Investigation Summary
The accident involved a brand-new Boeing 737-400, a variant the pilots had very little experience with. When a fan blade in the left engine suffered a fatigue fracture due to 'blade flutter' (a vibratory instability), smoke entered the cockpit. The Captain, drawing on his experience with older 737 variants where the right engine supplied air to the flight deck, assumed the right engine was the source of the smoke. This was reinforced when the First Officer mistakenly identified the right engine as the problem. Crucially, when they throttled back the healthy right engine, the autothrottle reduced power to the surging left engine as well, which caused the vibrations to stop and the smoke to clear. This 'false feedback' convinced the crew they had correctly identified the failed engine. They proceeded to shut down the healthy right engine and attempted an emergency landing on the remaining, damaged left engine, which failed entirely during the final approach.
Final Conclusions
The AAIB concluded that the primary cause was the crew's incorrect identification of the failed engine, leading to the shutdown of the healthy engine. Contributing factors included the crew's lack of familiarity with the 737-400's engine instrument displays (which used digital LED scales rather than mechanical pointers), the misleading cessation of symptoms when the healthy engine was throttled back, and a breakdown in CRM where cabin crew and passengers who saw flames from the left engine did not communicate this to the cockpit.
Photographic Evidence (1)
Video Analysis
The Kegworth Air Disaster | British Midland flight 92 — A detailed look at the 1989 accident where a Boeing 737-400 crashed near the M1 motorway after the pilots mistakenly shut down the wrong engine following a mechanical failure.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
Had 763 hours on other 737 models; hours on type refers strictly to the 737-400 variant.
First Officer
Had 192 hours on other 737 models; hours on type refers strictly to the 737-400 variant.
Systems & Failure Modes
CFM56-3C1 Engine
The left engine suffered a fan blade fracture due to flutter, a phenomenon not previously encountered during testing of this engine variant.
Airborne Vibration Monitor (AVM)
The AVM for the left engine showed maximum vibration, but the pilots were not accustomed to trusting the new electronic displays.
Air Conditioning System (ACS)
Design changes in the 737-400 meant smoke from the left engine could reach the flight deck, contradicting the pilots' mental model of older 737s.
Interesting Facts
- 01The aircraft was a Boeing 737-400, which had been in service for only 521 airframe hours.
- 02The pilots had only 76 combined hours of experience on the 737-400 series at the time of the crash.
- 03Passengers and cabin crew saw flames coming from the left engine, but this information was never relayed to the pilots.
- 04The 737-400 air conditioning system takes air from both engines for the cabin, unlike older models the pilots were used to.
- 05The crash resulted in the first major study of the 'brace position,' leading to international safety standard revisions.
Safety Actions & Advisories
Brace Position Research
Extensive research into passenger injuries led to the creation of the International Board for Research into Aircraft Crash Events (IBRACE) and revised brace position standards.
Engine Testing Requirements
The discovery of fan blade flutter led to more rigorous testing requirements for new engine variants under high-power flight conditions.
CRM Training
The accident highlighted the need for cabin crew to proactively report technical observations (like engine flames) to the flight deck.
Known Controversies & Unanswered Questions
Dismissal of Flight Crew
Reference ↗Captain Hunt and First Officer McClelland were dismissed by British Midland following the AAIB report. Hunt later criticized the decision, suggesting the pilots were an 'easy option' and that the investigation should have focused more on why the mistakes were made. McClelland eventually received an out-of-court settlement for unfair dismissal.
Initial Cross-Wiring Suspicions
Reference ↗Early in the investigation, there was significant concern that the engine fire warning lights or sensors might have been cross-wired, leading the pilots to the wrong engine. However, the AAIB established that the wiring was correctly connected.