What happened
On 16 June 2022, a Diamond DA42-NG, registration F-HIMY, was conducting an instructional flight at Courchelar mountain airfield. The flight, involving a pilot and an instructor, was intended to renew the pilot's access approval for the mountain aerodrome.
During the final approach to runway 22, the aircraft encountered a strong downdraft. In response, the instructor took control of the aircraft, increased engine power, and retracted the flaps from the landing position to the approach position to reduce drag. Despite these adjustments, the aircraft touched down approximately 170 meters from the runway threshold with an average ground speed of about 105 knots, aided by a 9-knot tailwind component.
Upon touchdown, the instructor attempted to brake, but the aircraft could not be stopped on the 18.66% slope. The aircraft continued down the runway, eventually running off the end and colliding with a bank. The aircraft was destroyed in the accident.
The investigation
The BEA investigation utilized engine computer (ECU) data, surveillance camera footage, and webcam recordings from the airfield. The investigators analyzed the aircraft's flight path, power settings, and flap configuration during the final thirty seconds of the approach. The investigation also reviewed the meteorological conditions, noting an unstable air mass and moderate gusts at the time of the accident. Additionally, the investigators examined the flight experience of both the pilot and the instructor, specifically regarding recent mountain landings in twin-engine aircraft.
Findings
- The primary cause of the runway overrun was a non-stabilized final approach characterized by significant variations in power, flight path, and flap configuration in the final seconds before touchdown.
- The decision to land with the flaps in the approach configuration, rather than the landing configuration, contributed to an increased landing distance.
- The instructor's limited recent experience performing mountain landings in twin-engine aircraft was a contributing factor.
- Environmental conditions, including a tailwind and thermal-induced gusts, further complicated the landing execution.