, speed envelope and maximum acceleration/deceleration rate.
§ for long term issues, airspace volume reserved for separation manoeuvre like:
- offset window;- altitude window, and maximum altitude;
- longitudinal separation distance window.
- the complete optimised trajectory taking into account the preceding constraints.
• Requirements for Longitudinal Station Keeping application:
A CDTI display will be necessary i.e. a display enabling the pilot to see the surrounding aircraft, to
select one/several aircraft and to get flight information about these aircraft.
The relative distance and the relative speed with the preceding aircraft has to be materialised on thedisplay.
Visual aids could be useful to indicate:
- the preceding aircraft capture procedure (speed, acceleration/deceleration rate), based onaircraft performance),
- the preceding aircraft speed following procedure: maintain Xnm +/- ?nm between two aircraft,
with X= 7nm +/- 0,5nm for instance.- the preceding aircraft speed change following procedure: need of co-ordination between the
two aircraft.
- the standby or recapture procedure after the preceding aircraft has left the stream.The following skeleton display illustrates the preceding specific LSK display requirements where
the Aircraft has to follow an aircraft at a distance of 20 Nm in 10 mn. Its target speed and its target
track are supposed to be computed by the ASAS application and followed either by the pilot or theautopilot.
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• Requirements for Closely Spaced Parallel Approach application:
It is required to avoid unexpected alarms of TCAS in TMA.As far as the pilot is responsible of the airborne safety monitoring based on the ASAS display
during an hazardous application, strong attention has to be given on this specific human-machine
interface to avoid any airborne situation misunderstanding. The approach phase is a head-up flightphase. There is a requirement to present traffic, conflict alarms and separation manoeuvre orders on
a head-up display. This has to be further analysed to take into account all the head-up requirements
and to see their compatibility with existing Head Up Display (HUD). Only a small part of theworldwide commercial aircraft fleet is equipped with HUD. From an economical point of view, it
would be difficult to justify the HUD retrofit only for an ASAS purpose on an aircraft not HUD
equipped.
A CDTI display will be necessary i.e. a display enabling the pilot to see the surrounding aircraft, to
select one/several aircraft and to get flight information about these aircraft.The CDTI should display a Non-Transgression Zone (NTZ) between the runways to help the pilot
to avoid endangering the other aircraft. The approach axis should also be materialised in order to
help the pilot to assess his position. In addition the display’s scale and definition should be adaptedto the visualisation of a small area.
There is an issue to be raised on the NTZ. This zone is defined for the air traffic controller display.
For the pilot display we have three different zones which can be displayed:Ø the basic ASAS protection zone which is a circle around the aircraft.
Ø the NTZ which is like a wall between the two runway axes.
Ø the tunnels delimiting the allowed airspace for approach and landing around the two runwayaxes.
A geometric synthesis of these three volumes is required for a pertinent picture for the pilot.
The relative distance with the preceding aircraft has to be materialised on the display.The following skeleton display illustrates the preceding specific CSP display requirements:
• Requirements for Autonomous Aircraft application:
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A CDTI display will be necessary for enabling the pilot to see the aircraft and the surrounding
aircraft positions or relative positions, to select one/several aircraft and to get flight and flight planinformation about these aircraft.
From a high level point of view, Autonomous Aircraft operations cover ASAS Crossing Procedure(ACP) and In Trail Climb/Descent (ITC/ITD) equivalent procedures in free flight airspace. These
procedures can be different from the basic ones. The Autonomous Aircraft display requirements are
the synthesis of the display requirements for these procedures.
Data to be potentially displayed are a priori the following ones, for each selected aircraft:
- flight identifier;- relative altitude;
- relative bearing;
- relative range;- closure rate;
- ground speed;
- ground track indication;- potential conflict status, if required
- conflict resolution assistance data
The following skeleton display illustrates the preceding specific AA display requirements in thecase of a crossing procedure.
The head of the arrows represent the aircraft position 3mn in the future. The conflicting aircraft is
on the left and flying at 490kts. It should be indicated in red. The proposed deconflicting trajectoryis on the left on the active trajectory and should be indicated in green.
Controller’s interface
• General requirements:
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All ASAS applications involving a dialogue between the pilot and the controller, the lattershould have a means of knowing which aircraft are ASAS equipped and possibly withwhich ASAS application. This could be done for example through the paper strip or as aspecific marker on a high resolution control screen.Furthermore, nearly all ASAS application will require that the controller maintain a monitoring
function, so as to regain control in case of emergency. To that end, it might be necessary to adaptor to augment current control tools.
• Requirements for Longitudinal Station Keeping application:
It is likely that new controller assistance tools will be required to help him safely monitor the
established stream whilst treating a stream of aircraft as a single entity. If the controller establishesa stream at a certain flight level, and gives the lead aircraft a specific speed to follow, then the
stream will have a common flight level and speed. As the stream achieves a generic flight profile
the controller may lose his full situational awareness of the trajectory of an individual aircraft. Thereal or perceived situational awareness may be further reduced by the pilot’s ability/permission to
operate in a ‘bubble of uncertainty’.
When the stream is being established, or a single aircraft is joining the stream, the controller mayneed specific information about the aircraft approaching the stream. It may be necessary to predict
when an individual aircraft will reach the stream so that the controller directs the aircraft with
minimum disruption to the rest of the stream. This function may be similar to the arrivalsequencing of aircraft into a final approach.
However, further work may be required to determine the accuracy of the information required, as
well as what information is required.As the controller retains the responsibility of separation between aircraft, one function of the ATC
system may be to show the controller the conformance of the aircraft trajectory within the
constraints of the stream. The system task will be to monitor the aircraft within the stream, and tocontrol the stream. The data that will be required by the ATC system is:
Ø Proposed separation from parallel/lateral tracks
Ø Area of airspace designated for station keepingØ How many aircraft are in the stream (e.g. by marking the lead and end aircraft so that the
boundaries of the stream are unambiguous). This data is particularly relevant during the
handover of a stream to another sector.Ø Places where aircraft may enter or leave an already established stream. This may be a way
point or junction en route.
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The controller display may be required to show:
Ø Conformance of lead aircraft with intended trajectory.
Ø The ATC system (i.e. the controller) may need to mark the lead aircraft position and the endaircraft position in order to define the boundaries of the stream being controlled.
Ø The display will need to show the separation that has been set.
Ø Separation monitoring alerts.Ø Aircraft intentionally breaking away from station keeping due to emergency etc.
• Requirements for Closely Spaced Parallel Approach application:
The controller will have a means to know which aircraft is capable of performing CSPA, via the
strip for example, or by radio (voice or ground-air data-link).Due to current approach radar precision, the controller might be unable to distinguish a blunder
trajectory on time to act efficiently. As this feature is judged unacceptable, controllers need to be
provided with more precise and more frequently updated data.For example, with ADS-B data, ATC would monitor the ADS-B messages ensuring that an aircraft
maintains conformance to its intended trajectory. The integrity of ADS-B data would be checked
on-board. It could also be done via a more sophisticated approach radar.The controller may require a separation monitoring tool. The controller, due to workload, is
interested in the ‘big picture’. As ADS-B information is also available on the ground, a separation
monitoring function (either automated or ATC selectable) may be used.Although, for the time of the CSPA, legal responsibility for staggered separation has been
delegated to the pilot, the controller must be able to recover the situation in case of CSPA capacity
loss. Consequently, it might be judged necessary to help him with a recovering tool.Immediately available communication between pilots and controllers is of crucial importance in the
safe conduct of simultaneous parallel ILS approaches.
• Requirements for Autonomous Aircraft application:
In the autonomous mode, the responsibility for safe separation belongs to the pilot. However, thecontroller is required to limit the number of aircraft in the FFAS, and control aircraft as they enter
and exit. In addition, in the interests of safety, the controller should act in a monitoring role the
information is available. This will require the following information to be available:Ø Separation and conflict monitoring (where available).
As aircraft separations reduce, the controller can monitor any change of trajectories and check
that minima are not breached. This would require software tools optimised to show theintentions of the aircraft and automated warnings to predict when limits would be exceeded.
Ø Aircraft intentions.
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The controller monitors the aircraft's intentions, to check its exit time and position and monitors
expected traffic density.
