What happened
On November 12, 1972, a private flight involving a Piper PA-18-150 Super-Cub, registration HB-ORZ, concluded with an excursion from the runway at Sion Airport. After departing for a private flight with a passenger, the pilot approached runway 26 under calm wind conditions. The aircraft touched down on the paved surface approximately 50 meters past the threshold at a speed of 70 mph with first-stage flaps extended.
While taxiing straight along the runway, the aircraft began a slow drift toward the left. The pilot attempted to correct the deviation using right rudder inputs but did not apply the brakes. The aircraft subsequently performed a left ground loop, causing the right wing to strike the ground before the plane came to a halt in the grass, roughly 400 meters from the runway threshold.
The investigation
Investigators examined the pilot's credentials and the aircraft's mechanical state. The pilot held a valid private pilot license but possessed limited experience, with a total of 55.09 flight hours, only 9.24 of which were on this specific aircraft type. The investigation found no evidence of health issues or prior regulatory infractions.
Regarding the aircraft, the Piper PA-18-150 Super-Cub was airworthy and properly maintained. Specifically, the tailwheel and its guide springs were in good condition, and the main tires showed appropriate wear. Weather conditions at the time of the accident included a 3-knot tailwind, a wet runway, a cloud ceiling of 300–400 meters, and visibility of 30 km.
Findings
Technical failure and weather conditions were ruled out as causes for the accident. The investigation determined that the primary cause was insufficient pilot training, as the pilot was unable to effectively correct the aircraft's trajectory following a successful landing. Additionally, the pilot's decision to release back-pressure on the control column may have reduced the effectiveness of the tailwheel's directional control on the wet runway.