What happened
On the morning of July 4, 1964, a pilot underwent transition training on a Champion 7 GCB, registration HB-UAT, at Kloten airfield. Following the training, the pilot embarked on a flight with a passenger, visiting Ascona, Locarno, Agựo, and Samedan. Despite reports of thunderstorms developing along the northern side of the Alps, the pilot attempted to return to Kloten via the Julier Pass.
After passing Bivio, the pilot was forced to turn back due to a thunderstorm discharging north of Lake Marmorerasee. While navigating the valley, the aircraft's altitude dropped significantly. Near a ridge west of the Julier Pass summit, the pilot initiated a steep left-hand turn at a low altitude of approximately 30 meters above ground and a low airspeed. During this maneuver, the aircraft entered an aerodynamic stall, resulting in a vertical impact on an alpine pasture. The pilot died instantly, and the passenger succumbed to severe injuries one week later.
The investigation
The investigation examined the pilot's flight history, the aircraft's technical condition, and the meteorological environment. The pilot had recently obtained his private pilot license and had only completed approximately 99 flight hours, with very limited experience in the Champion 7 GCB and only three previous Alpine crossings.
Technical examination of the wreckage of HB-UAT showed no evidence of mechanical failure or engine malfunction. The aircraft's weight and balance were found to be within permissible limits. Meteorological data confirmed that while the weather was deteriorating due to thunderstorms, the primary issue was the aircraft's flight path and maneuverability within the terrain.