What happened
On June 2, 1970, during a flight training session at the Bellechasse airfield in Switzerland, a student pilot was operating a K 8 B glider, registration HB-831. The flight was part of a training camp organized by the "Broyé" gliding group.
During the second solo flight of the day, the pilot was performing a landing approach. While on the final approach at approximately 85 km/h, the pilot initially deployed the airbrakes to a mid-position. As the aircraft began to lose altitude rapidly due to the prevailing wind conditions, the pilot fully retracted the airbasting.
At an altitude of roughly 20 meters, the pilot attempted to deploy the airbrakes again. This action coincided with an inadvertent forward movement of the control stick. The aircraft entered a steep 45-degree dive, striking the ground approximately 170 meters before the runway threshold. The impact caused the glider to bounce, enter a right-hand turn, and eventually undergo a ground loop, resulting in the aircraft turning approximately 180 degrees. The pilot sustained no injuries, though the aircraft suffered severe damage.
The investigation
An investigation was launched on June 3, 1970. Investigators examined the aircraft, which had been moved to a hangar, and found no mechanical defects. The aircraft's maintenance records showed it had been well-maintained, with a successful official inspection conducted just one week prior to the accident.
Physical evidence on the ground, including tracks in a wheat field, corroborated the instructor's account of the flight path. The investigation also reviewed the pilot's training progress, noting that while the student was considered serious and progressing normally, this was only his second flight in this specific aircraft model.
Findings
- The primary cause of the accident was the improper manipulation of the elevator controls while the pilot was operating an aircraft with which he was not yet fully familiar.
- The pilot likely momentarily diverted his attention from the flight path to locate the airbrake handle within the cockpit during a critical low-altitude phase.
- The pilot's attempt to re-deploy the airbrakes at a very low altitude, combined with an accidental forward pitch of the stick, created an unrecoverable descent.
- The aircraft's structural damage included a deformed lower fuselage, broken landing skid, and significant damage to the wing spars and fabric.