What happened
On the morning of October 5, 1969, a pilot departed from Sion, Switzerland, for a series of recreational flights in the Grande-Dixence region. After completing two earlier flights with different passengers, the pilot embarked on a third flight at 12:41, carrying one passenger. The aircraft, a Piper J 3 C with registration HB-OVD, was flying a route from Sion toward Dixence.
Around 13:10, while flying at a low altitude near the Cheilon glacier, witnesses observed the aircraft suddenly stall on its right wing. The plane pulled up vertically before entering a spin. The aircraft completed three rotations in the spin before impacting the ground near the edge of the glacier. The impact resulted in two fatalities: the passenger died instantly, and the pilot succumbed to his injuries two days later. The aircraft was destroyed.
The investigation
The investigation, conducted in collaboration with the Valais cantonal police, examined the aircraft's mechanical condition, the pilot's experience, and the environmental factors. Investigators found that the Piper J 3 C was well-maintained, with all necessary certificates and recent inspections in order. While an unusual 7.1 kg weight was found attached to the fuselage structure, it was determined that the center of gravity remained within permissible limits and likely did not contribute to the accident.
Meteorological data indicated clear skies and good visibility at the time of the occurrence, with no significant turbulence reported in the immediate vicinity. Witnesses noted that the aircraft appeared to be flying at a low altitude and a relatively low airspeed prior to the stall.
Findings
- The primary cause of the accident was an exceeded angle of attack.
- This aerodynamic stall was the result of inappropriate mountain flying techniques.
- The aircraft entered a spin at an altitude too low to allow the pilot to recover to a normal flight attitude.