What happened
On 16 August 2022, a Schemps Hirth - Nimbus 2 glider, registration F-CPAT, was performing a local flight near Oyonnax, France. After taking off via a towed launch, the pilot navigated toward the Bauges mountain range. Upon reaching the south-west slope of the Semnoz mountain, the aircraft began a progressive loss of altitude.
For approximately 30 minutes, the pilot performed maneuvers over the mountain slope. As the altitude dropped to roughly 450 meters above the valley, the pilot moved away from the slope toward the valley floor, likely in preparation for an off-field landing. At an altitude of approximately 160 meters, the pilot executed a series of spiral maneuvers in the valley without successfully gaining height. Following a northward flight path, the glider entered a right-hand turn while descending and collided with trees in a wooded area in the Gruffy commune. The impact resulted in one fatality and the destruction of the aircraft.
The investigation
Investigators utilized GNSS data from the onboard computer to reconstruct the flight path. The examination of the wreckage confirmed that the glider struck the treetops with forward horizontal speed, causing the wings and tail unit to detach. The investigation found no evidence of mechanical or technical failure; the landing gear was extended, and the flight controls were functional prior to the impact.
Meteorological analysis indicated that while some thermal activity was present on the eastern slopes of the mountain, the south-west slopes were unlikely to provide lift during that time of day. Furthermore, the investigation noted that the pilot's position in the valley, following the maneuvers, had moved away from the most suitable landing fields and nearby aerodromes.