Ø Number of aircraft in area.In order to manage the flow of aircraft from ‘Gate to Gate’ and encompass in a more global way
the transitions from TMA through Managed Airspace into Free Flight Airspace and back, the
controller must monitor the density of aircraft either for the entire route or for sub zones, andauthorise according to the traffic density expected during the passage of the aircraft. This phase
would be a refinement of the planning phase, where the Airline Operations Centres (AOC)
would allocate the flight profile in advance. The profile may be reviewed just before take off totake into account dynamic information such as weather.
This would require Airlines Operation Centres to be interconnected to the Air Traffic Services
(Control Centres or Central Flow Management Units) for two reasons:- To provide the detailed flight profiles, which have been, loaded into aircraft FMS to the
ATS. Another scenario would be to consider that each aircraft, which plans to perform AA
operation, must transmit to the ATC its long-term intents. In that case, the most likelysolution would be to use addressed data-link between the Aircraft and the controller.
- To have access, under ATC control, to the long-term view of the traffic that its AA may
have to face.
C.3 Operational Procedures
• Longitudinal Station Keeping application
There are several aspects of operation for the station keeping application, which require distinct
procedures.
1. The first of these is joining or establishing the stream. The initial join of the 'slave' aircraft tothe 'master' aircraft may be difficult. ATS must be aware of the 'master' aircraft's intentions in
order to allow the 'slave' to be easily guided into position.
2. The second of these is maintaining separation. Separation is maintained by the slave aircraftand separation is followed within a ‘bubble of uncertainty’ for each aircraft where each aircraft
can vary their separation from the aircraft in front within certain tolerance. Speed control is
imposed on the lead aircraft and advised to the succeeding aircraft in the stream. A controllerassistance conformance monitor may alert the controller to any deviation from the required
flight profile within the stream.
3. The third of these is leaving the stream or disestablishing the stream. The controller breaks thepairing within the stream and new pairing is established across the ‘gap’ left by the departing
aircraft. It is unlikely that the remaining aircraft would close the gap.
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Instead, a new separation would be established between the new pairing which is
approximately twice the value of the original pairing. This prevents undue stress on the
performance of the slave aircraft (as well as the following pairs of aircraft), in a ‘catch up’manoeuvre.
4. The fourth of these is the task of handing over a stream to another sector. Complete details of
the stream is communicated between the sectors during the handover.5. Another aspect of station keeping is the emergency procedures that may be required during any
time in the station keeping application. In an emergency either an emergency descent or a
lateral manoeuvre to a ‘hard shoulder’ would be required. The lateral manoeuvre may conflictwith closely spaced parallel routes, and this manœuvre requires further consideration. Current
en route lateral separation standards require 10 NM separation. As with the ‘leaving the stream’
the remaining aircraft in the stream will maintain a new pairing across the ‘gap’.
Ø Actions and responsibilities taken by the pilot and the controller
Controller
- Decides which aircraft are suitable for station keeping,
- Issues instructions to the aircraft to assume responsibility for station keeping,- Gives desired spacing interval from preceding aircraft, and its callsign, heading, distance,
and altitude to the following aircraft.
Pilot
- Accepts station keeping option.
- Must correctly identify the preceding aircraft and maintain the self-spacing function.
Ø Proposed actual separation between aircraft to be applied by the pilot during the procedure.
Close to radar separation. This could be greater depending on the demand for airspace i.e. in
low capacity traffic the required separation could be greater than the standard requirement.
Ø Proposed new, or new usage of current, radiotelephony (R/T) phraseology
- Acceptance/ Rejection of station keeping option.- Confirm correct acquisition of preceding aircraft, and required spacing.
- May use data link to issue some of the instructions (CDPLC).
- R/T or data link information between a controller and a specific aircraft may be required byall other aircraft in the stream to maintain situational awareness about new instructions to
the specific aircraft concerned.
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Ø Limiting factors which could affect the application of the procedure
- Pilots unable to maintain separation, or unhappy with maintaining minimum separation.
- Poor mix of aircraft types not suitable for station keeping.
Ø Controller’s responsibility to maintain a monitoring function;
Controller will set up and maintain current monitoring function at a lower level of workload.
Ø Proposed contingency procedures.
If either the controller or the pilot are not satisfied with the separation from the preceding
aircraft then a break manoeuvre must be initiated. The passing manoeuvre would be preferablewith the 'slave' aircraft changing altitude or track.
Ø Questions to Answer
Would it be feasible for aircraft to form pairs without controller intervention. This would
significantly change the ‘Joining Procedure’, and would reduce controller workload, but wouldalso mean that a greater transfer of data would be required between the aircraft concerned e.g.
flight plan data.
It is likely that a ‘bubble of uncertainty’ would be required for each aircraft in the stream.More work is required to establish whether a small or large tolerance is operationally preferable,
and also whether this tolerance varies depending on the aircraft position in the stream e.g. the
last aircraft following a stream may require a larger tolerance to minimise consequences of allthe other aircraft varying their relative positions to one another.
• Closely Spaced Parallel Approach application
Ø Actions and responsibilities taken by the pilot and the controller
During simultaneous parallel approaches aircraft are directed to the final approach courses at
different altitudes separated by at least 1000 ft. This separation is necessary because the
normally maintained 3 NM separation is lost as the aircraft fly toward their respective localisers.Once the aircraft are established on the parallel localiser course, the 1000 ft vertical separation
is no longer maintained, and they are permitted to descend on the glideslope, flying toward the
airport separated by the distance between the runways centre lines.One monitor controller observe and monitors the final approach course, runway complex, and
portions of the departure fan for the runways. The parallel runway approaches are divided into
multiple zones. the No Transgression Zone (NTZ) is an area in which aircraft are prohibited to
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enter. It is established equidistant between the extended runways centrelines. If an aircraft
blunders from the Normal Operating Zone (NOZ) into the NTZ, any endangered aircraft are
turned away to prevent a collision.
The CSPA will enable the pilot to be delegated the following function:
- provide CSPA separation between succeeding arriving aircraft;
This delegation will apply only on the basis of an agreement between the pilot and the
controller, either on a case by case basis, or on a more formal and general basis (agreementprotocol between involved parties). Within this condition, the actions and legal responsibilities
are the following:
Controller
- lines up the aircraft in the staggered approach pattern (if necessary, with the aid of tools)
- communicates identity and separation required to pilots- monitors situation in respect of separation ‘busts’.
Pilot- maintains and monitors separation from preceding aircraft using a CDTI. The legal
responsibility for separation starts from the time the CSPA clearance is given until the
time the aircraft he separates from touches the runway or initiates a breakout manoeuvre
Ø Proposed separation between aircraft to be applied by the pilot during the procedure:
Minimum separation recommended by ICAO.
Ø Proposed new, or new usage of current, radiotelephony phraseology:
- phraseology to give and confirm ident of preceding aircraft on pilots’ CDTI- phraseology to give and confirm required separation.
- phraseology to allow pilot to action go-around on separation ‘bust’.
Ø Limiting factors which could affect the application of the procedure:
Not all aircraft on approach have functional ADS-B/ASAS equipment.
Ø Controller’s responsibility to maintain a monitoring function
The controller (using a separation monitoring tool, if necessary) may demand a go-around. The
legal responsibility of staggered separation has been devolved to the pilot, but the controller hasright of veto.
Ø Proposed contingency procedures
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Go-arounds on separation infringements, the same as for VFR conditions (to be more closely
studied).
• Autonomous Aircraft application
Ø Actions and responsibilities taken by the pilot and the controller
Pilot- checks ADS-B equipment in operation (Display with OK status of AA application and
ADS-B subsystem).
- requests entry into free-flight area.- transmits Identification (call sign, address and category), position, Navigation Uncertainty
Category and its expected trajectory to the controller, using long distance data-link
communication Medium.- deconflicts with aircraft in free flight airspace.
- requests exit from free flight airspace.
Controller
- clears aircraft into free flight area and AA operations.
- provides the aircraft with long term traffic prediction and AA clearance to the aircraft for apre-determined airspace. The controller is assumed to use long-distance data-link
communication medium.
- clears aircraft into non-free flight area and normal operations.
Ø Proposed separation between aircraft to be applied by the pilot during the procedure
The concept is still in its infancy and requires some work to determine the precise
characteristics. The use of existing or future GNSS provides very accurate time stamped
positions providing a great potential for reductions in separation, particularly in areas of existingpoor radar coverage. However, it may be the accuracy of prediction of the other aircraft
trajectories, and allowance for time to manoeuvre that may be the critical factor.
