What happened
On March 11, 2005, two gliders were conducting competition training flights near Argentière la Bessée, France. The first aircraft, a Rolladen Schneider LS8 with registration D-0032, had departed from Château Arnoux Saint-Auban earlier that morning as part of a three-glider group. The second aircraft, a Schleier ASW19 registered D-8881, departed from the same airfield shortly after, flying in a separate group of three gliders.
At approximately 13:23 UTC, while maneuvering near the Tête du Puy at an altitude of roughly 2,590 meters, the two aircraft collided. The left wingtip of the LS8 struck the canopy of the ASW19, causing the latter to lose its elevator. The ASW19 entered a steep dive and crashed into a steep, snow-covered slope. The pilot of the ASW19 was killed in the impact. The pilot of the LS8 managed to maintain control of the aircraft and successfully performed an emergency landing at the Mont Dauphin Saint-Crépin airfield approximately eighteen minutes later.
The investigation
The investigation focused on the flight paths and the visibility of the aircraft during the approach to the ridge. GPS data from both aircraft were analyzed to reconstruct the trajectories, which revealed that the two gliders were flying on nearly opposite headings in a straight line. The investigators also examined the effectiveness of the anti-collision markings on both aircraft, noting that while both had red reflective bands, these were only visible from specific angles.
Furthermore, the investigation reviewed the communication protocols used by the two different flight groups. Although a common inter-group radio frequency was available, it was not being utilized by the pilots at the time of the accident. The investigators also looked at the environmental conditions, noting that the background of snow-covered mountains provided very low contrast for the white and colored aircraft.