GEORGE BEST BELFAST CITY AIRPORT AIRBORNE AIRCRAFT …...Bombardier . Dash 8-Q400, Let L-410) and...

GEORGE BEST BELFAST CITY AIRPORT

AIRBORNE AIRCRAFT NOISE CONTOURS

SUMMER 2011

Report to

George Best Belfast City Airport

Sydenham By Pass

Belfast

BT3 9JH

A9443 R01 NW

November 2011

Bickerdike Allen Partners

2

CONTENTS

Page No

1.0 INTRODUCTION .......................................................................................................................... 3

2.0 AIRCRAFT OPERATIONS .......................................................................................................... 3

2.1 General ..................................................................................................................................... 3

2.2 Traffic Distribution by Aircraft Type ........................................................................................... 3

2.3 Flight Tracks .............................................................................................................................. 7

2.4 Traffic Distribution by Route ...................................................................................................... 7

2.5 Flight Profiles ............................................................................................................................ 8

3.0 INM MODEL ................................................................................................................................. 8

3.1 Methodology .............................................................................................................................. 8

4.0 RESULTS ................................................................................................................................... 10

4.1 Daytime (16h) Contours .......................................................................................................... 10

4.2 Population Counts ................................................................................................................... 12

5.0 SUMMARY ................................................................................................................................. 13

Figure 1: Departure Routes

Figure 2: Daytime Summer Noise Contours 2011 - 54, 57, 60, 63, 66 and 69 dB LAeq,16h

Figure 3: Comparison of Daytime Noise Contour 2011 with DoE Indicative Noise Contour 63 dB LAeq,16h

Figure 4: Comparison of Daytime Noise Contour 2011 with DoE Indicative Noise Contour 60 dB LAeq,16h

Figure 5: Comparison of Daytime Noise Contour 2011 with 2010 Daytime Noise Contour 63 dB LAeq,16h



Appendix A Airport Contour Validation - Noise

Appendix B Airport Contour Validation - Tracks


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1.0 INTRODUCTION

This report records the result of noise contouring work undertaken to produce actual airborne

noise contours for the summer period in 2011 for George Best Belfast City Airport (GBBCA)

Noise contours have been produced for the 92 day summer period in 2011 using the actual

aircraft movements and the Federal Aviation Administration (FAA) prediction methodology,

the Integrated Noise Model (INM) Version 7.0b. This methodology has been validated using

results from the noise monitoring terminals (NMTs) installed at GBBCA for the most common

aircraft types operating there.

Noise contours have been produced annually for GBBCA for several years. Those for 2010

were reported in Bickerdike Allen Partners (BAP’s) report Ref: A7877/DC/R01 dated

November 2010.

This report sets out the assumptions used in the computation of the contours for 2011. The

resulting contours are also included as are population counts for the key noise exposures.

2.0 AIRCRAFT OPERATIONS

2.1 General

The aircraft movement data, submitted by GBBCA in the form of daily ATC logs, has been

assessed in relation to aircraft type, departure and arrival route, stage length and runway

usage to enable input into the noise computation program, the Integrated Noise Model (INM).

This section of the report describes how this briefing information has been compiled in a form

suitable for analysis purposes and considers the following:

- Traffic Distribution by Aircraft Type

- Flight Tracks

- Traffic Distribution by Route

- Dispersion

- Flight Profiles

2.2 Traffic Distribution by Aircraft Type

The basis for the noise contours is the actual movements in 2011 during the 92 day summer

period, 16th June to 15th September. This is the usual period taken when producing noise

contours in the U.K. and in most cases represents a worst case as airport traffic generally

peaks in the summer due to holidays.


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The actual movements are a combination of the passenger movements, any freight

movements, and the non commercial movements which include any training flights. Detailed

information was provided for all aircraft movements during the 92 day period in 2011.

Although there are a number of early morning movements between 0630 hours and 0700

hours over the 92 day period, for the purposes of this study all movements are assumed to

take place within the “daytime period” of 0700 hours to 2300 hours.

As with all modelling programs every aircraft type is not specifically included in the INM model

and substitutions are used. This is particularly the case with the smaller types. For each of the

actual aircraft types the recommended INM aircraft type has been adopted. For the majority of

the larger aircraft this does not involve a change but for the smaller types, and in particular the

general and business aviation aircraft several aircraft types have been grouped together and

represented by one INM substitute aircraft type.

Table 2.1 shows the 2011 aircraft split over the 92 day summer period and how these have

been modelled in INM.

The actual non commercial movements from 2011 also include 37 movements by helicopters.

Earlier versions of the INM software were not able to model helicopter movements and so

they were excluded for the contours produced for 2005, 2006, and 2007. They have also been

excluded for the contours produced for 2008, 2009 and 2010, as given the noise output of the

helicopter movements and considering they comprised around 1% of the total movements

with a prevalence of larger jet aircraft, their continued omission was not considered significant.

In 2011 helicopters comprised under 1% of the total movements, and so for the same reasons

as in 2008, 2009 and 2010 their continued omission is not considered significant to the overall

contours and maintains consistency with previous contouring.


