Mid-air collision between ASW 20L and DG-500 near Walliser Wispile, Switzerland

On July 29, 2003, an Alexander Schleicher ASW 20L and a DG Flugzeugbau DG-500/22 ELAN collided mid-air near Walliser Wispile, Switzerland. Both aircraft were engaged in an alpine soaring flight during a training camp. The collision occurred at approximately 2700 meters altitude, resulting in the destruction of both gliders. Two pilots survived by parachuting to safety, while the third pilot tragically died in the incident. The official investigation determined that the collision was caused by the pilots seeing each other too late.

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.