1964 Piper PA-18 Super Cub accident at Planura, Linthal (HB-OWA)

Overview and aircraft details On 18 May 1964, a Piper PA-18 Super Cub, registration HB-OWA, was destroyed when it struck a snow cliff near the Planurahütte on the Hüfifirn in Linthal, Glarus. The aircraft was a 1963 Piper Super Cub PA 18 “150,” serial number 7980, powered by a 150 hp Lycoming engine. It was equipped with hydraulically operated “Federal” skis and was owned and operated by the pilot. The aircraft had been imported into Switzerland in August 1963 and had accumulated 88 hours 56 minutes in 184 flights by the time of the accident. No technical defects were found before the accident. ## Flight and accident sequence The pilot, born in 1913, and a passenger, born in 1931, departed Zürich-Kloten at 10:25 for a wood transport to the Tierberghütte. After landing there at 11:10, they departed at 11:45 for the Planurahütte. The pilot had made four landings on the glacier the previous day and performed only one reconnaissance circuit before approaching the usual landing site north of the hut. During the approach, he touched down on a takeoff track instead of the landing track to its left. The takeoff track led directly into a snow cliff. Although the pilot attempted to turn left and increase power, the right ski slid over the ridge, and the aircraft rolled twice down a steep snow slope for about 50 m, coming to rest tail-first in soft snow. Both occupants left the wreckage uninjured. ## Investigation findings The investigation concluded that the accident was caused by the pilot confusing the landing track with the adjacent takeoff track, which led into the snow cliff. The curved approach terrain, limited visibility of the landing site, and a wind from the left rear were considered to have contributed to the confusion. The accident occurred during the critical transition from landing to climb-out, a phase that heavily occupied the pilot. After touching down on the wrong track, the pilot had only limited ability to prevent the crash. The aircraft’s airframe was beyond repair and was later sunk into a glacier crevasse. The engine showed a bent crankshaft, and the radio was damaged by leaked hydraulic oil. Total damage was estimated at about CHF 60,000. No third-party damage occurred.