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Aircraft Type INM Designator

Total No. of Movements

over 92 Days

% of Total Movements

Airbus A319 A319-131(1) 732 6.62% Airbus A320 A320-211 188 1.70% Airbus A321 A321-232 12 0.11% Boeing 737-300 737300(1) 1323 11.97% Boeing 737-400 737400 61 0.55% Boeing 737-500 737500(1) 158 1.43% British Aerospace BAe 146-100 & 146-200 BAE146 2 & 5 0.06% Embraer EMB-145 EMB145 104 0.94% Embraer 195 GV(1) 1266 11.46% Bombardier Dash 8-Q400 DHC830(1) 6197 56.08% Dornier-228 DO228 4 0.04% Dornier-328 DO328 2 0.02% Let L-410 DHC6(1) 619 5.60% Saab 2000 HS748A 2 0.02% Saab 340 SF340(1) 130 1.18% Cessna 510 CNA510 4 0.04% Cessna 525 CNA500 5 0.05% Cessna 550 & Beechcraft Beechjet 400 MU3001 21 & 23 0.40% Canadair CL600 Challenger & Dassault Falcon 2000 CL600 6 & 2 0.07% Cessna Citation Excel (560X) CIT3 61 0.55% Gulfstream G150 IA1125 2 0.02% Gulfstream G550 GV 25 0.23% Learjet 45 & British Aerospace BAe 125-800 LEAR35 2 & 15 0.15% Beech Super King Air 200 & British Aerospace BAe Jetstream 31 DHC6 18 & 18 0.33% Pilatus PC-12 CNA441 25 0.23% Cessna 303 Crusader BEC58P 3 0.03% Cessna 172 Skyhawk CNA172 2 0.02% Rockwell Aero Commander 112 GASEPF 4 0.04% Piper PA-31 Navajo Chieftain PA31 6 0.05% Piper PA-42 Cheyenne III PA42 3 0.03% 11050 100.00%

Table 2.1 Aircraft Types used in INM 2011

Note 1: For the types highlighted validation has found modifications are required to the INM standard assumptions

as detailed in Section 3.1.2.

For comparison purposes, aircraft types and associated movement numbers used to generate

the 2010 INM contours are given in Table 2.2.


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Aircraft Type INM Designator

Total No. of Movements

over 92 Days

% of Total Movements

Airbus A319 A319-131(1) 1147 10.62% Airbus A320 A320-211 213 1.97% Airbus A321 A321-232 8 0.07% Boeing 737-700 737700 54 0.50% Boeing 737-800 737800 2368 21.93% British Aerospace BAe 146-200 BAE146 28 0.26% Embraer EMB-145 EMB145 22 0.20% Embraer 195 GV(1) 1676 15.52% Avions de Transport Regional ATR-42 DHC8 122 1.13% Avions de Transport Regional ATR-72 HS748A(1) 8 0.07% Bombardier Dash 8-Q400 DHC830(1) 4247 39.34% Dornier-228 DO228(1) 30 0.28% Let L-410 DHC6(1) 426 3.95% Saab 340 SF340(1) 134 1.24% Beechcraft Beechjet 400, Cessna 550 Citation II & Cessna 560 Citation V

MU3001 4, 30 & 3 0.34%

Bombardier Global Express F10065 4 0.04% Cessna Citation II & Cessna Citation Jet CNA500 6 & 6 0.11% Canadair CL600 Challenger & Dassault Falcon 2000 CL600 10 & 2 0.11% Cessna Citation Excel (560X) CIT3 56 0.52% Gulfstream GIV GIV 8 0.07% Gulfstream GV GV 10 0.09% IAI 1126 Galaxy CNA750 2 0.02% Learjet 35, 40, 45 & British Aerospace BAe 125-800 LEAR35 4, 4, 6 & 22 0.33% Beech Super King Air 200, Beech Super King Air 350 & Swearingen Merlin IV DHC6 7, 2 & 43 0.48% Beech King Air 90 & Pilatus PC-12 CNA441 2 & 40 0.39% Beechcraft Model 60 Duke, Britten Norman BN-2A Islander & Socata TBM-700 BEC58P 2, 2 & 2 0.06% Cessna 172 Skyhawk CNA172 4 0.04% Cessna 182 Skylane CNA182 2 0.02% Cirrus SR22 GASEPV 2 0.02% Robin DR400 GASEPF 2 0.02% Piper PA-28 Warrior & PA-28 Turbo Arrow PA28 4 & 2 0.06% Piper PA-31 Navajo Chieftain PA31 10 0.09% Piper PA-31T Cheyenne 2 CNA441 4 0.04% Piper PA-34 Seneca PA34 6 0.06% 10796 100.00%

Table 2.2 Aircraft Types used in INM 2010

Note 1: For the types highlighted validation found modifications were required to the INM standard assumptions as

detailed in the previous report, Ref: A7877/DC/R01.


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The overall movement numbers are similar in 2011 to 2010, having increased by around 2%.

The commercial aviation still consists mainly of twin engined turboprop aircraft (e.g.

Bombardier Dash 8-Q400, Let L-410) and twin engined turbofan aircraft (e.g. Boeing 737,

Airbus A320 family, Embraer 195).

