What happened
On 16 July 2019, an Aeroprakt A2/LS Foxbat Supersport 600, registration G-CHSY, was performing a private flight from Otherton Airfield in Staffordshire. The aircraft, which had recently undergone an annual inspection, was operated by the pilot accompanied by one passenger.
During the takeoff roll, the pilot utilized the first stage of flaps. Shortly after becoming airborne, the left wing dropped at an altitude of approximately 100 feet. In an attempt to recover, the pilot requested the passenger to retract the flaps. As the aircraft continued to lose altitude, the pilot reduced engine power and applied full right rudder. The aircraft reached a maximum height of only about 70 feet before striking a crop field at the end of the runway. The impact occurred with the right wing low and the engine power reduced to idle. Both the pilot and the passenger sustained serious injuries, and the aircraft was destroyed.
The investigation
The AAIB examined the aircraft's Dynon Skyview avionics system, successfully downloading flight data from the accident. This data revealed that while the pilot believed they were maintaining speeds between Vx and Vy, the actual indicated airspeed at liftoff was only approximately 30 kt, fluctuating between 26 kt and 32 kt. The investigation also reviewed the pilot's weight and balance calculations, which confirmed the takeoff mass of 567 kg was within the allowable limits.
Furthermore, the investigators assessed the pitot/static system, which showed no obvious physical anomalies upon visual inspection. The investigation also considered the pilot's report of a pre-flight altitude discrepancy between the Skyview display and standby instruments.
Findings
- The aircraft became airborne at an airspeed very close to the stall speed for its configuration.
- The retraction of flaps during the wing drop increased the stall speed, making recovery impossible at the low altitude attained.
- The Skyview system displayed an incorrect, higher airspeed than was actually being achieved, leading the pilot to believe the aircraft was performing within safe parameters.