What happened
On July 23, 1970, a K8B glider, registration HB-958, was engaged in a cross-country flight attempt near the Weissenstein region in Switzerland. During the flight, the pilot was maneuvering near the ridge between Hasenmatt and Geissflue. While flying at a low airspeed, the pilot executed an abrupt left-hand turn to avoid a perceived collision risk with another glider. This maneuver caused the aircraft to enter a left-hand spin. Due to the extremely low altitude, the pilot was unable to recover the aircraft before it struck a wooded area on the steep northern slope of the ridge. The impact resulted in one serious injury to the pilot and the total destruction of the aircraft.
The investigation
Investigators examined the wreckage of the K8B and analyzed flight data from the onboard barograph. The wreckage examination confirmed that all primary flight controls, including the ailerons, elevators, rudder, and trim, were properly connected and secured. There was no evidence of pre-existing mechanical failures or technical defects. The barograph data indicated that the aircraft experienced a sudden loss of altitude of approximately 65 meters during the final moments of the flight. The investigation also reviewed the aircraft's weight and balance, noting that the center of gravity was positioned toward the rear of the permitted range.