The mix of these aircraft has changed in 2011, with the Bombardier Dash 8-Q400 making up

56% of the movements compared to 39% the previous year. The Let L-410 movements also

increased from 4% to 6%, while the most common turbofan aircraft all had fewer movements

in 2011 than 2010. In addition to this, the Boeing 737-800, which made up 22% of the

movements in 2010, did not operate in 2011 and was replaced by the Boeing 737-300, which

did not operate in 2010 but made up 12% of the movements in 2011.

2.3 Flight Tracks

A validation exercise has been undertaken to validate the flight tracks used in the INM model.

The results of this exercise are shown in Appendix B. The main departure tracks are shown in

Figure 1.

2.4 Traffic Distribution by Route

The overall runway usage during the 2011 summer period is given in Table 2.3. For the

modelling the actual usage by aircraft type was used.

Runway Arrivals Departures

04 24.0% 37.3%

22 76.0% 62.7%

Table 2.3 Summer 2011 Runway Usage

This overall runway usage shows an increase in operations on runway 04 compared to 2010

by around 5% of the total movements.

For each runway there is a single arrival route. There are four assumed departure routes on

runway 04, and one initial departure route on runway 22. The method of determining the split

of aircraft between these routes is discussed in Appendix B.


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2.5 Flight Profiles

For the departure movements the INM model offers a number of standard flight profiles for

most aircraft types, and in particular for the larger aircraft types. These relate to different

departure weights which are greatly affected by the length of the flight, and consequently the

fuel load. In the INM model this is referred to as the stage length and is initially in increments

of 500 nautical miles. The INM model assumes all aircraft take off with a full passenger load

irrespective of stage length. As the stage length increases the aircraft has to depart with

greater fuel and so its flight profile is slightly lower than when a shorter stage length is flown.

The standard option when producing contours using INM is to use destination information for

the departures to select the stage length for determining the departure flight profile. For all

aircraft operating from the airport stage length 1 is assumed with the exception of the Airbus

A320. For this aircraft type, following the validation exercise which is discussed in Section

3.1.2, stage length 2 has been used.

3.0 INM MODEL

3.1 Methodology

3.1.1 General

All contours and population counts are determined using the Integrated Noise Model (INM)

version 7.0b software and a postcode/population database. This latest version of the INM

software has been available since 30 September 2009 and was also used for the 2009 and

2010 contours.

The Integrated Noise Model (INM) software evaluates aircraft noise in the vicinity of airports

using flight track information, aircraft fleet mix, standard defined aircraft profiles, user-defined

aircraft profiles and terrain. INM is used to produce noise exposure contours as well as predict

noise levels at specific user-defined sites.

INM allows population points to be defined in a particular study. Each point consists of a Point

ID, a latitude, a longitude and a population value for the point. If the population point lies

within the threshold of a particular contour then the population value is included in the total

count within the contour.


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The population data has been derived from census information and has been supplied by

CACI Ltd. Strictly for the contours produced for 2010 the population data was the CACI Ltd

estimate for 2008 and this has also been used for the 2011 contours.

3.1.2 Assumptions

George Best Belfast City Airport data relevant to the INM study is taken from the latest edition

of the UK Aeronautical Information Package.

As with all modelling programs not every aircraft type is specifically included in the INM model

and substitutions are required. Details regarding aircraft types are given in Section 2.2.

A 3.0° approach angle is used for all aircraft and the ground topography is assumed to be flat.

The INM default headwind of 14.8 km/hr is assumed.

The INM version 7.0b has two options for lateral attenuation, one relates to acoustically soft

ground such as grassland and the other hard ground such as built up areas and water. Due to

the presence of the Lough and the other hard surfaces around the Airport hard ground was

assumed for the contours produced before 2010. This had the effect of reducing the

attenuation of noise from propeller driven aircraft but did not affect jet aircraft. The different

approach to lateral attenuation based on the aircraft type is given in the relevant standards

which aim to reflect actual performance.

As noted earlier advice has been received from the Civil Aviation Authority on the assumption

to be made regarding the ground, specifically that acoustically soft ground should be

assumed. This was therefore used for the 2010 contours, and has again been used for the

2011 contours.

For some aircraft types it has been necessary to modify the standard INM assumptions. This

was also done for the earlier contours. For those produced for before 2008 modifications were

made when the INM predictions did not agree with FAA certification data for specific aircraft.

For the 2008 contours the partial installation of the permanent Noise Monitoring Terminals

(NMTs) at GBBCA had occurred and comparison was made with the initial results from these.

The installation of the permanent Noise Monitoring Terminals (NMTs) at GBBCA was

completed in 2008 so for the 2009 contours onwards a significant amount of measured noise

data has been made available. Results from the period September 2010 to September 2011

have been used for the 2011 validation exercise to review the INM assumptions for the

common aircraft types as detailed in Appendix A.


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The 2011 validation exercise found that modifications were required for several aircraft types,

to better model their operations at GBBCA. These included types such as the Bombardier

Dash 8-Q400 and Embraer 195 for which the INM does not contain specific data. The result is

that the modelled noise characteristics of these aircraft have been adjusted by modifying the

INM aircraft used and/or the actual movement numbers flown during the period when

producing the contours. These adjustments are detailed in Table 3.1.

