A Royal Air Force Service Inquiry has concluded that debris which had sat inside the carburettor of a Battle of Britain Memorial Flight (BBMF) Spitfire for decades was very likely to have caused the loss of engine power behind the fatal crash near RAF Coningsby on 25 May 2024. The Ministry of Defence published the final report on 1 October 2026, UK Aviation News reported.
The accident killed Squadron Leader Mark Long, 43, who was flying Spitfire MK356 alone when the aircraft came down shortly after taking off from RAF Coningsby in Lincolnshire. The aircraft was destroyed.
What happened on 25 May 2024
According to the report, MK356 took off at approximately 13:16 as Squadron Leader Long began a planned sortie involving a series of flypasts and an aerial display. During the early part of the flight the aircraft suffered a significant reduction in engine performance. Engine performance information and witness accounts examined by the inquiry were consistent with fuel starvation.
Investigators examined the aircraft's Rolls-Royce Merlin engine and its carburettor in detail. They found debris inside the carburettor that had partially obstructed the lean metering jet, restricting the amount of fuel reaching the engine. The resulting mixture was too lean for the Merlin to produce the power required, and the inquiry concluded that the debris was very likely the causal factor that prevented the engine from producing enough thrust to maintain flight.
Chemical analysis of the material indicated it had been present inside the carburettor for decades.
Conflicting maintenance publications
The inquiry also looked at the maintenance information for the carburettor. It identified inconsistencies between different maintenance publications, which created uncertainty about how far the component should be dismantled, inspected and cleaned. The report says this ambiguity very likely reduced the opportunity for the material to be found before the accident flight.
The findings do not attribute the accident to a single action or individual. The inquiry was convened to establish the circumstances and identify lessons to improve safety, and the report says it is intended to support learning within Defence rather than apportion blame.
26 recommendations
The report makes 26 safety recommendations. They cover maintenance documentation and records, inspection and maintenance procedures, pilot training and the management of emergencies in historic aircraft.
The inquiry also examined survivability. It found that the aircraft's restraint system was critical to pilot survivability, but concluded that aspects of the restraint system and the cockpit design were likely to have aggravated the consequences of the impact. It recommends that changes to improve pilot protection be considered, while recognising the particular difficulty of modifying historic aircraft without affecting their authenticity and airworthiness.
That tension sits at the heart of the report. The BBMF flies irreplaceable Second World War aircraft at displays and commemorations, and the inquiry's recommendations look beyond the immediate engine failure to how such aircraft can be maintained and operated safely while preserving their heritage.
An experienced display pilot
Squadron Leader Long was an experienced RAF pilot in his fourth season with the BBMF. He had flown the Tucano, Hawk and Harrier GR7/9 before joining the Typhoon Force at RAF Coningsby, where he served as the RAF Typhoon display pilot and also carried out Quick Reaction Alert and overseas air-policing duties.
After the accident the RAF described him as a highly regarded pilot and colleague who was passionate about aviation and the Battle of Britain Memorial Flight.
The report brings formal findings to an accident that remained under investigation for more than two years. The Ministry of Defence said it had published the final report to inform the military chain of command and the public of the inquiry's findings and its recommendations to improve defence safety.
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