What happened
On 15 August 2022, a Rolladen Schneider LS4 glider, registration F-COKE, was performing a local flight near Aillon-le-jeune. The pilot, operating under the authority of the Centre Savoyard de Vol à Voile Alpin (CSVVA), initiated a winch takeoff from Chambéry – Challes-les-Eaux airport at approximately 15:45.
After reaching an altitude of 1,350 m, the pilot initially headed toward Peney mountain. Due to a lack of thermal activity, the pilot returned toward the airport before finding new lift that brought the aircraft to 1,600 m. The pilot then transitioned to slope soaring along the north-facing west slopes of Bonvillard mountain. After performing a U-turn to head south, the glider passed over the Col de la Verne pass (1,513 m). During this maneuver, the wing of the glider struck treetops on the ridge near the summit of Mont de la Croix. The impact destabilized the aircraft, causing it to collide with further vegetation and the ground. The pilot sustained injuries, and the glider was destroyed.
The investigation
The BEA examined the flight path using statements from the pilot and data from the Open Glider Network (OGN). The investigation reviewed the aircraft's wreckage, noting that the fuselage was found in a nearly vertical, 3/4 inverted position. The collision with trees had torn off the wings and tail fin and broken the canopy.
Investigators also analyzed the meteorological conditions, noting a northwesterly wind of 10 knots and a temperature of 26°C. While the forecast indicated an uplift ceiling of 2,100 m, the actual thermal development was limited. The investigation also reviewed the local flight regulations established by the CSVVA, which define specific altitude floors and lateral limits for pilots flying under the "Pass" qualification.