Initial INM Type Substitution Modification to Movement Numbers

Departures Arrivals

Airbus A319 A319-131 A319-131 * 1.4 A319-131 * 1.5

Boeing 737-300 737300 737300 * 1.7 737300 * 1.7 Boeing 737-500 737500 737500 * 1.9 737500 * 1.7 Embraer 195 A319-131 A319-131 * 2.0 A319-131 * 2.0

Bombardier Dash 8-Q400 DHC6/SD330 DHC6 * 0.8 SD330 * 1.4

Dornier -228[1] DO228 DO228 x 2.0 DO228

Let L-410 DHC6/SD330 DHC6 * 1.8 SD330

Saab 340 SF340 SF340 * 2.5 SF340 * 2.0

Table 3.1 Modifications to INM Assumptions used for 2011 Contours Note 1: For the Dornier-228 there were insufficient movement numbers to assess it as part of the 2011 validation

exercise. As such the 2010 validation has been used.

These modifications to INM assumptions are similar to those used for the 2010 contours, and

for the Dornier-228 and Embraer 195 they are identical. For a number of the other types there

is a small change in the factor applied, for example for the Airbus A319 on departure an

increase from 1.3 to 1.4. The largest relative change in factors is for the Bombadier

Dash 8-Q400 on departure, a decrease from 1.0 to 0.8.

4.0 RESULTS

4.1 Daytime (16h) Contours

Noise contours have been produced for the 16 hour daytime period, 07:00 hours to 23:00

hours, based on the actual movements for the summer 92 day period in 2011. The 16 hour

daytime contours of this type, shown in Figure 2, have been used for many years in the UK to

assess noise impact. Contour areas are given in Table 4.1 and are compared with the contour

areas for 2010.


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Figure 3 shows a comparison between the 63 dB LAeq,16hr daytime contour based on the 2011

movements and the DoE indicative contour resolved in 1997. The 2011 contour is shorter but

slightly wider than the indicative contour in some locations. However, there are no residential

properties within the 2011 contour at these locations.

Figure 4 shows a comparison between the 60 dB LAeq,16hr daytime contour based on the 2011

movements and the DoE indicative contour. The 2011 contour is again slightly wider than the

indicative contour in some locations and contains some additional properties located in

Sydenham to the east of the A2. However due to it being shorter, the 2011 contour does not

extend as far into Ballymacarrett or contain as many properties in the Kinnegar area of

Holywood as compared to the indicative contour.

Figures 5 to 7 show comparisons between 2011 and 2010 for the 63, 60 and 57 dB LAeq,16hr

contours respectively. Table 4.1 shows the difference in area between the 2011 and 2010

LAeq,16hr contours.

Contour Level

LAeq,16h, dB

Area of Daytime Air Noise Contours (km2)

Decrease in Contour Area 2011 v 2010

2011 2010

54 8.89 10.94 18.7%

57 4.57 6.10 25.1%

60 2.27 3.18 28.6%

63 1.17 1.60 26.9%

66 0.65 0.87 25.3%

69 0.40 0.54 25.9%

Table 4.1 Comparison between 2011 and 2010 Noise Contour Areas

Table 4.1 shows that the 2011 contour areas are consistently smaller than those for the 2010

contours, on average by 25%. Figures 5 to 7 show that the 2011 and 2010 contours are very

similar in shape with the contours for 2011 being uniformly smaller.

The decrease in contour area from 2010 to 2011 can be largely attributed to the change in

aircraft mix, as the louder turbofan aircraft which made up 49% of the movements in 2010

only made up 30% of the movements in 2011. The update of the validation exercise to include

the more recent measured noise levels also led to some decreased factors to be applied to

certain aircraft types, in particular the Bombadier Dash 8-Q400, which made up over 50% of

the movements.


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4.2 Population Counts

Population counts for the 2011 and 2010 LAeq,16hr daytime contours are given in Table 4.2 and

Table 4.3.

Contour Level

LAeq,16h, dB

Population

2011 2010

54 17412 23810

57 6195 11422

60 573 3192

63 0 0

66 0 0

69 0 0

Table 4.2 Comparison between 2011 and 2010 Population Counts – Cumulative

Totals

Year Population by Contour Band (dB LAeq,16h) Total

> 69 66 - 69 63 - 66 60 - 63 57 - 60 54 - 57

2011 0 0 0 573 5622 11217 17412

2010 0 0 0 3192 8230 12388 23810

Table 4.3 Comparison between 2011 and 2010 Population Counts

Tables 4.2 and 4.3 show that there is an decrease in the populations assessed within the

contours from 2010 to 2011. There are still no properties exposed to 63 dB LAeq,16h. For those

in the 60 to 63 dB LAeq,16h contour band, the population decrease is around 82%. This is

significantly greater than the corresponding decrease in contour area which is around 29%.

The difference arises as the local population is not evenly distributed over the contour area so

changes in contour area can have no effect on the population contained or disproportionate

effects depending on the location of the additional area.

The reduction in population in the 60 to 63 dB LAeq,16h contour band is mainly located in

Sydenham and Ballymacarrett. Based on the decrease in contour area the change in noise

level is estimated at between 1 and 2 dB(A).

For the other contour bands the relative change in population is much less, around 32% for 57

to 60 dB LAeq,16h and around 9% for 54 to 57 dB LAeq,16h.


