1) On January 8, 1989, British Midland Flight 92 crashed near Kegworth, England while attempting an emergency landing. An investigation found the flight crew shut down the wrong engine in response to a technical failure in the left engine. 2) On October 7, 2008, Qantas Flight 72 experienced uncommanded pitch downs due to incorrect data from an Air Data Inertial Reference Unit. The accident highlighted issues with relying solely on computer systems without adequate redundancy or human oversight. 3) A June 2012 AAIB bulletin reported a serious incident involving a Boeing 757 that lost power to its left electrical bus and instruments. The incident was traced to a corroded crimp terminal and demonstrated the AA

1. AVIATION
ACCIDENTS
AND
INCIDENTS
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. AAIB INVESTIGATION
Events of the crash
1. During the ascent of the aircraft to its cruising altitude of
35,000 feet metal fatigue occurred on the fan blades in
the left engine.
Due to the engine
design not being able to
withstand vibrations caused
by operation above 25, 000
feet and a high power
setting.
Boeing 737–400 Engine

5. AAIB INVESTIGATION
2. Fan blade broke off causing decrease in power and
increase in vibrations. This caused the left engine to
produced a jet of flames.
3. Smoke flooded into the cabin. Captain shut down the
engine on the right.
4. Smell of smoke and vibrations reduced.
5. Crew diverted to Midlands Airport. Left engine completely
failed during the descent of the emergency landing

6. AAIB INVESTIGATION
Causes of the Crash
The flight crew shut down the right engine(which was
functioning correctly – could have sustained aircraft)
In response to the left engine being damaged(blade
fracture.)
The left engine then completely failed due to increases stress
during approach to land.
The wrong engine was shut down.
Primary cause: Human error
Secondary cause: technical failure

7. CONTRIBUTING
FACTORS
Inadequate knowledge of the aircraft
Flight crew observed smoke in the cabin.
Believed they could not trust the Vibration sensors. Was true
of the old Boeing 737 but not the new 737-400.
Indicates the state of the engines.
Fell back on general knowledge of aircraft which was wrong.
Thought that bleed air(pressure and heating) was taken from
the right engine.
In fact the air conditioning systems utilized both engines in
the new model.

8. BOEING 737 (OLD)
Right engine
Key
- bleed air via air
conditioning

9. BOEING 737-400
(NEW)
Right engine Left engine
Key
- bleed air via air
conditioning

10. CONTRIBUTING
FACTORS
In adequate training
The combination of violent engine vibrations and the smell of
smoke while climbing to covered attitude was not covered in
training.
Two separate protocols existed for each event but not in
conjunction.
No simulation training for engine failure of this kind, or what to
do if the situations fall out of bounds of standard procedures.
Differences in the Boeing 737 and 737-400 were not adequately
taught.

11. WHY THE MISTAKE
WAS NOT FOUND
By chance the the smoke dissipated and the vibrations
reduced – this was actually due to standard procedure
reducing fuel flow to both the engines.
Pilots did not communicate with the cabin crew who had
visual confirmation of which engine was damaged.
Immediate division to Midlands airport create a high cabin
workload this resulted in incorrect review procedure after the
right engine was shut down.

12. Insufficient
knowledge
of aircraft
Right In
Crash
engine was adequate
shut down training
Improper
Left engine design
failed testing

13. ACADEMIC
LITERATURE
On a Wing and a Prayer? Exploring the Human Components of
Technological Failure
(Smith, 2000)
Key points
Exploring the role of human error in complex technical systems.
Case study Kegworth
Thesis – Import to not only focus on individual but social and
managerial framework in which the exist.
Conclusion – With fly – by –wire system on the rise it is ever
more import to look at the organization as a
whole and not just focus on individual aspects.

14. QANTAS FLIGHT 72
Qantas A330-303 - the type of aircraft that the incident occurred on

15. WHAT HAPPENED
On the 7th October 2008 Qantas Flight 72 made an
emergency landing due to in flight accident.
A series of in uncommand pitch down maneuvers were
initiated resulting in crew and passenger injury.
An investigation was carried out by The Australian Transport
Safety Bureau (ATSB).
(Australian Transport Safety Bureau )

16. ATSB INVESTIGATION
Events of the accident
1. At cruising altitude one of the Air Data Inertial Reference
Unit stated to providing incorrect values know as spikes
to flight systems.
Air Data Inertial Reference Unit(ADIRU) –provides air
data such as air speed, altitude and angle of attack the
pilots flight instruments.
2. The autopilot disconnect an warning were triggered.
3. Aircraft rapidly pitched down unprompted. Due to the
flight control primary computer the angle of attack spike.

17. ATSB INVESTIGATION
4. Sudden forces cause severe injuries to the aircrafts
occupants.
5. A second pitch down occurred moments later.
6. Pilots switch to manual operation a sent a Mayday
distress.
7. Flight was diverted to Learmonth, Western Australia

18. ATSB INVESTIGATION
Cause of the accident
flight control primary computer
Is a “full-authority” flight control system. Get its flight data
from the ADIRU’s. 3 ADIRU for error resistance and
redundancy.
If all 3 ADIRU are consistent the and average of ADIRU1 and
ADIRU2 is used.
If ADIRU1 or ADIRU2 are not consistent then a memorized
value is used for 1.2s.
Fault occurred when there was multiple spikes 1.2s apart.

19. ATSB INVESTIGATION
ADIRU data-spike
ADIRU entered a failure mode in which it was sending invalid
data to flight system but marking it as being valid.
No warning that the unit had failed was trigged.
Hardware bug – the CPU module of the unit would inexpiably
combined the parameter for value with the label for another
parameter.

20. AIRBUS VS BOEING
Airbus philosophy - safety will be reduced by removing
human error
= giving the computer more control.
Boeing philosophy - safety will be reduced by removing the
complexities between the interactions of humans and
technology.
= give pilot unlimited control but make it easier to interact
with the computer.

21. AAIB BULLETIN- INCIDENT
Boeing 747- the type of aircraft that the incident occurred on

22. SERIOUS INCIDENT
Serious incident involving a Boeing 757-21B found in the
June 2012 bulletin.
(Air Accidents Investigation Branch, 2012)
AAIB Bulletin – A monthly notice of accidents and serous
incident.
What happened:
The Aircraft lost power to its left AC electrical bus, causing
the failure many flight instruments.

23. BACKGROUND
1. Mid-flight the “L AC BUS OFF” and “L GEN OFF” warning
lights triggered indicating a power failure.
2. Multiple flight instruments failed.
3. Commander carried out the drill for power loss in the left
generator.
4. Bus reset and power temporally restored
5. Power went off again this time accompanied with thin
smoke on flight deck.
6. MAYDAY was sent and aircraft was diverted to nearest
airport.
Only effect on passengers was that they had to
catch a new flight.

24. AAIB INVESTIGATION
Found that be a corroded crimp
terminal at the D1114J connector
which is part of the left power
generation system.
Procedure
Split into previous and post incident
maintenance actions
Still focuses on crew actions Broken D1114j connector
Standardized format for bulletins – focus on primary sources of
information little root cause analysis.

25. REFERENCES
Air Accidents Investigation Branch. (2012). June 2012
Bulletin. Aldershot: Air Accidents Investigation Branch.
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.
Australian Transport Safety Bureau. (2008). In-flight upset
154 km west of Learmonth, WA 7 October 2008 VH-QPA
Airbus A330-303. Canberra: Australian Transport Safety
Bureau.
Smith, D. (2000). On a wing and a prayer? Exploring the
human components of technological failure. Syst. Res. , 543–
559.