What happened
On August 22, 1970, a Piper PA-18-150 Super Cub, registration HB-OYK, departed Reichenbach with the intention of retrieving a passenger from the Mutthorn hut area on the Kanderfirn glacier. The pilot, flying solo, was carrying various supplies including beverages and fuel.
Upon reaching the upper glacier, the pilot found that weather conditions had deteriorated significantly since the morning, with fog obscuring the target destination. Although a clear patch was visible approximately 50 meters south of the hut, the pilot attempted to fly below the cloud base to navigate the glacier. While following the terrain, the pilot lost all forward visual references. Trapped between fog on the left and steep terrain on the right, the pilot attempted an emergency landing on the north slope of the Petersgrat. During the impact, the aircraft's landing gear was destroyed, and the plane overturned. The pilot escaped the wreckage without injury.
The investigation
The investigation examined the pilot's flight experience, the aircraft's mechanical condition, and the prevailing meteorological circumstances. The aircraft, equipped with both wheels and skis, was found to be in a valid state of airworthiness with no mechanical deficiencies identified. The investigation also reviewed the pilot's history, noting extensive experience in mountain flying, though also noting previous incidents involving landing gear issues and flight regulation infractions.
Findings
- The primary cause of the accident was that the pilot attempted to complete the flight despite insufficient visibility and cloud ceilings in the approach sector.
- The pilot's desire to fulfill the commitment to the passenger led to an engagement in an extremely hazardous situation.
- Diffuse lighting conditions in the mountains further complicated visual navigation.
- The pilot's decision to fly under the cloud layer was a high-risk maneuver that ultimately led to the loss of visual references.