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5.0 SUMMARY

LAeq,16h noise contours have been produced, and population counts made, based on the actual

movements during the 92-day, summer period in 2011.

The 2011 contours extend slightly outside the DoE indicative contours in places but lie well

inside in other places. For the 60 dB LAeq,16h contour a small number of properties in an area

of Sydenham east of the A2 are within the 2011 contour but not the indicative contour.

The 2011 LAeq,16hr contours are very similar in shape, but smaller by on average 25%, to the

2010 LAeq,16hr contours. This is attributed to a decrease in the proportion of turbofan aircraft in

the mix and some changes in the validation of aircraft types operating at GBBCA.

The assessed population within the 2011 contours is fewer than that within the 2010 contours.

This is due to 2011 contours being uniformly smaller and so not extending as far south of the

Airport over parts of the populated areas of Sydenham and Ballymacarrett.

Nick Williams David Charles Peter Henson for Bickerdike Allen Partners Associate Partner


Appendix A

Airport Contour Validation – Noise


A.1

AIRPORT CONTOUR VALIDATION – NOISE INTRODUCTION

Summer noise contours have been prepared for George Best Belfast City Airport (GBBCA)

based on the actual movements during the summer period for a number of years. This has

involved the use of the Federal Aviation Administration (FAA) prediction methodology, the

Integrated Noise Model (INM), which is regularly updated. Consequently over the years, noise

contours have been produced using different versions.

The INM is used around the world in over 50 countries and consequently is flexible enough to

allow local circumstances to be taken into account. This can be achieved by entering specific

departure routes, operational profiles or weather conditions but also by modifying or creating

specific noise information for aircraft types.

As a way of checking on the accuracy of the modelling, validation exercises have been

conducted which compare predicted noise levels for individual aircraft movements with either

published noise certification levels or noise levels measured at Belfast. This is particularly

useful for aircraft types where the INM does not have actual data and so suggests a substitute

type or where no mention is made of an aircraft type at all.

CURRENT VALIDATION

Validation using NMT Results

The validation exercise for the 2010 contours used all the measured results from the

permanent noise monitoring system at Belfast City Airport (GBBCA) since installation.

Specifically results were used from the Noise Monitoring Terminal (NMT) at Nettlefield

Primary School (MP01), which is approximately 4.5 km from the start of roll location of runway

22, for the period July 08 to August 2010. Results obtained over the periods January 2009 to

March 2009 and August 2009 to August 2010 from the NMT (MP02) at the Kinnegar Army

Camp, which is approximately 3.9 km from the start of roll location of runway 04, were also

used. This resulted in over 60,000 individual aircraft measurement to review the assumptions

made in the computer modelling of the airborne aircraft noise.

To allow any changes in the measured noise levels of the aircraft to be taken into account the

validation exercise for the 2011 contours uses the most recent results form the NMT’s.

Specifically the results for the period September 2010 to September 2011 have been used

which comprise over 42,000 individual aircraft measurement.


A.2

The resulting average measured noise levels used for the validation exercises in 2010 and

2011 are given in Table A1 for the most common aircraft types that operated in both the 2010

and 2011 summer periods. This shows that the average measured noise levels for these

types have not varied by more than 0.5 dB indicating consistent performance.

Aircraft Type Operation 2010 Validation Measured Noise Levels

(SEL dB)

2011 Validation Measured Noise Levels

(SEL dB) Average No. Average No.

Airbus A319 Arrival Rwy 04 85.1 701 85.3 466 Arrival Rwy 22 88.8 1346 88.9 1634

Departure Rwy 04 89.5 539 89.8 550 Departure Rwy 22 87.7 1963 88.1 1496

Embraer 195 Arrival Rwy 04 87.4 1206 87.5 523 Arrival Rwy 22 90.1 2765 90.2 2007


Bombardier Dash 8-Q400

Arrival Rwy 04 83.0 3258 82.9 2239 Arrival Rwy 22 86.5 7499 86.4 9057


Table A1 Measured Noise Levels used for Validation in 2010 & 2011

The 2011 exercise has considered the most common 8 aircraft types which comprised around

95% of the summer period movements in 2011. These are also the types for which there is

generally the most measured results at the monitors.

For each aircraft type there are four sets of measured results, for arrivals and departures at

each of the two monitors. As the monitors are not located symmetrically with regard to the

runway the noise levels at each will differ and so they need to be considered separately. For

the individual movements within a set there is some variation, so every arrival by an aircraft

type does not produce exactly the same noise level. There are a number of factors which

contribute to this, in particular the weather conditions.

Measured Results

The spread of results is illustrated in Figures A1 to A4. These show the distribution of

measured noise levels from September 2010 to September 2011 for the most common

operations, arrivals from the north and departures to the south, for the most common aircraft

types in the summer period of 2011, the Boeing 737-300 and the Bombardier Dash 8-Q400.


