What happened
On August 11, 1963, a pilot conducting a training flight near Saanen, Switzerland, experienced a significant loss of altitude while attempting a triangular route between Saanenmöser, Col du Pillon, and Château-d’Oex. After reaching a peak altitude of approximately 2300 meters, the pilot encountered a sharp descent while flying back toward Gstaad, eventually dropping to an altitude of only 300 to 400 meters above the valley floor.
To avoid the risk of flying over the populated area of Gstaad at such a low altitude, the pilot opted for a precautionary landing on a 70-meter-long meadow at the southern edge of the village. During the final approach, the Ka-8 aircraft, registration HB-752, struck four wires of a transverse electrical power line approximately 8 meters above the ground. The impact tore the left wing from its attachment point, causing the aircraft to rotate 180 degrees and strike the ground nose-first.
The investigation
The investigation examined the flight conditions, the visibility of the obstacles, and the pilot's decision-making process. Investigators noted that the pilot was participating in a gliding camp and had relatively limited flight experience at the time. The weather was characterized by clear skies and light thermals, though local winds were present, including a 20-knot wind from the south.
Findings
- The pilot was forced into an unplanned landing due to a continuous loss of altitude.
- The electrical cables were extremely difficult to detect because they featured dark, brownish-gray rubber insulation that blended into the landscape.
- The visibility of the wires was further obscured by nearby trees and the lack of visible insulators on the support rods.
- The pilot failed to identify the four wires crossing the landing path during the final approach.
- The landing site was short and irregularly shaped, and a 10 m/sec tailwind likely would have made a safe landing difficult even without the cables.