Collision en vol entre ASW 20L et DG-500 près de Walliser Wispile, Suisse

Le 29 juillet 2003, un Alexander Schleicher ASW 20L et un DG Flugzeugbau DG-500/22 ELAN sont entrés en collision en vol près de Walliser Wispile, en Suisse. Les deux planeurs participaient à un vol de vol à voile alpin lors d'un camp d'entraînement. La collision s'est produite à environ 2700 mètres d'altitude, entraînant la destruction des deux planeurs. Deux pilotes ont survécu en sautant en parachute, tandis que le troisième pilote est malheureusement décédé dans l'incident. L'enquête officielle a déterminé que la collision a été causée par le fait que les pilotes se sont vus trop tard.

1. Cruise alpine soaring: Both gliders were in straight-and-level alpine soaring flight around 2700 m MSL in the Walliser Wispile area after departing from Zweisimmen (DG-500) and Saanen (ASW 20L).
2. Multiple gliders nearby: The ASW 20L pilot was aware that at least four other gliders were operating in the same area, increasing traffic complexity without any specific separation or coordination.
3. Inadequate lookout: Despite both DG-500 pilots sharing lookout duties and the ASW 20L pilot scanning the area, neither crew detected the opposing glider in time to avoid conflict.
4. Opposing traffic sighted late: While cruising on reciprocal tracks, the ASW 20L pilot suddenly saw the red nose of the DG-500 very close ahead and the DG-500 rear-seat pilot heard a shout and then saw the other glider on collision course.
5. Last-moment evasive inputs: Both pilots attempted to evade— the ASW 20L pilot pulled the stick left and the DG-500 front-seat pilot likely banked left and pushed to pass underneath— but with insufficient time and separation.
6. Frontal mid-air impact: The two gliders collided nearly head-on, causing major structural damage including separation and severe damage to wings and cockpits.
7. Crash - fatal: Both gliders were destroyed, the ASW 20L pilot and DG-500 rear-seat pilot bailed out and survived with broken feet, and the DG-500 front-seat pilot was unable to escape and was fatally injured in the subsequent crash.