A.3

0%

5%

10%

15%

20%

25%

30%

35%

40%

82 83 84 85 86 87 88 89 90 91 92 93

SEL (dB)

0%

5%

10%

15%

20%

25%

30%

35%

40%

86 87 88 89 90 91 92 93 94 95 96 97

SEL (dB)

Figure A1 – Boeing 737-300 Departures Figure A2 – Boeing 737-300 Arrivals

on Runway 22 on Runway 22

0%

5%

10%

15%

20%

25%

30%

35%

40%

77 78 79 80 81 82 83 84 85 86 87 88

SEL (dB)

0%

5%

10%

15%

20%

25%

30%

35%

40%

82 83 84 85 86 87 88 89 90 91 92 93

SEL (dB)

Figure A3 – Dash 8-Q400 Departures Figure A4 – Dash 8-Q400 Arrivals

on Runway 22 on Runway 22

The distributions have the large majority of measured noise levels closely grouped together

around the averages, shown as a vertical red line on the figures, with a pattern that

approximates to a normal distribution with a standard deviation of less than 2 dB. Such

distributions of measured noise levels are commonly found at Airport fixed noise monitors at a

similar distance from the runway.


A.4

From the distributions of measured noise levels for each of the aircraft types considered the

averages have been determined and compared to INM standard predicted noise levels. Table

A2 gives the latest measured average noise levels for the most common 4 aircraft types in the

2011 summer period which comprised over 85% of movements.

Aircraft Type Operation Measured Noise Levels (SEL dB)

INM Standard Assumptions

Average No. Type Level (SEL dB)

Airbus A319 Arrival Rwy 04 85.3 466 A319-131 83.7 Arrival Rwy 22 88.9 1634 86.7

Departure Rwy 04 89.8 550 87.9 Departure Rwy 22 88.1 1496 87.0

Boeing 737-300

Arrival Rwy 04 90.3 344 737300 88.0 Arrival Rwy 22 93.0 1524 90.9


Embraer 195 Arrival Rwy 04 87.5 523 GV 81.8 Arrival Rwy 22 90.2 2007 84.7



Arrival Rwy 04 82.9 2239 SD330

82.2 Arrival Rwy 22 86.4 9057 84.5

Departure Rwy 04 80.8 3608 DHC6

82.1 Departure Rwy 22 80.4 6981 81.6

Table A2 Measured and Standard Predicted Noise Levels

Predicted Results

Also included in Table A2 are the standard INM aircraft types for the turbofan aircraft and the

resulting predicted noise levels. For the Bombardier Dash 8-Q400 the INM does not offer a

standard type so types have been chosen based on the earlier validation findings. For all the

departure predictions above Stage Lengths of 1 have been used, which equate to flights of up

to 500 nm. This agrees with the earlier validation findings for the Airbus A319 and is the only

Stage Length available for two of the other types.


A.5

Approach to Validation

The approach to validation modifications has been to only change from the INM standard

type, when the measured results show clear divergence, e.g. an apparent prediction error in

excess of 1.5 dB. Also the approach seeks to determine any modification by aircraft type and

aircraft operation, but not also by runway used. This means one modification is adopted for all

arrivals by an aircraft type, and one for all departures by an aircraft type.

Comparison of Measured and Predicted Results (Table A2)

For the Airbus A319 on arrival the predicted noise levels are lower than the measured

averages, in one case but just over 2 dB, and so a modification has been made. This is to

increase the modelled number of arrival movements of this aircraft by a factor of 1.5. For

departures the predicted noise levels are also lower than the measured averages, in one case

by almost 2 dB, and so a modification has been made. This is to increase the modelled

number of departure movements of this aircraft by a factor of 1.4.

For the Boeing 737-300 on arrival the predicted noise levels are lower than the measured

averages by around 2 dB, and so a modification has been made. This is to increase the

modelled number of arrival movements of this aircraft by a factor of 1.7. For departures the

predicted noise levels are also lower than the measured averages, in one case by around

3 dB, and so a modification has been made. This is to increase the modelled number of

departure movements of this aircraft by a factor of 1.7.

For the Embraer 195 on arrival the predicted noise levels for INM standard type GV are lower

than measured and so a modification has been made. This is to change to an alternative INM

type, A319-131, and also increase the modelled number of arrival movements of this aircraft

by a factor of 2. This has the effect of increasing the predicted noise levels so they are within

1 dB of those measured. For departures the same issue arises and the same modification has

been made, see Table A3 below.

For the Bombardier Dash 8-Q400 on arrival the predicted noise levels for INM type SD330 are

lower than measured, particularly for operations on runway 22, and so a modification has

been made. This is to increase the modelled number of arrival movements of this aircraft by a

factor of 1.4. This has the effect of increasing the predicted noise levels by 1.5 dB and

reduces the differences to those measured. For departures using the INM type DHC6 there

are over predictions of just over 1 dB. A modification has therefore been made to decrease

the modelled number of departure movements of this aircraft by a factor of 0.8.


A.6

This exercise has also been undertaken for the other types and the final validation

modifications are summarised in Table A3. These have been used for the 2011 contours.

