What happened
On 8 April 2025, a Hoffmann H36 Dimona, registration G-CIMC, was conducting an introductory flight at Darley Moor Airfield in Derbyshire. Shortly after departing from the runway, the aircraft began to yaw to the right and struggled to maintain a stable climb or sufficient airspeed. Eyewitnesses observed the aircraft "wallowing," with the nose pitching up and down in a manner consistent with an aerodynamic stall. At an altitude of approximately 100-15 and 150 ft, the aircraft rolled sharply to the right and fell in a steep, nose-down attitude. The impact resulted in two fatalities, involving both the pilot and the passenger.
The investigation
The AAIB investigation examined the aircraft's mechanical condition, flight data, and weight and balance records. Technical examinations of the engine and flight controls found no evidence of mechanical or electrical failure that would have caused a loss of power or control. Analysis of the aircraft's weight and balance revealed that the aircraft had taken off approximately 35 kg above its maximum allowable mass. This was due to a combination of factors, including an incorrect payload figure in a recent weighing report and the lack of a formal process to verify passenger weights.
An anthropometric study was also conducted to assess the cockpit environment. The study found that because of the passenger's size, there was a possibility that the throttle control could be inadvertently moved by the passenger's leg, though no evidence confirmed this occurred during the flight. The investigation also noted that the pilot's daily inspection book had not been signed for the day of the accident.
Findings
- The aircraft was unable to maintain a safe climb profile following takeoff.
- The aircraft was operating above its maximum approved takeoff mass.
- The passenger's mass exceeded the maximum weight limit for the aircraft seat.
- An error in the aircraft's weighing report led to an incorrect understanding of the maximum available payload.
- There was no formalised procedure at the club for weighing passengers on an ad hoc basis.
Safety action
Following the accident, the British Gliding Association (BGA) issued guidance to its member clubs regarding the oversight of introductory flights and the importance of thorough flight preparation. The BGA also intends to instruct inspectors to ensure all weight limitations, including non-lifting parts, are clearly identified in weighing reports. The operating club has updated its booking process to require online data capture and weight declarations from customers prior to scheduling flights, and will now verify these weights at the airfield.