What happened
On January 5, 1971, a Champion Challenger (registration HB-UAU) was performing a mountain landing at the Männlichen site in the Bernese Oberland. The flight originated from Linth, and the pilot had previously coordinated with the landing site keeper, who had warned of icy undulations on the western side of the prepared landing area but indicated that the eastern, rolled snow strip remained viable.
During the approach, the pilot identified the uneven terrain but determined that an approach into the western runway strip was possible without encountering visible ice waves. The aircraft touched down in a three-point position on the western strip. Approximately 25 meters into the landing roll, the left ski struck a bump with significant force, causing it to be torn away from the aircraft. As the aircraft briefly lifted and then descended again, the exposed landing gear wheel sank into the snow. The resulting high impact load caused the left landing gear to buckle.
There were no injuries to the pilot or the passenger during the incident, though the aircraft suffered heavy damage.
The investigation
The investigation examined the aircraft's airworthiness, the pilot's qualifications, and the environmental conditions at the time of the accident. The Champion Challenger was found to be in an airworthy condition with no pre-existing mechanical defects. The pilot held valid licenses specifically including endorsements for mountain landings and specialized training in mountain landing techniques. Weather conditions at the time were clear with visibility exceeding 10 km and light winds.
Findings
- The primary cause of the accident was the overstressing of the landing gear due to landing on uneven terrain.
- The pilot's decision to land on the western portion of the field, despite the known presence of undulations, led to the initial impact that dislodged the ski.