What happened
On May 22, 2017, a Cessna 172M, registered HB-CEO, was conducting a training flight for mountain instructor qualification. The crew, consisting of a pilot and an instructor, had previously completed several takeoffs and landings at the Courchevel and Méribel Robert Merloz altiports before proceeding to the Saint-Jean-d’Arves altisurface.
During the approach, the aircraft was slightly below the glide path and positioned to the right of the runway centerline. Upon touchdown of the main landing gear, the aircraft experienced a sudden deceleration. The nose gear subsequently sank into the soft ground and broke. This caused the aircraft to pitch forward violently, resulting in the plane flipping onto its back. There were no fatalities or injuries reported, but the aircraft sustained heavy damage.
The investigation
The investigation focused on the runway conditions and the aircraft's touchdown parameters. The altisurface at Saint-Jean-d’Arves is an unpaved strip measuring 330 by 50 meters with a 15% slope. Investigators noted that the surface appeared soft, with the presence of shallow tractor tracks near the runway edge and grass color suggesting recent moisture or softness. Meteorological conditions at the time were reported as CAVOK with light, variable winds from the north.
Findings
- The primary cause of the accident was the nose gear penetrating the soft, unpaved surface during the landing roll.
- The aircraft was slightly below the intended glide slope and off-center at the moment of touchdown.
- The structural failure of the nose gear led to the forward pitch-over and subsequent inversion of the aircraft.