Accident categories represented as Event
Sequence Diagrams (ESDs)
Alfred Roelen ([email protected])
Accident
ICAO definition:
An occurrence where :
•a person is fatally or seriously injured, or
•the aircraft sustains damage which adversely affects the
aircraft
2
Scenario clustering
Collision with ground
Collision with object
General disintegration
3
Accident types
Abrupt
manoeuvre
Personal injury
Uninhabitable
cabin
environment
(Fire/O )
Personal
injury
Collision with
ground
Accident
Loss of
control
(unrecovered)
Controlled
flight into
terrain
Aircraft
destroyed
Forced
landing
Aircraft
damaged
Mid-air
collision
Collision with
object
Collision on
ground
Structural
accident
General
disintegration
Fire/
Explosion
4
Flight phases
Cruise
Climb
Take-off
Taxi
Landing
Approach
5
Proposed scenario matrix
Taxi
Abrupt maneuver
Uninhabitable cabin
environment (fire, O2)
X
Loss of control (unrecovered)
Take-off
Climb
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Controlled flight into terrain
En-route Approach Landing
X
Forced landing
X
Mid-air collision
Collision on ground
X
Structural accident
Fire/Explosion
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
6
Scenario represented as event sequence diagram
(ESD)
Undesired
Aircraft States
Event causing deviation
from normal operation
(initiating event)
Normal
Operation
C
F (failure/accident)
B
Recovery
A
ESD Model
Generic Scenario
7
Event Sequence Diagram
8
Modelling Approach: selection of IE and PE
• Initiating Events (IE)
– deviation from normal operation
– active failures (triggering events)
• Pivotal Event (PE)
– event with possible intervention
– other causal pathway entered
– active failures
9
Accident scenario representation
From ...
To ...
10
Modelling Approach: Level of detail
• Transparency
• Limited complexity
• Minimise inter-dependencies
• ESDs can be quantified with NLR air safety database
(accident/incident/flight data)
11
ESD development steps
1) Individual accidents are analyzed and represented as a
sequence of events.
2) Accident scenarios are generalized per type of accident, IE
and flight phase.
3) Generalised scenarios are combined into one generic ESD so
that this ESD covers a class of accidents.
•
Selection of accidents/incidents: ~ past 15 years,
commercial air transport, ‘Western built’ aircraft, official
accident report available
12
Example : Loss of control accident
• Accident type: loss of control
• Flight phase: en-route/approach
• Multiple ways to loose control over the aircraft:
– different loss of control accident scenarios
13
Loss of control accident scenario initiators
• System induced
– Degraded aircraft performance, e.g. weight & balance
related, aerodynamic degradation, propulsion system
failure, ...
– Degraded flight control system, e.g. structural failure of
tail, stuck flight controls, ...
• Environment induced
– e.g. wind shear, turbulence, ...
• Crew induced
– e.g. spatial disorientation, ...
14
Example
• Accident type: Loss of control
• Flight phase: En-route/approach
• Initiating event: Propulsion system failure
15
Step 1
From accident report to
accident scenario
16
British Midlands, 737-4Y0, G-OBME,
East Midlands, January 8, 1989
17
ESD British Midland 737 G-OBME
18
Atlantic Southeast Airlines, EMB 120RT,
N256AS, Carrollton, Georgia, August 21, 1995
19
ESD ASA EMB 120RT N256AS
20
Step 2
Generalising the accident
scenarios
21
ESD British Midland 737 G-OBME
generalising
added branch through
systematic analysis and
generalising, combining
22
Step 3
From generalised specific
accident scenarios to one
generic scenario
23
Generic ESD loss of control initial climb-landing,
IE propulsion system failure
24
Results
•
33 different generic accident scenarios covering all
accident types*) and all flight phases.
*) Unlawful acts are excluded
25
Overview of all scenarios
ESD 1: Aircraft system failure
ESD 18: Single engine failure in flight
ESD 2: ATC event
ESD 19: Unstable approach
ESD 3: Aircraft handling by flight crew inappropriate
ESD 21: Aircraft weight and balance outside limits during
approach
ESD 4: Aircraft directional control related system failure
ESD 5: Incorrect configuration
ESD 6: Aircraft takes off with contaminated wing
ESD 7: Aircraft weight and balance outside limits during take-off
ESD 8: Aircraft encounters a performance decreasing wind shear after
rotation
ESD 9: Single engine failure during take-off
ESD 10: Pitch control problems
ESD 11: Fire onboard aircraft
ESD 12: Flight crew spatially disoriented
ESD 13: Flight control system failure
ESD 14: Flight crew incapacitation
ESD 15: Anti-ice/de-ice system not operating
ESD 16: Flight instrument failure
ESD 17: Aircraft encounters adverse weather
ESD 23: Aircraft encounters wind shear during approach
ESD 25: Aircraft handling by flight crew during flare
inappropriate
ESD 26: Aircraft handling by flight crew during landing roll
inappropriate
ESD 27: Aircraft directional control related system failure
during landing
ESD 28: Single engine failure during landing
ESD 29: Thrust reverser failure
ESD 30: Aircraft encounters unexpected wind
ESD 31: Aircraft are positioned on collision course
ESD 32: Incorrect presence on runway in use
ESD 33: Cracks in aircraft pressure cabin
ESD 35: CFIT
ESD 36: Collision on taxiway/apron
ESD 37: Wake vortex encounter
26
ESD 1: Aircraft system failure
27
ESD 2: Air traffic related event
28
ESD 3: Aircraft handling by flight crew
inappropriate
29
ESD 4: Aircraft directional control system failure
30
ESD 5: Incorrect configuration
31
ESD 6: Aircraft takes off with contaminated wing
32
ESD 7: Aircraft weight and balance out of limits
during take-off
33
ESD 8: Aircraft encounters a performance
decreasing windshear after rotation
34
ESD 9: Single engine failure during take-off
35
ESD 10: Pitch control problems
36
ESD 11: Fire on-board aircraft
37
ESD 12: Flight crew disoriented
38
ESD 13: Flight control system failure
39
ESD 14: Flight crew incapacitation
40
ESD 15: Anti-ice/de-ice system not operating
41
ESD 16: Flight instrument failure
42
ESD 17: Aircraft encounters adverse weather
43
ESD 18: Single engine failure in flight
44
ESD 19: Unstable approach
45
ESD 21: Aircraft weight and balance outside
limits during approach
46
ESD 23: Aircraft encounters wind-shear during
approach
47
ESD 25: Aircraft handling during flare
inappropriate
48
ESD 26: Aircraft handling during landing roll
inappropriate
49
ESD 27: Aircraft directional control related
system failure
50
ESD 28: Single engine failure during landing
51
ESD 29: Thrust reverser failure
52
ESD 30: Aircraft encounters unexpected wind
53
ESD 31: Aircraft are positioned on collision
course
54
ESD 32: Incorrect presence on runway in use
55
ESD 33: Cracks in aircraft pressure cabin
56
ESD 35: CFIT
57
ESD 36: Collision on taxiway/apron
Ground collision
imminent
ATC fails to resolve
the conflict
Flight crew fails to
resolve the conflict
Ground crew fails
to resolve the
conflict
Aircraft
damaged
yes
no
Aircraft
continues
taxi
Aircraft
continues
taxi
Aircraft
continues
taxi
58
ESD 37: Wake vortex encounter
Wake vortex
encounter
yes
no
Flight crew fails to
maintain control
Personal injury
Collision
with
ground
Personal
injury
Aircraft
continues
flight
59