A 1935 bi-plane that crashed killing its pilot and passenger shortly after take-off from Compton Abbas airfield near Shaftesbury had reported a ‘rough running engine’.
The accident in August 2017 happened as the plane attempted to return to the airfield. The 64-year-old pilot was a former jumbo jet captain and his aircraft was well-maintained and used regularly for experience flights. The Air Accident Investigation Branch report explained what happened on the morning of the flight:
The flight was intended to be an introductory flight for the passenger, which the operator referred to as an “air experience flight”, and was the aircraft’s first flight of the day. The pilot arrived at the airfield and was seen to carry out a full pre-flight inspection of the aircraft including checking the fuel tank quantity, which was full, and performing a water check of a fuel sample.
The passenger arrived at the airfield at about 0730 hrs and completed the required documentation before receiving a briefing on the aircraft and associated safety matters. He was then dressed in flying clothing, including a flight suit, leather gloves, flying jacket, goggles, and a helmet with a built-in headset and microphone.
The passenger was taken to the aircraft and assisted into the front cockpit by a member of the ground crew who ensured his safety harness was secure and that the headset lead was connected. He also pointed out the flying controls and other items to remain clear of. The pilot then occupied the rear seat. His normal habit was to carry out his general and safety brief of the passenger.
The flight was to last for 30 minutes and was to overfly Shaftesbury, followed by the Steam Fair at Blandford Forum, before returning to the airfield.
The weather at the time of the accident was not recorded but included light and variable wind, clear skies and good visibility with a small amount of fog in the valley to the north of the airfield .
Another member of the ground crew was responsible for starting the engine by hand swinging the propeller. The normal procedure of priming the fuel line and cylinders was followed and on the second swing of the propeller the engine briefly ran backwards.
With the possibility of an over-primed engine, the propeller was turned backwards several rotations in accordance with the operating manual and a second attempt to start was made but was unsuccessful. On the third start cycle, at the second attempt, the engine started and was warmed up before the magneto checks were performed by the pilot, which sounded normal with no rough running.
Pic: AAIB report
The wheel chocks were removed and the aircraft taxied to the threshold of Runway 08. It was seen to accelerate along the runway before becoming airborne at about the 300 m marker. At that point, the engine was heard to misfire but the aircraft continued to climb.
Witness recollections indicate that the aircraft probably made a left turn to the north, which was the intended direction after departure. The airfield does not record radio transmissions on its air/ground frequency but the operator heard the pilot transmit in an apparently calm voice that he had a “rough running engine” and was making a 180o turn to land on Runway 26. The radio operator responded that the wind was light and northerly. The engine could not be heard by witnesses at the airfield.
The perceived direction of turn differed between witnesses, but during the turn or when rolling out of it, the aircraft appeared to be slow and in one witness’ description, it appeared slow and became unstable before a wing dropped sharply and the aircraft descended rapidly in a turn which they thought was to the right. One witness thought that as it departed the airfield, it pulled up sharply before making a right turn and descending steeply towards the ground. A witness approximately 1,500 m south of the accident site heard and then saw the aircraft climbing slowly at low airspeed, with the engine “sounding awful and misfiring” before it descended “corkscrewing down”.
A flying instructor, who had been speaking to the accident pilot earlier, was next to the radio operator when he heard the transmission indicating engine trouble. He looked out of the window and located the aircraft heading north approximately 1 to 2 nm from the airfield at about 500 feet above airfield elevation. He saw it make a gentle, descending left turn onto a right base leg for Runway 26 and when above some high trees at the eastern end of the field, at about twice their height and some 200 m beyond them, the nose pitched sharply down and the aircraft rolled to the left in a steep descending turn. Shortly afterwards a column of smoke was seen.
Two witnesses at a farm approximately 350 m from the accident site heard the aircraft takeoff. One saw it briefly above trees before losing sight of it behind a barn, after which they heard the engine stop. Driving towards the scene they could see smoke and on arrival at the wreckage they were unable to assist the occupants.
The aircraft had struck the surface of a crop field in a steep nose-down attitude and caught fire. The airfield fire and rescue service attended the scene and controlled the fire using foam and dry powder. Both the pilot and passenger were fatally injured.
The air accident investigation branch said the exact cause of the engine problem and the reason for the nose dive couldn’t be determined.