On January 8, 1989, British Midland Flight 92 crashed while attempting an emergency landing near Kegworth, England. An investigation found that a fan blade broke off in one of the engines, causing damage and a fire. The crew shut down the wrong engine and diverted to land, but the remaining engine failed during descent. The Cognitive Reliability and Error Analysis Method (CREAM) was developed to analyze accidents from both retrospective and prospective views by considering the context in which errors occurred. When applied to the Kegworth disaster, CREAM identified lack of aircraft knowledge, inadequate training, design flaws, and high workload as contributing factors in the crew's errors.

1. CREAM
ANALYSIS OF
THE KEGWORTH
AIR DISASTER
ROSS APTED

2. KEGWORTH AIR DISASTER
Scene of the disaster – wreckage on M1 motorway near Kegworth

3. 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)

4. 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.
1. Smoke flooded into the cabin. Captain shut down the
engine on the right.
1. Smell of smoke and vibrations reduced.
1. Crew diverted to Midlands Airport. Left engine completely
failed during the descent of the emergency landing

5. COGNITIVE RELIABILITY AND ERROR
ANALYSIS METHOD (CREAM)

6. CREAM - COGNITIVE
RELIABILITY AND ERROR
ANALYSIS METHOD
(Hollnagel E. , Cognitive Reliability and Error Analysis Method., 1998)
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

7. 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.

8. 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
After context has been
Crew collaboration quality
established analysis
can begin

9. COMMON PERFORMANCE
CONDITIONS

10. 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.

11. 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)

12. 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.

13. 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)

14. COMMON PERFORMANCE
CONDITIONS –
KEGWORTH

15. RETROSPECTIVE
ANALYSIS - KEGWORTH

16. RETROSPECTIVE
ANALYSIS - KEGWORTH

17. 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.

18. 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.

19. 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.

20. 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)

21. REFERENCES
Air 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.