Aircraft Type INM Standard Assumptions

Adjustments following Initial Validation Departures Arrivals

Airbus A319 A319-131 A319-131 Moves * 1.4 A319-131 Moves * 1.5 Airbus A320 A320-232 Stage Length 2 -

Boeing 737-300 737300 737300 * 1.7 737300 * 1.7 Boeing 737-500 737500 737500 * 1.9 737500 * 1.7


- DHC6 * 0.8 SD330 Moves x1.4

Embraer 195 GV A319-131 Moves x 2 A319-131 Moves x 2 Let L-410 - DHC6 Moves * 1.8 SD330 Saab 340 SF340 SF340 Moves * 2.5 SF340 Moves * 2

Table A3 2011 Validation Modifications

Table A3 shows that for four aircraft types where INM does have specific data modifications

have been made. For the Airbus A319 arrival movements have been factored up and so have

the departures to a similar extent. Similar adjustments have been made for the Boeing

737-300 and 737-500 and the Saab 340 movements, with both arrivals and departures being

factored up.

The need for modifications for the larger aircraft types in particular is not unexpected as they

are available in a range of specifications with different engine types, sometimes from different

manufacturers. This means that the actual type operated by the airline may differ to the one in

the INM model and this is the case here for Boeing 737-300.

For the Let L-410 the software does not suggest a type. The validation finds that using the

Dash 6 (DHC6) with movement numbers factored up for departures and the Shorts 330

(SD330) for arrivals agrees well with measured noise levels.

Effect of Validation

The effect of the validation exercise on the predicted noise levels for the four most common

aircraft types is detailed in Table A4 which gives the differences between the measured noise

levels and those predicted after allowing for the validation modifications.


A.7

Aircraft Type Operation Noise Levels (SEL dB) Measured Average

INM Validated Prediction

Difference Predicted to Measured

Operation Average

Difference

Airbus A319 Arrival Rwy 04 85.3 85.5 +0.2 -0.1

Arrival Rwy 22 88.9 88.5 -0.4 Departure Rwy 04 89.8 89.4 -0.4

0.0 Departure Rwy 22 88.1 88.5 0.4

Boeing 737-300

Arrival Rwy 04 90.3 90.3 0.0 +0.1

Arrival Rwy 22 93.0 93.2 +0.2 Departure Rwy 04 91.5 90.5 -1.0

-0.15 Departure Rwy 22 89.6 90.3 +0.7

Embraer 195 Arrival Rwy 04 87.5 86.7 -0.8 -0.65

Arrival Rwy 22 90.2 89.7 -0.5 Departure Rwy 04 91.7 90.9 -0.8

-0.15 Departure Rwy 22 89.5 90.0 +0.5


Arrival Rwy 04 82.9 83.7 +0.8 +0.2

Arrival Rwy 22 86.4 86.0 -0.4 Departure Rwy 04 80.8 81.1 +0.3

+0.25 Departure Rwy 22 80.4 80.6 +0.2

Table A4 Measured and Validated Predicted Noise Levels

Table A4 shows that with the validation modifications there is good correlation between

measured and predicted noise levels with differences often around 0.5 dB or less.

Considering the average differences for arrivals and departures by each of the aircraft there is

a mixture of small over and under predictions, all of which are less than 1 dB.

The effect of the validation exercises on the contours depends both on the modifications

made and the contribution of those aircraft types to the overall noise. Obviously changes to

infrequent aircraft types are likely to have very little effect on the contours.

Comparing the results of the validation exercises in 2011 and 2010 for the most common

aircraft types operating in both years finds some changes. For the Airbus A319 the departure

factor is increased from 1.3 to 1.4. For the Let L-410 the departure factor has also increased

from 1.7 to 1.8 Conversely for the Bombardier Dash 8-Q400 the departure factor has

decreased from 1.0 to 0.8.


A.8

SUMMARY

The validation of noise contours at Belfast City Airport has been continually improved, more

recently by checking predictions against the results obtained from the Airport’s noise monitors.

This has demonstrated that without validation the standard INM assumptions would not be

accurate.

The latest contours have taken into account around 40,000 individual aircraft noise

measurements. This has identified the need to modify the standard INM assumptions for

several aircraft including the Embraer 195 and Bombardier Dash 8-Q400.

The Airport will continue to collect further detailed information from the fixed noise monitors at

Nettlefield Primary School and Kinnegar, which will be used to regularly validate future Airport

contours. That is in line with the EiP Panel’s advice on contour validation.


Appendix B

Airport Contour Validation – Tracks


B.1

AIRPORT CONTOUR VALIDATION – TRACKS INTRODUCTION

Summer noise contours have been prepared for George Best Belfast City Airport (GBBCA)

based on the actual movements during the summer period for a number of years. This has

involved the use of the Federal Aviation Administration (FAA) prediction methodology, the

Integrated Noise Model (INM).

The INM is used around the world in over 50 countries and consequently is flexible enough to

allow local circumstances to be taken into account. This includes being able to enter specific

departure routes.

As a way of checking on the accuracy of the modelling, a validation exercise has been

conducted which compares the departure tracks recorded by the Noise and Track Keeping

(NTK) system at GBBCA with those in the model which are derived from published

procedures.

PREVIOUS TRACKS

For contours to date, tracks have been derived from published procedures in the UK AIP. For

the 2010 contours, for each runway a single arrival route was assumed, but three initial

departure routes were assumed on runway 04, and one initial departure route on runway 22.

