CREAM ANALYSIS OF THE KEGWORTH AIR DISASTERROSS APTED

Scene of the disaster – wreckage on M1 motorway near Kegworth

KEGWORTH AIR DISASTER

WHAT HAPPENED

On 8th January 1989 British midland flight 92 crashed while undertaking an emergency landing.

Crashed site : M1 embankment near the village of Kegworth.

The Boeing 737 -400 aircraft was severely damaged 79 of the of the 126 people aboard the plane survived.

An investigation was carried out by the Air Accidents Investigation Branch (AAIB). (Air Accidents Investigation Branch, 1989)

EVENTS OF CRASH

1. Moments after reaching cruising attitude fan blade broke off causing decrease in power and increase in vibrations. This caused the left engine to produced a jet of flames.

2. Smoke flooded into the cabin. Captain shut down the engine on the right.

3. Smell of smoke and vibrations reduced.

4. Crew diverted to Midlands Airport. Left engine completely failed during the descent of the emergency landing

COGNITIVE RELIABILITY AND ERROR ANALYSIS METHOD (CREAM)

CREAM - COGNITIVE RELIABILITY AND ERROR ANALYSIS METHOD  

Background:

Developed by Erik Hollnagel in 1998

Cognitive system engineering approach

design of human-machine systems accounting for factors of the environment in which the system exists.

Key idea:

Cognitive modeling of human performance for accident analysis or performance predictions

(Hollnagel E. , Cognitive Reliability and Error Analysis Method., 1998)

HOW CAN IT BE USED

CREAM is a bi – directional analysis method.

Retrospective analysis – the analysis of error. Used for accident analysis.

Prospective analysis – predicting possible error. Used for accident prediction.

COMMON PERFORMANCE CONDITIONS

Humans action can be correct or incorrect but also occur within the context of situation.

Context can greatly effect an persons actions. Cream breaks down context into 9 criteria.

Adequacy of organization

Working conditions

Adequacy of MMI and operational support

Availability of procedures/ plans

Number of simultaneous goals

Available time

Time of day (circadian rhythm)

Adequacy of training and expertise

Crew collaboration quality

After context has been established analysis can begin

COMMON PERFORMANCE CONDITIONS

ANALYSIS

CREAM defines error as follows:

Phenotype – An error that is a physical action that can be measured and observed.

Genotype – The errors possible cause influenced by context.

These boundaries greatly reduce the inconsistency between different analysts.

ANALYSIS

Cream describes how errors happen through the following terminology:

Antecedent – the cause of the error.

Consequent – the effect of the error.

Each antecedent may have one to * consequent and each consequent may have one to * antecedent.

Using a table of varies antecedents and consequents an analysis of the accident can be built.

(Serwy, Rantanen, & Hollnagel)

MAN-TECHNOLOGY-ORGANIZATION (MTO) TRIAD

The contextual antecedents and consequents are split into three categories:

Man – physical and cognitive limitations of person.

Technology – technological failure

Organization – failure of the organization in which the situation exists.

At each stage of the analysis there are several options to proceeded, due to the context stage some of these option are more likely.

simplifies analysis processes.

HOW TO DO CREAM

The CREAM technique can be used for both retrospective and prospective analysis. Here is how to use it:

1) Identify the Common Performance Conditions, under 'CPC’

2) Start with a genotype "Error Mode" (with retrospective) or a phenotype "MTO triad" (with prospective) under 'Workspace’

3) For each step, select a Specfic Consequent to better explain the step.

4) For retrospective analysis, if there is enough information to select a specific antecedent, then do so. The analysis stops for that branch.

5) Continue with each step of the analysis, exploring all the likely paths as shown in the left panel of the Workspace.

(Serwy, Rantanen, & Hollnagel)

COMMON PERFORMANCE CONDITIONS –KEGWORTH

RETROSPECTIVE ANALYSIS - KEGWORTH

RETROSPECTIVE ANALYSIS - KEGWORTH

EVALUATION

Specific antecedent were found to be:

• Lack of knowledge of the aircraft

• Inadequate training of the flight crew

• Design failure of the aircraft( no visibility of engines)

• Competing tasks – cabin workload to high.

ADVANTAGES OF CREAM

Allows for the context of the accident to be taken into account. Shows how the context in which people work effect there actions.

Can effectively do both Retrospective and Prospective analysis. Only need to learn once as they used the same simple principles.

A good structure that keeps inconsistency between different analyst low.

DISADVANTAGES OF CREAM

Resource hungry, requires a long period of time to complete.

Need to have a good level of exposure accident analysis in particular the human factors.

No guidance on how the errors you have found can be reduced.

USEFUL RESOURCES

Software tool for CREAM analysis.

http://www.ews.uiuc.edu/~serwy/cream/v0.6.1/

Evaluation of software(tells you how to use it)

REFERENCESAir Accidents Investigation Branch. (1989). Report on the Accident to Boeing 737-400 G-OBME near Kegworth, Leicesterhire on 8 Janury 1989. Aldershot: Air Accidents Investigation Branch.

Hollnagel, E. (1998). Cognitive Reliability and Error Analysis Method. Oxford: Elsevier Science Ltd.

Serwy, R. D., Rantanen, E. M., & Hollnagel, E. (n.d.). How to do CREAM. Retrieved August 3, 2012, from Cognitive Reliability Error Analysis Method Web Demonstration Version 0.6: http://www.ews.uiuc.edu/~serwy/cream/v0.6.1/

Smith, D. (2000). On a wing and a prayer? Exploring the human components of technological failure. Syst. Res. , 543–559.