What happened
On January 29, 1964, at approximately 11:39 CET, a Piper Super Cub Pa-18A, registration HB-OPE, departed from Crans for Sion as part of a glacier landing training course. The aircraft, equipped with metal skis for the winter conditions, began its takeoff roll toward the west. The engine initially performed well, and the aircraft became airborne after roughly 130 meters.
Shortly after reaching an altitude of only a few meters, the aircraft suffered an unexpected loss of power. The pilot attempted to manage the situation, but the aircraft could not maintain flight and crossed a depression at the end of the runway. The aircraft bounced approximately 100 meters before the tips of the skis struck an embankment at the edge of a road. The impact caused the landing gear to collapse, the propeller to be torn off, and the aircraft to come to a halt after a partial turn. The pilot sustained minor injuries, but the aircraft was 60% destroyed.
The investigation
The investigation examined the engine, carburetor, and fuel lines, finding no mechanical abnormalities. Investigators noted that the pilot had performed standard pre-flight checks, including a carburetor heat test, which showed a typical RPM drop. The weather conditions at the time of the accident involved a transition between cold air masses, with temperatures at 2°C below freezing and a recent layer of snow covering the ground.
Findings
- The primary cause of the accident was a loss of engine power occurring immediately after takeoff.
- The loss of power was likely caused by carburetor icing due to the prevailing meteorological conditions.
- The aircraft was operating in a flight training capacity for the Valais Section of the Swiss Aero Club.