What happened
On August 13, 1973, a Piper Super-Cub PA-18-150, registration HB-ORK, departed from the MutthornHütte glacier landing site for a commercial flight toward Bern. The aircraft was carrying the pilot and one passenger. During the flight, the passenger requested to be dropped off in the vicinity of Häutligen, and the pilot agreed to land on a meadow owned by the passenger.
After performing two reconnaissance passes over the area, the pilot determined that the primary intended landing site was occupied by active harvesting operations. Consequently, the pilot decided to land on an alternative, slightly higher meadow measuring approximately 213 meters in length. The pilot approached this field without performing the required reconnaissance. To clear a high-voltage power line positioned perpendicularly to the landing direction, the pilot had to increase engine power during the approach.
The aircraft touched down approximately 120 meters after crossing the power lines. Due to the rising terrain, the remaining runway length before reaching a treeline was only about 93 meters. The pilot attempted to steer the aircraft to the right to avoid the trees, but the maneuver was unsuccessful. At 17:40, the left wing struck a fir tree, causing the aircraft to veer left and come to a stop among the trees with the engine still running.
The investigation
The investigation examined the pilot's experience, the aircraft's condition, and the circumstances of the approach. The pilot was a highly experienced glacier pilot with over 6,200 total flight hours, including approximately 5,000 hours in this specific aircraft type. No medical issues were identified at the time of the accident. While the pilot admitted to consuming some alcohol prior to the flight, blood tests conducted later that evening showed an alcohol level below 0.05 per mille.
Technical inspections of the HB-ORK revealed no pre-existing mechanical defects, and the aircraft's weight and center of gravity were within limits. The investigation also noted that the pilot's flight operations manual prohibited alcohol consumption eight hours prior to duty and throughout the flight period.
Findings
- The pilot failed to sufficiently scout the chosen landing site.
- Inadequate reconnaissance prevented the pilot from realizing that clearing the power line required a high approach angle, which significantly shortened the available landing distance.
- The remaining 93-meter rollout was insufficient to stop the aircraft before reaching the forest edge.
- The aircraft sustained heavy damage, though there were no injuries to the occupants.