To determine the split of departures between these three routes on runway 04, the aircraft

movements were separated into small propeller, large propeller and jet aircraft. The Air Pilot

stipulates that small propeller aircraft should not commence their turn until they reach 1500ft,

large propeller aircraft until they reach 2000ft, and jet aircraft until they reach 3000ft. On

review of the aircraft used at George Best Belfast City Airport, this resulted in three departure

routes with the turns occurring at approximately 6 km, 8 km and 11 km from the start of roll.

The existing assumed tracks can be seen in Figure 1 of the report of the 2010 summer

contours Ref: A7877/DC/R01.

TRACK VALIDATION

The airport has provided information from the NTK system in the form of density plots and

track displays for single days, separately for both arrivals and departures at each runway end.

BAP have overlaid the existing tracks on the density plots to determine whether the previously

assumed routes are an accurate representation of the actual flown routes. These are shown,

along with the corrections made as a result of this validation exercise, in Figures B1 to B4.


B.2

The 54 dB LAeq,16h contour from the 2011 summer period is also shown in the Figures to give

an idea of where the routes might be influencing the contour shape and area.

For the arrivals at both runway ends, the modelled route is a straight arrival track. The actual

routes show a turn, however in both cases this is sufficiently far away from the airport that it

would have no effect on the contours. As such it is deemed that the existing assumed routes

are appropriate.

For departures on runway 04, the three existing assumed routes agree well with the actual

routes. However, there is also quite clearly a route that heads northeast which has not

previously been modelled. Looking at the track displays for single days, it appears that around

15-20% of departures on runway 04 use this route. It has been assumed that all aircraft

departing to destinations in Scotland use this route. A total of 16% of the total aircraft

movements were made to or from Scottish airports in the 2011 summer period. These were

predominantly movements by the Bombardier Dash 8-Q400 and the Saab 340.

For departures on runway 22, it is clear that the existing assumed straight route is not correct,

as the majority of the aircraft turn to the southeast around 6 km from the start of roll. There is

another turn evident around 11 km from the start of roll, however this does not appear to be

used by many aircraft and so has not been modelled.

DISPERSION

Aircraft on departure are allocated a departure route to follow. In practice, this route is not

followed precisely by all aircraft allocated to this route. The actual pattern of departing aircraft

is dispersed about the route’s main track. The degree of dispersion is normally a function of

the distance travelled by an aircraft along the route after take-off and also on the form of route.

The INM model allows this dispersion about the departure tracks to be taken into account. The

effect on the contours is to slightly widen but shorten the contours where departure noise

dominates.

When considering many departures, it is commonly found that the spread of aircraft

approximates to a "normal distribution" pattern, the shape or spread of which will vary with

distance along the route. A simplified mathematical model can be adopted to represent a

normal distribution of events, based on standard deviations. Airport noise modelling

commonly assumes that there are five "dispersed" tracks associated with each departure

route.


B.3

The allocation of movements adopted in this case to the main and sub tracks is as follows:

53.3% departures along the main track;

22.2% departures split equally along two inner sub tracks either side of the main track and offset by a distance of 1.355 standard deviations;

1.15% departures split equally along two outer sub tracks either side of the main track and offset by a distance of 2.71 standard deviations.

The existing assumed dispersion scenario for all routes is shown in Table B 1.

Distance from SOR (km)

Outer Track Displacement (m)

End of Runway 0

3.5 105

4.0 211

4.5 323

5.0 434

5.5 556

6.0 678

6.5 792

7.0 905

7.5 1007

8.0 1109

8.5 1184

9.0 1260

9.5 1324

10.0 1387

10.5 1444

11.0 and above 1500

Table B 1 Existing Assumed Dispersion (All Routes)

These dispersion assumptions have been adopted for several years at GBBCA. Now that the

new noise and radar track keeping system is fully operational, these can be checked against

the actual tracks.

For departures on runway 04, the dispersion agrees well with the existing assumed

dispersion, so no change has been made. However, for the departures on runway 22, the

aircraft are significantly more dispersed than the existing assumed dispersion once the aircraft

make the turn to the southeast. Therefore the existing assumed dispersion has been modified

and is shown in Table B 2.


B.4

Distance from SOR (km)

Outer Track Displacement (m)

End of Runway 0

3.5 105

4.0 211

4.5 323

5.0 434

5.5 556

6.0 678

6.5 792

7.0 964

7.5 1118

8.0 1272

8.5 1386

9.0 and above 1500 Table B 2 Adopted Dispersion (Runway 22 Departures)

EFFECT OF VALIDATION

A comparison has been done to check the impact of the new routes on the noise contours. As

shown in Figure B5, the 54 dB contour for 2011 is almost identical when using the new routes

compared to the previously assumed routes. The new routes would be expected to have more

impact if the contours were to grow in the future, however this would likely still be a minimal

impact.

SUMMARY

The aircraft tracks at Belfast City Airport have been validated by checking them against the

actual routes flown as shown by the Airport’s Noise and Track Keeping system. This has

demonstrated that some of the assumed routes were slightly inaccurate, but that it had a very

small effect on the noise contours.

The latest contours have taken into account around 10,000 individual aircraft tracks flown.

These have been used to identify the most common tracks used and make corrections from

the previously assumed tracks where necessary.

The Airport will continue to collect detailed track information, which will continue to be used to

validate the assumed tracks in the future.

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