What happened
On February 13, 2011, a Jodel D140, registration F-BMFT, was performing a training flight at the Saint Jean d’Arves altisurface. The flight was part of a mountain qualification program specifically focused on ski operations. The aircraft was occupied by an instructor, a student pilot, and one passenger.
Upon landing on the snow-covered surface, the pilot attempted a turn at the end of the runway to prepare for takeoff. During this maneuver, the aircraft began to slide approximately 15 meters due to the slippery conditions of the slope, which featured a slight cross-slope that had not been identified by the pilot. As the aircraft drifted, the instructor reduced engine power and directed the student and passenger to evacuate the aircraft while it was still sliding. The aircraft eventually struck wooden stakes that served as a barrier to prevent further descent down a steeper slope. This impact caused the fabric on the underside of the wing to tear.
The investigation
The investigation focused on the environmental conditions and the crew's response to the excursion. Investigators established that the snow on the landing strip was packed and highly slippery. The instructor, who did not hold a mechanic's qualification, performed a temporary repair on the torn fabric using adhesive tape before attempting to fly the aircraft back to the departure airfield.
Findings
- The primary cause of the excursion was the crew's failure to account for the slippery nature of the sloped, snow-covered surface during the turn.
- The aircraft sustained minor damage to the wing fabric following the collision with wooden stakes.
- The decision to perform a temporary repair with adhesive tape without a professional structural inspection could have left potential structural damage undetected.