Ka 6 crash on Diablerets due to collision with rock face in poor visibility

On July 14, 1983, a Ka 6 CR glider piloted by a Swiss national crashed into the northwest face of the Diablerets in Switzerland. The pilot was participating in an alpine gliding camp and took off for a long-duration flight. The aircraft was reported missing when it did not return by 1800 local time, prompting a search operation. The wreckage was discovered the following day at an altitude between 2500 and 2900 meters. The pilot sustained fatal injuries, and the glider was destroyed. The collision with the rock face occurred as the pilot likely flew into clouds without the necessary training.

1. Aerotow cross-country: The pilot departed Zweisimmen at 11:26 local on an aerotow for a long alpine soaring flight in Ka 6 CR HB-766.
2. Marginal mountain weather: In the Diablerets area the afternoon weather featured a cloud base around 2700–3000 m with partial heavy cloud, rotor cloud and descending cloud fragments, and nearby peaks often in cloud.
3. No cloud-flying rating: The pilot was licensed only for VFR gliding and had no authorization or documented training for cloud (IFR) flight, although the aircraft itself was approved for cloud flying.
4. Entered cloud near terrain: While ridge-soaring near the Diablerets around 16:45, the glider did not avoid descending cloud fragments and very probably entered cloud in close proximity to the northwest rock face.
5. Continued near clouds: Witnesses observed the glider at times in or behind clouds and noted that it did not deviate to avoid cloud fragments, suggesting the pilot continued flight close to or within cloud despite limited visibility.
6. Loss of visual reference: Once in cloud near steep terrain, the pilot likely lost external visual references and, despite the turn coordinator being powered, was not able to maintain safe separation from the mountainside.
7. Crash - fatal: The glider impacted the steep northwest rock face of the Diablerets at about 2900 m, was completely destroyed, and the pilot sustained fatal injuries.