Ø Proposed new, or new usage of current, radiotelephony phraseology;
Whilst in autonomous operation the aircraft does not require any communication with ATC.However, during the entry and exit from the Free Flight area some additional communications
will be required. Given that the concept represents a highly integrated system, it would be
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expected that all routine communications would be performed over the data-link. However, this
does not exclude the possibility of using standard R/T techniques as a backup.
The following communication protocols would be required;- Acceptance / rejection of entering free flight area.
- Acceptance / rejection of entering autonomous operation.
Ø Limiting factors which could affect the application of the procedure;
The possibility of localised points of high density within the free flight airspace may cause largenumbers of aircraft to deconflict. The conflict may be a long term one, caused by the crossing of
preferred routes or short term caused by the aircraft changing track to avoid bad weather.
Ø Controller’s responsibility to maintain a monitoring function;
Although the tactical decision making process has been devolved to the pilot, the controller willmaintain a monitoring function in a more strategic sense.
Ø Proposed contingency procedures.
In circumstances where equipment fails, the aircraft may be required to cease operating
autonomously and / or change flight level to non-optimum altitudes, which are controlledprocedurally and are not part of the FFAS. During such a transition, the ACAS would be used as
a final safety net. It is important to note that the use of ACAS should not be reflected in any
level of safety assigned to this concept, but only used should the other contingency proceduresfail, as is the case with other ATM concepts
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Annex D. CENA
ADSP and SICASP classification of ASAS of applications as proposed in [6, 12]:
ADSP and SICASP recognise two broad classes of ASAS applications:
1. Traffic situational awareness applications : “The provision of information to the flight crew toconvey the position and other information such as the identity, status and the intentions of the
other aircraft with respect to their trajectory”.
2. Co-operative separation applications: “Applications comprising sets of actions, automatic or
manual, each of which have a clearly defined operational goal, and begin and end with an
operational event, during which time the pilot uses ASAS equipment to comply with a clearancethat preserves ASAS separation between his aircraft and certain other aircraft”
• Traffic Situational Awareness applications can be defined within the scope of existing ATCpractices. These applications are considered to be the first stage in the development of more
complex ASAS applications.
• By taking advantage of the new sharing of information between the ground and the airborne side,
together with the provision of airborne separation capabilities, the co-operative Separation
applications envisage the transfer of some separation assurance tasks to the aircrew within newATC procedures. This is the innovative part of the ASAS concept.
Traffic Situational Awareness applications
Increased aircrews’ traffic situational awareness is seen as a mean to improve safety in the current
ATC system. It will also enable more efficient visual procedures. This was not possible in the past dueto the lack of a cost/efficient technology.
The provision of traffic situational awareness does not constitute separation assurance in itself. Nodelegation of separation responsibility from the ground to the airborne side is envisaged for Traffic
Situational Awareness applications.
Possible Traffic Situational Awareness applications are the following ones:
1. Improved aircrew mental picture with respect to the surrounding traffic. In the current ATC
system, this could ease the aircrew understanding of the ATC instructions. In the future ATCsystem where digital data-links will be implemented, Traffic Situational Awareness applications
could be required to compensate, for example, the loss of party line;
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2. Improved ‘see and avoid’ principle, in particular for the compatibility between IFR and VFR
flights. Indeed, we have reached the limits of this principle because of the increasing speed of
aircraft, the poor external visibility in modern cockpits and pilots’ workload in some phases offlight;
3. Improved current visual procedures, like in visual approaches where the pilots can be instructed to
maintain visual separation with the preceding aircraft; and4. Enhanced ‘Traffic Information Broadcast by Aircraft’ (TIBA) procedure. In addition to
broadcasting periodic position reports on VHF, the pilot could identify the surrounding traffic with
his ASAS system and speak directly to the other aircraft which might interfere with his trajectory.
• An increase in traffic situational awareness may occur even when the percentage of suitably
equipped aircraft is small. Nevertheless, partial equipage will limit the utility of such ASASapplications.
• There will be training issues to prevent incorrect use of Traffic Situational Awareness• applications such as inadequate questioning, or unexpected manoeuvres, which could be
disruptive to ATC.
Co-operative Separation applications• In the current ATS system, air traffic controllers are in charge of preventing collisions and
maintaining an orderly and expeditious flow of traffic. The separation is a mean to achieve safeand efficient aircraft operations within en-route airspace, terminal area and at airports.
• Pilots are in charge of the safe and efficient control and navigation of their individual aircraft.
Unlike air traffic controllers, pilots currently have no separation to maintain between aircraft,other than to avoid collision and wake turbulence.
• The delegation of separation assurance from the ground to the airborne side is seen as a mean to
improve flexibility and capacity of the ATS system. Under specified circumstances, the aircrew,when provided with the adequate tools and procedures, could be in position to maintain airborne
separation from other traffic.
• The purpose is to alleviate air traffic control constraints by involving more the aircrew in theseparation assurance process, and thus, enabling more flexible and efficient aircraft operations,
while preserving or enhancing safety.
• The main expected benefits are increased ATC capacity through both the reduction ofcontroller’s workload and, if possible, the reduction of separation minima. Furthermore, there
should be better conformance to separation minima.
Possible Co-operative Separation applications are the following ones:
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5. Station keeping applications where the following aircraft is cleared to maintain an airborne
separation from a leading aircraft. This could be applied on oceanic routes, in en-route airspace or
in approach airspace;
6. Crossing applications where, after the conflict is detected by the controller, the pilot is instructed
to maintain airborne separation minima from the other aircraft. Horizontal or vertical passingmanoeuvres are similar applications; and
7. Own separation applications where, after the controller has checked that the traffic to beencountered is suitably equipped, the pilot is cleared to maintain airborne separation minima with
that traffic within the boundaries defined by the clearance.
• It is anticipated that explicit co-ordination will be an essential part of many co-operative
Separation applications. This co-ordination could be provided by ATC, but an air-air
data-link is expected to support, in many cases, the necessary co-ordination for separation assurancemanoeuvres.
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Safety analysis work
The following tables presents the operational hazard analysis (OHA), the hazard likelihood analysis
and the allocation of safety objectives and requirements (ASOR) issued from the paper [5]
Table 1: OHA table for ASAS applications
Operational Hazard Effect on ASAS
operations
Severity Mitigating Factors
Infrastructure / systems
Procedures / operating practices
ASAS Crossing
Procedure
Incorrect identification
of target aircraft at the
procedure
initialisation
Potential loss of
separation since the pilot
(of own aircraft) may
accept the ASAS
procedure with respect to
a wrong aircraft (in close
proximity) and not
execute the required
separation manoeuvre
with respect to the correct
target aircraft
Major A) CDTI features enhance pilot’s situational
awareness about surrounding traffic
Traffic advisory provided by ACAS/TCAS as
conflict increases between own and correct
target aircraft
If airborne and ground separation minimum are
compatible, Short Term Conflict Alert raised to
ATC between aircraft involved in the procedure
B) Procedural requirement for the pilot to report
any change in altitude, direction or speed during
the procedure
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Hazard Incorrect identification of target aircraft at the ASAS procedure initialisation
Possible
causes
Corrupted
ADS
identification
report by other
aircraft
Corrupted
track
correlation by
own airborne
surveillance
Corrupted
aircraft
identification
displayed in
the cockpit of
own aircraft
Air traffic
controller
identification
error when
initialising the
ASAS
procedure
Pilot (from
other aircraft)
error when
entering a/c
identification
transmitted
through ADS
Pilot error
when
identifying
target aircraft
on the CDTI
Likelihood
of
occurrences
Avoiding
Factors
A) infra-
structure /
systems
B)
Procedures /
operating
practices
A) Integrity
requirement
for ADS
report (RCP),
and
Consistency
check of ADS
identification
report by the
ground
surveillance
system (either
manually or
automatically)
A) Integrity
requirement
for airborne
surveillance
(RSP)
B) Procedural
requirement
for the use of
target
identification
in conjunction
with traffic
information
for
consistency
check by the
pilot
A) Integrity
requirements
for cockpit
display
B) Procedural
requirement
for the use of
target
identification
in conjunction
with a traffic
information
for
consistency
check by the
pilot
B) Procedural
requirement
for the use of
target
identification
in conjunction
with traffic
information
for
consistency
check by the
pilot
A)
Consistency
check of ADS
identification
report by the
ground
surveillance
system (either
manually or
automatically)
B) Cross
check
procedure
within cockpit
A) Ease of use
of CDTI and
highlighting of
aircraft
identification
of selected
target
B) Cross-
check
procedure
within the
cockpit
Table 2: Hazard likelihood analysis for ASAS applications
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Hazard Description Consequences Avoidance Factors
A) Infrastructure /
systems
B) Procedures /
operating practices
Mitigating Factors
A) Infrastructure /
systems
B) Procedures /
operating system
ASAS Crossing
Procedure
Incorrect identification of
target aircraft at the
procedure initialisation
Potential loss of separation
since the pilot may accept
the ASAS procedure with
respect to a wrong a/c
See Figure 3 See Figure 2
Enhanced Visual
Approach
Pilot misjudges in-trail
spacing or closing speed
Loss of separation A) CDTI features
displaying range and
closing speed
B) Pilot training and
procedures
A) ASAS alert to pilot
B) ATC monitors spacing
and may issue warning
Conflict detection &
Resolution
Pilot receives incompatible
instructions from
controller and from ASAS
Pilot unable to comply
with both. Potential loss of
separation with original
threat or with other
B) Procedures must
govern the responsibility
for resolving conflict
B) Procedures must
resolve this situation
Pilot receives
simultaneous ASAS
resolution and ACAS
Resolution Advisory (RA)
Pilot may be unable to
comply with both.
