Summary
On 5 October 1969, a Piper J 3 C aircraft, registration HB-OVD, crashed near Cabane des Dix in the Valais region of Switzerland. The passenger died on impact, and the pilot died two days later from injuries. The aircraft was destroyed.
Investigation
The investigation was conducted by the Swiss Federal Commission for Aircraft Accident Investigation in collaboration with the Valais cantonal police. The enquiry was closed on 24 August 1970.
Aircraft and Pilot Information
The aircraft was a Piper J 3 C with a Continental C-90-14F engine of 90 hp, owned and operated by the Aéro-Club de Suisse, section Valais. It had accumulated approximately 4851 flight hours. The pilot held a valid private pilot license issued on 13 June 1963, with a total flight experience of 140.04 hours, primarily on Piper Cub variants. His last medical examination on 13 March 1969 found him fit.
Circumstances of the Accident
On the morning of 5 October 1969, the pilot departed Sion at 1014 h with a female passenger for a first pleasure flight over the Dixence region, landing at 1114 h. A second flight with another passenger took place from 1125 h to 1225 h. After refueling, the pilot departed again at 1241 h with a male passenger, who sat in the front seat (with the control stick removed). The intended route was Sion – Dixence – Sion. Around 1310 h, witnesses observed the aircraft flying at low altitude from the Grande-Dixence artificial lake toward Mont Blanc de Cheilon. As it flew over the glacier moraine, the aircraft abruptly stalled on the right wing, pitched up, entered a spin, and crashed after three turns.
Wreckage and Post-Accident Examination
The wreckage was located at the edge of the Cheilon glacier at an altitude of approximately 2950 m. The fuselage was bent and crushed forward; the wings were deformed. The fuel selector was open, the magneto switch was in position 1+2, the stabilizer trim was neutral, and the altimeter was set to 1023 mb, indicating 9600 feet. No pre-impact mechanical failure was found. Two lead bars weighing 7.1 kg total were found attached to the rear fuselage structure; their origin and purpose were not determined.
Probable Cause
The accident was due to exceeding the permissible angle of attack, resulting from inadequate mountain flying technique, followed by a spin at an altitude too low to recover normal flight attitude.