What happened
On 11 September 2017, a Rotorsport UK Calidus gyroplane, registration G-CIYU, was performing a private takeoff from Runway 22 at RAF Scampton, Lincolnshire. After the pilot pre-rotated the rotor and released the brakes, the aircraft accelerated rapidly down the asphalt runway. At a groundspeed of approximately 40-50 mph, the aircraft experienced a sudden, rapid nose-up pitch.
As the aircraft pitched upward, it rolled onto its left side. The retreating rotor blade struck the runway surface, causing the aircraft to roll further and the nose to drop. The impact resulted in the separation of the nose landing gear and caused the rotor to strike the propeller, scattering debris across the runway. The gyroplane eventually slid on its side for about 50 metres before coming to a halt.
While the pilot and passenger were uninjured, they found themselves unable to exit the aircraft because the weight of the gyroplane was pressing against the canopy. Although an emergency hammer was available, the pilot did not attempt to break the plexiglass, instead waiting for the airfield's Rescue and Fire Fighting Service. Firefighters eventually arrived and righted the aircraft, which allowed the occupants to open the canopy and escape safely.
The investigation
The AAIB examined video footage of the takeoff, which revealed that the rotor disc did not tilt back during the initial takeoff roll. This lack of tilt meant the necessary drag force was absent, leading to an unusually high acceleration. The investigation established that the pilot likely failed to tilt the rotor back before releasing the brakes, potentially due to a subconscious reversion to fixed-wing takeoff techniques learned from years of flying conventional aircraft.
Upon reviewing the footage, the pilot realised that the rotor was not rotating at a sufficient speed to generate the lift required to support the aircraft's weight during the pitch-up maneuver. The investigation also noted that the aircraft was operating on a damp, downhill-sloping asphalt runway, which contributed to the rapid acceleration.
Findings
- The primary cause of the accident was inappropriate control movement during the takeoff phase.
- The pilot failed to tilt the rotor disc back prior to releasing the brakes, which prevented the necessary drag for proper autorotation and led to excessive acceleration.
- The pilot's extensive experience in fixed-wing aircraft may have caused a subconscious reliance on different takeoff procedures, often referred to as "muscle memory."
- The weight of the aircraft on the canopy prevented the occupants from opening the door immediately following the impact.