Potential loss of separation
A) ASAS design should
ensure issuing its conflict
resolution prior to ACAS
RA, and should defer to
ACAS when it generates
RA
A) ASAS must remove its
resolution or change to one
compatible with the RA.
B) Pilot training and
procedures establish
reliance on ACAS
Table 3: ASOR table for ASAS applications
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Annex E. FREER
FAST: force fields techniques adaptations
As presented in the section 2.1.3.2, the principle of the artificial force technique can be summarise as
follow: The aircraft moves in a field of artificial forces generated by the intruders, and by the flightplan. A force coming from an intruder represents a «by-pass» action; its direction is a separation
direction, and the magnitude is getting higher as soon as the aircraft is getting closer to the intruder.
The force coming from the flight plan represents an «attract» action.The resulting force is the sum of the above forces, which makes the aircraft:
1. follow its flight plan,
2. deviate smoothly when the risk of conflict increases, and then3. return progressively to the flight plan as soon as the risk decreases.
Slight adaptations of the algorithm presented in [6] are presented as follow.
Motion planning with this technique requires two steps:
• simulation of the movement of the aircraft in the field of forces, and then• processing of the traced plots (e.g. smoothing). In our case, this consists in extracting the
representative points (trajectory change points, or TCPs).
Assignment of Forces
Since the forbidden zones represent an anticipation of the situation, forces will be assigned to the
zones, not to the intruders.The resulting force for infringement avoidance can be defined as the sum of the forces of each zone.
However, to avoid unnecessary deviation with uncertain conflicting aircraft, it is possible to take
advantage of the uncertainty associated to a forbidden zone when getting closer.This principle is to «switch on» progressively the no-go zones as soon as the aircraft is getting closer
to a conflict zone. For this purpose, non-conflicting forces are pondered by a risk of conflict
represented by the magnitude of the conflicting forces.
Definition of Forces
In normal conditions, the force of a zone has to induce a by-pass movement of this zone. In case thezone is too close, i.e. emergency conditions, a go-away movement should be induced. Thus, for each
zone, the force is defined as a combination of:
• a sliding force defining the by-pass movement• a repulsive force defining the go-away movement
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FAST: Human-in-the-loop experiment
The following paragraph presents more detailed results obtained through the FAST experiment [7].
Autonomous operation tasks
– Generally, the CDTI significantly enhanced the overall situation awareness in the cockpit.
However, in case of abnormal situations, the information available about the other aircraft, inparticular whether its flight crew was aware of and able to solve the conflict, was found to be
insufficient (72% of the pilots requested to be alerted).
– When having the right of way, 78% of the pilots got worried as soon as the conflict zone poppedup, they did not know what to do.
– To compensate the lack of procedure for handling such cases, many pilots made up a time based
procedure, using the well accepted displayed tick marks (76% of the pilots) and includingcommunication with the other aircraft.
Such procedure can be typically defined as follows: In the 10 minutes look-ahead scenario, from
the conflict detection and up to 5 to 6 minutes before the conflict zone they had decided just tomonitor the situation. If after a few minutes the other aircraft had not manoeuvred they would
pretend to call him to know what was happening. If no answer was given within 1 minute by the
other aircraft they would start to manoeuvre even though they had the right of way. Some of themwere preparing themselves to modify it by displaying the no go zones through the solver
activation.
Conflict situation analysis
– The pilots found difficult to understand from which direction the conflicting aircraft was coming,
mainly because of the other aircraft tick marks.– In the case of “double conflicts”, they understood immediately through the interface that they were
in conflict simultaneously with two distinct aircraft: two yellow zones appeared. However, the
actual identification of the two aircraft causing the conflicts proved to be challenging, in particularif one had the right of way while the other was yielding: the colour coding of the aircraft appeared
inconsistent since one of the conflicting aircraft symbol was of the same colour as the own ship.
– 71% of the trial pilots easily identified the aircraft having to manoeuvre from its symbol colour, inparticular for the two aircraft conflicts.
– Priority rules were well accepted by the pilots. However some pilots underlined that since
descending aircraft have more flexibility in manoeuvring than climbing aircraft, they would havepreferred rules given priority to the climbing aircraft
Resolution:– If the pilot did not have to manoeuvre, he monitored the situation. This monitoring task induced a
high level of stress to the pilots as they are not used to passively monitor potential dangers.
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– If the pilot had to manoeuvre he had to solve the problem using either the manual solver or the
automatic solver or both.
– The pilot found the manual resolution very efficient. But 20% found it difficult to use mainlybecause the insertion logic was the one implemented on the FMS.
– The pointing device was very well accepted and seen as a very efficient tool.
– Pilot would like to have always access the manual mode to use it to avoid bad weather orrestricted airspace.
– Pilot expressed the need to have the automatic resolution mode.
– Pilot found the manual solution time consuming and workload increasing due to the insertion ofseveral way-points giving a refine solution.
– The automatic solution was seen very efficient but not adapted to all flight constraints (e.g. bad
weather conditions).– Time measurements showed that the manual resolution was more efficient as long as more than
three successive points had to be entered.
– Both resolution tools are required.
After the resolution
– 70% of the pilots requested to have means available to monitor the encountered aircraft until it haspassed the crossing of the tracks.
Interface:Displayed information
– Symbol and text labels are well understood.
– Size and resolution of displays are found adequate. The logic and colour scheme allowed the pilotsto quickly grasp the required conflict information without having to stare at the ND, hence
removing the impression of clutter. The
– The readability of the displayed information is found acceptable.– The pilot suggested to differentiate surrounding aircraft by three colours depending on their
altitude relative to own ship. A stricter adherence to colour scheme standards was strongly
recommended.– The colour changes when solving a conflict were found necessary and efficient.
– There was a tendency in the displays to have too much information, not always de-selectable.
– Some required information was missing since:– The detection of the prioritised aircraft was not performed correctly
– The logic of the manual way-point insertion was not corrected
– The EFIS pushbutton options were not standard.– Some information should be available on pilot demand.
– The own ship flight plan information should always be displayed and remain independent of the
display option activation.
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– In case of abnormal situation, 72% of the pilots requested a means to know whether the other
aircraft is going to manoeuvre or not.
– They suggested to be provided with an explicit priority reversal mechanism or to have the otheraircraft in conflict displayed just when an action was expected from the non manoeuvring aircraft.
Two of them relied on the TCAS as a back up.
– Pilots suggested that they would prefer to be alerted of the other pending trajectory modificationin order to increase safety and also to minimise deviations from original flight plan.
– They suggested that it would be useful display the trajectory of any displayed aircraft and its target
altitude as well as the numerical value of the separation.
Forbidden zones: conflict zone and no go zones
– Pilots mentioned that the transparency of the forbidden zones or the implementation of a priorityorder in the information could improve the conflict situation display.
– The display of conflict zones should be triggered both by a certain distance/time criteria and by
explicit pilot demand.– The pilots’ opinions on the presentation of the conflict zones were highly dependent on the
priority criteria: If the other aircraft had the right of way, the conflict zones were found to be
adequately displayed in the experiment set-up, but if the own aircraft had the right of way, theconflict zones were displayed using the no go zone colour coding, hence possibly misleading the
pilots on their nature.
