1972 Piper PA-18-180 Accident at Glacier du Trient (HB-OPV)

Flight Details and Accident Sequence On Saturday, May 13, 1972, a pilot departed from Lausanne-La Blécherette aerodrome at 09:45 local time in a Piper PA-18-180, registration HB-OPV, with his wife as a passenger. The flight was a private operation intended to include a landing on the Glacier du Trient. The pilot had received weather information by telephone from Geneva, reporting good visibility and winds of 10–15 knots from the southwest sector, with temperatures at 10,000 feet between -5°C and -10°C. Additionally, a pilot returning from the Mont-Rose confirmed good conditions in the Trient area and advised a “lancé” (bounced) landing on the upper part of the glacier due to snow conditions. The pilot made three overflights of the selected landing site at the top of the glacier before landing at 10:25. The aircraft left a track in the snow estimated by the pilot to be 150 meters long. At the end of the landing roll, fresh snow prevented the aircraft from turning fully into a takeoff position; it came to rest at an angle of approximately 45 degrees relative to the landing axis. With the assistance of his wife, the pilot aligned the aircraft and observed that the fresh snow layer was 30 to 40 cm deep. The pilot performed a normal pre-takeoff check, running the engine, and left the mixture setting in the same position as during approach, considering it optimal for takeoff at that altitude (3,000 m MSL). The first takeoff attempt was made heading north, with the engine accelerating normally and the flaps initially in the takeoff position. After a certain distance, the pilot extended the flaps to maximum, but the aircraft did not become airborne. The pilot aborted the attempt after 300 to 400 meters and exited the aircraft to assess the remaining available distance on foot. He estimated that the fresh snow layer was only 5 to 7 cm deep at that point and believed a renewed attempt could be made without significant risk. After re-checking the skis, he moved the aircraft approximately 150 meters to gain distance on the nearly horizontal glacier. At the start of the second attempt, 500 meters were available. As the aircraft reached the séracs, it crossed a first crevasse approximately 7 meters wide; the rear ski struck a sérac, causing the aircraft to tip into a crevasse, where it came to rest 30 meters lower at 11:20.