What happened
On July 2, 1999, at approximately 14:20, a Glaser-Dirks DG 800 B motor glider, registration D-KCDG, was participating in a local flight near Bessans, France. The aircraft had departed from Fayence earlier that morning, traveling toward the Aosta Valley alongside another glider.
While flying west of the Charbonnel peak at an altitude of approximately 3,220 meters, the pilot of the accompanying glider observed the D-KHDG entering a low-speed spiral. The aircraft subsequently entered a spin. After completing approximately three rotations, the motor glider exited the spin but struck a steep mountainside. The impact resulted in the death of the pilot and the total destruction of the aircraft.
The investigation
The investigation focused on the flight sequence and the aerodynamic state of the aircraft prior to impact. Evidence from a witness in the accompanying aircraft indicated that the pilot of the D-KCDG had previously communicated via radio that they had encountered and countered the onset of an autorotation. Meteorological conditions at the time of the accident included visibility of 15 to 25 km, good thermals without significant turbulence, and winds from the west-northwest at 20 to 25 knots.
Findings
The investigation established that the primary cause of the accident was a stall at low altitude, which led to the development of the spin and the subsequent collision with the terrain.