– The pilots also mentioned that the CDTI should be an accurate and complete reflection of the ownship situation (All forbidden zones should be shown in case of conflict, and not only the conflict
zones).
– They also encountered difficulties in the understanding of the forbidden zones shapes. It was notobvious, for example, that the vertical dimension in the computation could result in the truncation
of the zones, despite the fact that the proposed resolutions is always lateral
– The display of no go zones should also be pilot selectable and not only be dependent on thedetection of a conflict .
– Pilots requested to be able to visualise, upon pilot request, the aircraft that create the no go zones.
– The forbidden zones were displayed graphically as “filled” objects. The pilots noted that in somecases it created too much clutter although it did not seem to have any impact on the efficiency of
the resolution. Using graphical transparency attributes for the zones is a potential way to address
this issue.
Automatic Resolution Interface
The following short comings of the solver have been identified:– The available solutions were only displayed on pilot demand.
– There was a lack of a priori check on the availability of a type of solution: directional arrows were
shown even if no solution in this direction existed.
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– In case where the own ship had the right of way, a SOLVE prompt was presented on the interface
instead of the right and left arrows. It was not obvious to all pilots that clicking on this prompt
would allow them to have access to the solver resolution (left and right arrows) and therefore tothe no go zones. The only zone shown was the conflict zone, displayed in such a case using no go
zone colour. Therefore some of the pilots thought there was no other forbidden zone.
– Switching between solver mode and manual mode was found to be cumbersome.
Responsibility / Workload
– Pilots readily concluded that the system would be valuable in low density areas. But even in high
en-route density areas, 46% of them thought that the system would help them to assure the
autonomous separation task.– Pilots were expecting to revert to ATC in abnormal cases (aircraft not manoeuvring as it should or
equipment failures cases. The pilots had no confidence in being able to conduct autonomous
operations with simply the given set of tools and no ground support.– When facing simple conflicts, 80% of the pilots were confident that the solver, with the manual
mode as a back up, was adequate to avoid conflict zones within the assigned time frame (at least 3
minutes before loss of separation) without ATC intervention.– The observed workload only reflects the one due to the conflict resolution task. The manual
resolution did not create the same amount of workload as the automatic resolution.
– A manual solution, with more than 2 inserted way-points is unacceptable in terms of workload– To reduce the amount of workload in all cases, a proposed solution was to display the automatic
solution by default at the conflict detection and allow to make manual modifications to it.
– Even if 80% of the pilots thought they could manage without ATC intervention, over 60% wouldhave preferred to have the ATC as a supervisor: the ATC role being to handle all abnormal cases.
– 40% of the pilots did not want to accept the responsibility of the autonomous separation assurance
task in any case. 20% accepted the responsibility but only in the case an automatic solution wasprovided
FAST: Extended Flight rules: Priority assignment
The following is an extract from [7].
The priority scheme used in the Extended Flight Rules (EFR), can be described as follow:
1) High priority is given to a descending aircraft,
2) Medium priority is given to an aircraft flying level,
3) Low priority is given to a climbing aircraft.4) In case of tie, the aircraft closest to the point of loss of separation has higher priority;
5) Should everything still be equal, the unique identifier of the communication equipment is used to
break the tie (e.g. lowest level o priority to first alpha numerical order)
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Conflict situation Description PriorityBoth in level * The closest to the point of loss of
separation
Both climbing * The closest to the point of loss ofseparation
Both descending * The closest to the point of loss ofseparation
A in level, B climbing A has the right of way
A in level, B descending B has the right of way
A climbing, B descending B has the right f way
Table 4: Extended Flight Rules Summary*: rule 5 may be applied on this case
EACAC: Procedure overview
The following is an extract of the document [12] which describes in detail the procedures for limited
delegations:
• Applicability conditions: Prior to delegating, the controller must make sure that all applicabilityconditions for the envisaged delegation are respected. The respect of these conditions guarantees
that the delegation is safe and beneficial. It should be noted that the higher the delegation level, the
more restrictive the applicability conditions are.• Delegation instruction : The delegation uses specific controller instructions to define the task
delegated, and pilot reports to mark phase changes and the end of delegation.
• Phraseology for delegation: All the communications between controller and pilot required by thedelegation use radio-telephony, i.e. voice communication. A new phraseology is proposed.
• Pilot agreement : The delegation requires the agreement of the pilot of the delegated aircraft. No
agreement is required from the pilot of the target aircraft, and no indication of his becoming atarget is given.
• Three phases: The delegation consists in three different phases:
1. Identification phase in which the controller indicates the target aircraft to the pilot of thedelegated aircraft.
2. Instruction of delegation in which the controller specifies the task delegated to the pilot.
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3. End of delegation which marks the completion of the task delegated.
• Interruption of delegation: The controller can interrupt a delegation at any time. The pilot can
interrupt a delegation in case of emergency only.• Transfer to next sector: A pair of target plus delegated aircraft can be transferred to the next sector
without needing to cancel the delegation.
• Additional instruction: During a delegation, the controller can give an additional instructionwithout cancelling the delegation if the instruction is compatible, i.e. if the flight parameter
modified by the instruction (e.g. heading) does not affect the parameter delegated (e.g. speed).
This is particularly envisaged for “direct-to” or “descent” for in-trail following.
The following tables summarise the different levels of delegation proposed for each application: En-
route (table 5 ), ETMA (table 6)
Airspace è En-route
Crossing and passingApplications è
Delegation level ê Lateral Vertical
Report Report clear of target Report clear of target
Resume then remain behind Resume then merge behind
Table 6: Sequencing applications.
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Phraseology examples:
Identification phraseology:The target aircraft is identified by the controller through its SSR code, which is an unambiguous
identifier. The identification consists in three messages: 1) the identification message in which the
controller indicates the identifier of the target aircraft. For cross-check purpose, the controller canposition the target or request the pilot to position it, 2) the pilot readback, 3) the pilot confirmation.
• Identification with positioning by the controller:– Controller: "DLH456, select target 1234, (3 o’clock / right to left / 30 Nm / 1000ft above)"
– Pilot: "Selecting target 1234, DLH456"
After pilot selection and identification on the CDTI:– Pilot: "Target 1234 identified, DLH456"
– Controller: “DLH456, end delegation, speed instruction”
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Annex F. NEAN-NEAP
The following conclusions have been brought by the trials:
MMI general impressions
The air crews have a positive impression of the MMI, and although there was a low rate of handlingthey already mentioned the following benefits for MMI:
- helps to orient in space
- backup for navigation- good charts
- good situation awareness
- precise navigation data- display of other traffic
- off track control.
The following comments were given in regards to the MMI:- idea of MMI welcome
- geographical charts good source of information
- GPS is a good back up- good if spread overall
- operation complicate
- keyboard required- distraction in flight
- visual channel overloaded
- database not complete (way points, airways)- display needs more contrast, too small
- bad position in cockpit
- no redundancy- requires much attention
- no aural warnings
- no direct benefits.
In-flight situation awareness impressions
Short term questionnaires
The following information have been obtained through the short term questionnaires, which focuses
on individual experience made on a special flight.
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It is obvious that in flight the MMI is observed much more than on ground. 78% of the aircrews
observe it at least often.
Looking at the workload, it is mainly increased, precisely for 78% of the aircrews. For 37% of the
aircraft, workload is increased in a high amount.
Comparing the MMI in its present form with the TCAS display, MMI is clearer or more informative
for 78% of the crews, 43% judge the improvement with the best rating. One of the most obvious
advantages of the MMI seems to be displaying the flight numbers with the targets, as indicated in 90%of the answers .
The advantages of the flight number are:
- specific aircraft may be addressed- ATC message "your traffic is..." is easy to identify
- enhanced situation awareness, identification of RT messages
- co-ordination of level request between company aircraft possible- blocking aircraft may be identified
- clearances may be related to specific aircraft
- ATC instructions via RT can be related to aircraft- destination of company aircraft is available.
There is only little improvement of the clearness of the overall traffic situation by means of the MMI.Nevertheless there is a clear tendency that the benefits of the MMI are to be expected in the approach
phase.
Looking at an advanced applications of ADS-B, regarding station keeping, there is a high potential,
but improved equipment is required:
- aircraft symbols were not continuously present- only theoretically
- display too small
- display should be integrated in the navigation display or wind shield display required- ground speed of aircraft to follow required
- coupling to auto pilot required due to short reaction time at 2.5 NM distance.
Another advanced application, parallel approaches in IMC is considered with a high potential, but
again improved equipment is required. The details are:
- ground speed of aircraft required- new procedure required, as follow visually requires good visibility.
Aircraft in the vicinity of the runway could be seen in 20% of the flights, there is a potential for
conflict avoidance referring to runway incursion.
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Comments about in-flight situation awareness are:
- danger of information overload if all aircraft are equipped- more participants required
- MMI better for conflict detection than for approach or separation
- MMI display more clear than TCAS.
Long-term questionnaires:The following information have been obtained through the long term questionnaires, which focuses on
overall experience.
The good rating on a question which looks at collision avoidance in flight by displaying all other
traffic on the MMI, indicates an improvement of the situation, which proofs the high potential of the
system. Workload is not affected in flight. But displaying targets with their flight number using ADS-B already has many advantages. This extension of the TCAS is regarded as highly safety relevant. A
remarkable clarification of the traffic situation is achieved by putting the pilot in the loop of in flight
situation awareness. Being aware of the surrounding traffic situation already helps in planning andoptimisation of the approach. But only little reduction of flight time is expected.
Looking at the optimal vertical band to be displayed as traffic on the MMI the present solution usedwithin TCAS seems to be adequate, with a slight tendency to a lager band. 64% of the crews wish an
option to display all traffic in range.
Looking at EFR (extended flight rules), the scenario to maintain own separation by means of an ADS-
B system is already regarded as possible. But this would mean an increased workload. A very high
potential of the system lies within an optimisation in regards to the achievement of minimumseparation. A higher grade of automation, the transfer of information via data link would lead to the
same results, also leading to more work load, and a better achievement of minimum separation. Still
increasing automation by using a wind shield display would not much improve the possibility tofollow other traffic, but would have positive effects on the workload. Better achievement of minimum
separation is maintained.
An integration of a separation feature in the auto pilot is not necessarily required. There is more need
of a suitable display.
There is no unique position concerning the delegation of responsibilities to the pilots. Yet it seem to be
acceptable already to 55% of the crews in this early stage of the research. Carrying out VMC
procedures in IMC by means of a suitable ADS-B system is feasible for 58% of the crews. And this
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value increases to 74%. using a wind shield display. But this would mean an increased work load, as
stated by 71% of the crews.
Comments about in-flight situation awareness are the following:
- fallback required if system fails
- warning required if minimum separation is not maintained, information level should be thesame for the pilot and ATC
- wind shield display required to be able to look out and view traffic situation at the same
time- danger of to much focusing on the preceding traffic
- wind shield display desirable
- possible conflicts between ATC and pilot duties, in-flight situation awareness needs cleardisplay
- VMC procedures possible at night with the system
- when introducing own separation controller is needed as back up- final responsibility should remain with the controller
- display of traffic according to TCAS filtering desirable
- information welcome, but responsibility in IMC should remain with ATC- problem of unequipped traffic
- enroute own separation possible (>15 NM), during approach work load too high
- enroute own separation possible with nav display, during approach wind shield displayrequired
- overall traffic situation is managed by controller, due to work load own separation possible
only during final approach- long integration phase required.
Economical potential
82% of the crew see economical potential in using an ADS-B system. The details are:
- optimum altitudes, optimal routings, direct routings during free flight- closer separation, continuous and fluent approaches
- more direct routings, requested altitudes available earlier, early co-ordination
- climb through level in IMC possible- shorter routings to maintain safe distance, better directs
- better overview over traffic situation, therefore own flight progress better planable
- reduced separation- optimal speed and approach planning, enhanced safety
- longer direct routings, reduced collision risk
- higher density of traffic may lead to conflicts
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- separation, planning of approach, work load of controller, higher traffic density
- optimal use of airways by applying separation
- climb through level, approach- safety benefits in combination with wind shield display
- altitude and speed co-ordination, maybe within a company
- planning of altitude and shortcuts, better separation during approach, better separation
during departure- more flexibility during en-route, higher chances for tactical decisions
- closer separation
- flow of information in both directions (to crews and to controller)- more direct routings, optimum climb and descents
- more direct routings, shorter approaches and separation
- closer separation, better use of airspace- better timing during approach, e.g. use of flaps, descent planning.
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Annex G. FARAWAY
Details of the FARAWAY applications:
• ADS-B: ADS-B is a surveillance application in which aircraft transmit navigation data and other
parameters to other aircraft and ground systems. The aircraft and ground systems in range of the
transmission are able to receive and process the data for presentation on a display to the local users.• Enhanced Navigation: Enhanced navigation in FARAWAY refers to the use of augmented GPS
to improve the accuracy and integrity of navigation data on the aircraft (compared to not
augmented GPS data). Improving the navigation data allows for more accurate aircraft navigationand also improves the quality of surveillance data reported via ADS-B.
• Data Fusion of Surveillance Information: Data fusion is the merging of surveillance data from
different sources. In FARAWAY, these sources are the radar (PSR/SSR) and ADS-B systems. Thefused data has higher accuracy, integrity and availability than either source on its own. It also
results in more reliable data for conflict detection and conformance monitoring function thus
reducing the probability of false alarms; this is due to the availability of aircraft intent andkinematics data measured on-board and delivered by the ADS-B system.
• TIS-B: TIS-B is an application whereby traffic data is broadcast from a ground station to mobile
users, so that it can be presented on the CDTI. The traffic data is obtained from PSR or SSR andmay be fused with other data sources before being broadcast. The application allows users that are
equipped with VDL Mode 4 ADS-B to have situation awareness of users that are not equipped.
TIS-B thereby offers a straight forward transition solution• Airborne Situation Awareness: Airborne situation awareness refers to the presentation of an air
traffic picture to the cockpit crew. This gives them visibility of the positions and identity of all
aircraft in the vicinity and means that ground controllers and pilots have access to the samesurveillance information.
CDTI specifications
The specifications consist of a description of the following points:
Symbology
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TRAFFIC SYMBOLSCOLOR SYMBOLOGY
TRAFFIC AT SAME FL(within +/- 99 feet)
TRAFFIC AT LOWER FL
TRAFFIC AT UPPER FL
CAUTION(unreliable information)
TRAFFIC SYMBOLS
Traffic displayed without HEADING
OWN AIRCRAFT
Non altitude reporting intruder
white
brown
light blue
yellow
solid diamond
hollow diamond
TEXT TAGS
-02 RELATIVE ALTITUDE(in hundreds of feet)
AF4321 CALL SIGN
CLIMBING/ DESCENDING trend indicator
Traffic displayed with HEADINGas a chevron.
Traffic displayed with HEADINGas an ATC-like vector.
Traffic displayed with related next waypoint
230 FLIGHT LEVEL (AMSL)
Traffic lost whose position is displayedaccording to last position report
Traffic display selection which concerns:
• The different views: heading up, centre or plan
• Horizontal range, altitude, closure, speed bar, altitude tag, callsign tag, flight plan
Warning messages displayed when:
• no aircraft in the vicinity• ADS-B equipment failed
• Ground station out of range
Graphic design rules concerning the symbols:
• Symbols shall not overlap
• range rings shall not interfere with displayed traffic• traffic symbol shall be linked to their respective call sign
In addition, there is a general description covering:
The external interfaces:
• The own aircraft ADC (Air data computer)• the own aircraft AHRS (Attitude Heading Reference System)
• the FARAWAY communication Unit
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• the CDNU control panel
• the CDNU display
Functional breakdown:
To cover CDTI requirements, the following processes are identified:
The following processes ordered from highest to lowest priorities have been identified:• Receive own aircraft update
• Transmit downlink
• Receive uplink• Receive CDTI selection
• Update traffic information
• Compute display situation
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Annex H. PETAL
Documentation overview
For the purpose of this report, available results coming from PETAL-I and PETAL-II have been
collected by reviewing the documents included in the following list:
1. PETAL-II Work Programme and Project Management Document
2. An Operational Description for Maastricht UAC Controllers
3. An Operational Description for Lufthansa Aircrew4. Aircrew_20Q_20V_202_0 - Aircrew questionnaire
5. Overview of the operational procedures allowing aircraft to receive CPDLC messages from
Maastricht ACC6. MMI5000 User’ Manual for PETAL-II – Operational user interaction of message handling in the
MMI5000 system
7. Problem and System Improvement Reporting, Tracking and Resolution8. Data collection and delivery procedures
9. PETAL-II – Interim Report
10. Other useful documents and information downloaded from the PETAL web site:www.eurocontrol.be/projects/eatchip/petal
Technological issues
In order to achieve its objectives, PETAL-II has implemented the following ICAO approved ATSdata-link applications:
• Controller Pilot Data Link Communications (CPDLC): a means of communicationbetween Controller and Pilot, using data link for Air Traffic Control communications.
• Automatic Dependant Surveillance (ADS): a surveillance technique in which aircraft
automatically provide, via data-link, data derived from on-board navigation systems.• Data-link Initiation Capability/Context Management (DLIC/CM): a means of exchanging
addresses, names and version numbers of data-link applications.
In line with the general principle of ‘operations first, technology second’, PETAL implemented these
services using existing airborne, ground, and communications systems and standards. The focus on
controller/pilot exchanges (including some of those considered most critical for use in ATC, such asflight level and direct route clearances) rather than sophisticated system/system functionality, reduced
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development overhead allowing implementation within one year using the Aircraft Communications
and Reporting System (ACARS), VHF data-link infrastructure.
In order to improve the efficiency of current voice standard communication for ATM purposes, the
PETAL project provides the definition and the assessment of the operational procedures, takingadvantage of the NEAN airborne HMI MMI5000 and an intuitive interface for the controllers.
Of course, all the benefits of data communications with respect of voice exchange messages applies.However, it has to be highlighted that a voice communication system shall always be required.
Finally, to involve as many airline partners as possible through the above infrastructures, PETAL-IIhas implemented a ‘multi-stack’ ground system at the Maastricht UAC. This multi-stack front-end
allows aircraft operators to select one or more of the (three) available infrastructures, according to
their individual preferences, participation objectives, and current or planned fleet equipage types,while maintaining infrastructural transparency for the air traffic controllers.
Safety
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Safety assessments have been deeply investigated in the PETAL project. The main results concerning
safety issues are reported in three documents:
• Safety & Performance Requirements (SPR)
• Operational Hazard Assessment (OHA)
• Allocation of Safety Objectives and Requirements (ASOR)
The SPR document provides the safety and performance requirements for air traffic services supported
by Baseline 1 data communications in domestic en route airspace as defined in the documentOperational Environment Definition (OED).
The SPR provides the basis for Institutions to ensure that their operational systems meet applicablerequirements for initial implementation and continued operation.
In particular the SPR document includes:• existing requirements and systems that mitigate identified hazards (e.g., mode C altitude, voice
radio);
• the allocation of the requirements to specific parts of the CNS/ATM system, procedures, andairspace characteristics;
• the identification of approval authority responsible for ensuring initial implementation and
continued operation to meet the allocated requirement;• the traceability to the source of requirements.
The Operational Hazard Assessment (OHA) document provides a qualitative assessment of theoperational hazards associated with introduction of ATS services over data communications as defined
in the OED Baseline 1.
The purpose of the OHA document is to provide an end to end assessment of potential hazards thatresult from a malfunction or failure of data services in applicable operational environments as
specified in the OED. The results of these hazard assessments will be used in the ASOR to generate
safety requirements and implement appropriate risk mitigation strategies for the deployment of dataservices in applicable context and any equivalent operational environment.
A possible set of Allocated Safety Requirements to meet the Safety Objectives established by the
PETAL II OHA have been stated in the ASOR document.
The ASOR document addresses the hazards both for the Airborne segment and the Ground segment by
allocating the identified requirements to the aircrew/aircraft systems and to the ATC/ATSU. Each
“faults” is analysed and, for most of the considered hazards, recommendations/conclusions to mitigatethe hazard are provided.
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Efficiency
In the current air traffic control system, separation and traffic flow management standard procedures
are based on the use of analogue voice communications.
A reliance on increasingly congested voice radio communications for air-ground exchanges is
currently one of the limiting factors on further capacity growth in many sectors of the busier airspace
areas.
In particular, it involves large amounts of time being spent on passing sector co-ordination and
frequency transfer messages, as well as requests by controllers for basic flight information fromaircraft.
On the other hand, data-link functions and services designed within PETAL are specifically targeted tosupport more timely information exchange, thus reducing controller and pilot workload, frequency
congestion and operational inefficiencies surrounding routinely voice communications in the
congested airspace.
Controllers and aircrew using the PETAL operational procedures can make a direct use of data-link to
more efficiently request, deliver, and acknowledge flight level clearances, direct routings, andsector/sector voice communications transfer instructions.
Using the PETAL system, both controllers and the aircrew have more time to plan, monitor and search
for potential conflicts.
As a feedback from users, all of the controllers involved on trials (and interviewed) considered the
PETAL data-link was beneficial in the current mixed (data-link/non data-link equipped) trafficenvironment.
Transition aspects
Rather than a simple set of recommendations, transition aspects are part of an actual implementation
programme in compliance with the international standards and Eurocontrol strategies for theAir/Ground data-link implementation in Europe.
Further information on this transition package is available in various documents, such as the PETAL-
II Work Programme and Project Management Document (WPPM), the PETAL-II End-to-End TrialsSpecifications (and associated draft EUROCAE/RTCA standard), the Safety and Performance
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Requirements (SPR) containing safety and performance criteria for operational approval, and the draft
Institutional Safety Assessment.
In the context of the mentioned Implementation Program, it is envisaged that the air/ground data-linkfunctions implemented at the Maastricht UAC will provide a validated EATMP model of an
Operational System to be extended in Europe.
This issue will be more extensively reported in the PETAL-II Transition Report, not yet issued.
Human factors
PETAL trials have been conducted in an ATC live environment, therefore with human-in-the-loop.
For the purposes of data gathering, aircrew and controllers were requested to complete short writtenquestionnaires following a flight or period of controlling duties, respectively, which involved the use
of data-link communications. From the commencement of PETAL-II flight trials in May 1998, until
temporary suspension of the trial on 31 December 1999, 149 Questionnaires were completed byparticipating aircrew and 81 by controllers at Maastricht UAC. 18 controller interviews were also
conducted. Detailed results coming from the questionnaires are contained in the PETAL-II interim
report.Only to present main relevant aggregate information, some general information about workload and
data-link usefulness are provided in the following.
Useful/not useful: 36% of controllers and 61% of aircrew considered that data-link was a useful
communications tool. Of those controllers (17%) and aircrew (10% overall) who stated that they did
not consider data-link to be useful, many made this observation after experiencing a failure of thesystem.
Workload: generally, both pilots and controllers declared an increased workload due to the use ofdata-link communications, if part of the users involved considered that the increased workload was
due to unfamiliarity with the system.
Institutional aspects
As mentioned before, to achieve its objectives PETAL-II has implemented CPDLC, ADS andDLIC/CM, that are ICAO standardised ATS data-link applications.
The operational context within the European data-link development process is depicted in the picture
below.
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These applications are utilised within PETAL-II through a set of operational services, as defined bythe ODT's ODIAC Sub-Group and published within the Operational Requirements for Air Traffic
Management Air/Ground Data Communications Services Document (ORD), as far as possible in
accordance with the associated ICAO operational standards.PETAL-II has also established a joint reporting agreement with DNA, to cover the effects of down-
linking airborne parameters in approach airspace via Mode-S (the ESCAPADE project).
The PETAL-II information has also had a much greater impact on international standards and
operational data-link implementations than was originally hoped. The most visible evidence of this
effect on International standardisation and implementation are the PETAL-II refinements to thebaseline ODIAC ORD as an international RTCA/EUROCAE industry standard for ATN (ATN
Baseline 1) and its adoption for other implementation programmes in the US and Europe
(EATMP).
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Annex I. TELSACS
In order to increase interoperability, TELSACS defined enhancements of existing functions,
development of new functions and enhancements of the man machine interface.
The following enhancements from the current ACAS were performed:
• improvement of the surveillance function, in order to provide to the collision avoidance logic
additional and more accurate input data about intruders. The surveillance function would take
advantage of both air-air data exchange and uplinked information from the ground• extension of current collision avoidance logic function, using uplinked intruder cleared flight level
• added functionality’s:
– awareness and use of both air-air data and uplinked information– data exchange related to collision avoidance, with the ground system
• enhancement of pilot's HMI, especially related to situation awareness in order to :
– anticipate the intruder trajectory– decrease pilot work load (display of traffic information).
Nevertheless, the TELSACS project aimed at proposing an enhanced ACAS fully compatible withcurrent TCAS II. The enhancements should not preclude the running of TCAS II kernel and should be
implemented as new functions based upon the kernel of TCAS II logic. Also, since ACAS is a last
safety resort, TELSACS aimed at keeping it autonomous from any external (airborne or ground-based)source of information.
The following enhancements of a ground short-term collision avoidance system were implemented:
• improvement of STCA main input, air situation knowledge, using downlinked aircraft cinematic
data• extension of existing STCA functions (trajectory prediction, conflict detection and alert), using
downlinked aircraft parameters
• added functionality’s :– awareness and use of ACAS advisories on the ground
– data exchange related to anti-collision, with the airborne system
– conflict resolution aids• enhancement of controller's HMI, especially related to awareness of ACAS advisories and their
consequences (i.e. flight deviations).
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Therefore, within the TELSACS project, the situation awareness of the pilot has been improved. As
the airborne situation awareness application is considered as the first application before more complex
ASAS applications, the points related to this application were reviewed in detail.
As part of the CARE-ASAS Activity One review, the following point items were covered:
Decision support tools: The existing airborne ACAS system was enhanced with new functions.
Safety issues: A safety evaluation was performed through the evaluation of the concept.
Human factors: A user acceptance evaluation were performed involving pilots and controllers.
Decision support tools
The enhancements are performed on the existing ACAS interface which in itself consists of the trafficdisplay (traffic symbols) and the resolution advisory display (Vertical Speed Indicator with coloured
arcs). The RA display is kept unchanged as the original TCAS II RA display.
Some enhancements to improve pilot awareness of intruding aircraft are added:
• For each intruder the corresponding call sign and air vector are optionally displayed. If this
additional traffic information (call sign, air vector) is not available, the traffic display is identicalto the present TCAS II traffic display.
• The Flight Level Selected (SFL) by the pilot on the pseudo-pilot position (equivalent on thedemonstrator to the Flight Control Unit) is compared with the Flight Level Cleared (CFL) by the
controller. The CFL is uplinked upon new clearance, and the SFL is validated in the adequate
automatic pilot modes.If there is discrepancy (with an error range) between SFL and CFL (in the adequate circumstances
when both data are valid), an indicator on the HMI warns the pilot.
If the situation is assessed as " unwarranted ", the issued TA or RA is considered to be a"moderate TA/RA”.
In the demonstrator two additional features were proposed for evaluation:• Displaying new «moderate TA» symbols
• Displaying new «moderate RA» symbols
In an operational system, adding supplementary symbols would be confusing. The demonstrationsymbols were used for evaluation (to verify that they correspond to really unwarranted advisories)
but they should be replaced by existing TCAS II symbols in an operational system. Therefore, the
latest features were not considered from an operational point of view.
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TELSACS provided detailed specifications of the pilot HMI in [te4].
Safety issues
The assessment of the TELSACS system was based on performance measurements by analysis tool,and in particular it measured safety criteria.
It appeared that the TELSACS system had a notable impact on reducing false alerts and therefore onimproving of safety level.
Human factors
The following conclusions were issued from the experiments performed on the TELSACS
demonstrator:
Pilot’s point of view:
• The improvements of air situation awareness deriving from the enhanced surveillance functionand the HMI improvements have been considered by the majority of pilots as satisfactory.
• They consider the adopted symbology and presentation very intuitive and useful and they agreedto introduce partially (and in some cases totally) some of the enhancements defined in TELSACS.
• The use of the CFL/SFL to modulate the relevance of a TA/RA is considered by the majority ofpilots useful to suppress the moderate TA/RA due to the fact that most of the time they represent
unwarranted TA/RA; however there is no unanimity on this aspect.
• Pilots were generally satisfied also for the way the TA/RA information was shown (displayed
labels, symbols, texts, colours, etc. ); in addition most of the visual enhancements proposed during
the simulations (i.e. display of up-linked CFL) were appreciated and found useful/very useful bythe majority of pilots.
• Regarding the pilots’ workload the majority of them consider, at this stage of the project, theenhancements introduced as requiring the same amount of workload with respect to the current
situation; this was due to the fact that additional training was required to manage and interact with
new/additional data and to refine some of the proposed information.
Controller’s point of view:
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• TELSACS system allowed to increase the level of confidence in aircraft position, safety net and
STCA warning time due to the improved information support providing integration of both air and
ground systems. This had as consequence a relevant improvement of the air situation awareness.
• The reduction of the false alarm rate and the automatic transmission of traffic information to the
aircraft reduce the controller’s workload.
• The use of colours, shapes and sizes employed to display conflict situations, and in general all the
HMI improvements, was found good/very good by controllers.
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Annex J. OCD EXECUTIVE SUMMARY
This document contains a high-level description of the proposed target operational concept for Europe
for 2015 based on the main operational and functional options available to realise the overall objectiveset out in the ATM Strategy for 2000+:
´For all phases of flight, to enable the safe, economic, expeditious and orderly flow of traffic
through the provision of ATM services which are adaptable and scaleable to the requirements ofall users and areas of European airspace. The services shall accommodate demand, be globally
inter-operable, operate to uniform principles, be environmentally sustainable and satisfy national
security requirements.´The concept describes the types and scope of ATM services needed to meet both the forecast increase
in air transport movements, and the airspace users’ 3 expectations for more flexible and cost-effective
ATM services. The document sets out the main options that are available and highlights thedifferences between these options in terms of likely benefits and trade-offs. However, because of the
uncertainties inherent in forecasting some longer-term events, not all of the issues surrounding the
target concept are, or can be, fully explored or resolved at this stage.Traffic forecasts indicate that air traffic in the ECAC region will more than double by 2015. Some
parts of the airspace in Europe are already congested, and cannot absorb even today’ s levels of
demand at busy times. Airspace users also want a more cost-effective and flexible ATM networkwhich is responsive to their business needs. This generates the requirement for integrated ATM
services which encompass gate-to-gate operations and considers ATM as part of a complex network
involving the aircraft operators and airports to ensure that the best use is made of all availableresources. It is also necessary to improve the levels of safety to reflect the increase in aircraft
movements. The main drivers for change in the ECAC region airspace are the need to simultaneously
create additional capacity in the congested airspace areas while reducing direct and indirect ATM-related costs, and to increase safety levels. Current ATM concepts and national infrastructures have
inherent limitations and will become progressively less than adequate as traffic levels rise. Airport
congestion, in particular, is likely to become a major concern and constraint on future aviation growth.It is possible to identify some strong trends in the way that air transport and ATM might develop based
on agreed policies and strategies. Nevertheless, there are uncertainties surrounding the feasibility of
some potential concept options and a number of possible choices as to which change path to follow,each of which has its own balance in terms of costs, and the capacity and flight efficiency gains which
could be achieved.
The main concept options range between a ‘ managed’ ATM environment based on traffic structuring,greater traffic predictability, longer planning horizons and extensive automated support, to a ‘ free
flight’ environment based on free routings and autonomous aircraft separation. In practice, the target
concept will have to contain elements of most of the available options to meet the varyingrequirements of all of the airspace users and the differing types of regional traffic conditions.
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However, the overriding need is to generate extra capacity in the busiest traffic areas while increasing
safety levels.
The ATM Strategy for 2000+ provides management framework for making collaborative decisions asto which options are feasible and cost-effective according to the circumstances being addressed.
The concept incorporates a mix of route structuring, free routings and autonomous aircraft The target
concept is predicated on layered planning, based around a strategically-derived ‘ daily airspace plan’ ,with collaborative decision making between the involved parties and with an evolving change to
managing resources rather than demand. ATM is considered as a network
which includes airports and ECAC region airspace, including that in TMAs and around airports,as a continuum for airspace planning and flight management purposes in order to optimise the
available resources. Airspace divisions are based on ATM needs rather than on national
boundaries, but without compromising sovereigntyoperations to answer the needs of a diverseuser community. The concept involves fundamental changes to current roles both in the air and
on the ground; a distribution of responsibilities for separation assurance between the air and ground
ATM elements according to aircraft capabilities and the services provided; greater use of computersupport tools to cope with increased levels of service and to keep ATC and cockpit workload within
acceptable levels; and a more dynamic and flexible management of airspace.
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