What happened
On June 21, 1969, a pilot operating a Mucha Standard glider, registration HB-644, performed an unplanned off-field landing near Lyss. The pilot had departed from Courtelary airfield with the intention of conducting a cloud flight, but decided during the flight to attempt a landing in a field near his home. This specific location had been scouted by the pilot previously, though he had never performed an off-field landing before.
During the approach, the pilot found himself too high on the final leg. To correct his altitude, he initiated a 360-degree left-hand turn. During this maneuver, the aircraft lost sufficient airspeed and entered a stall. The glider struck the ground at approximately 14:10, resulting in serious injuries to the pilot and the total destruction of the aircraft.
The investigation
The investigation examined the pilot's flight experience, the aircraft's maintenance history, and the environmental conditions at the time of the accident. The Mucha Standard was found to be airworthy and properly maintained, with weight and balance within limits. Investigators also reviewed the pilot's decision-making process regarding the selection of the landing site and the execution of the landing maneuver.
Findings
- The pilot chose an unsuitable landing site based on convenience rather than safety; the field was located on a slope that dropped away from the approach path and was bordered by trees and shrubs.
- The pilot failed to adequately prepare for the off-field landing, specifically neglecting to account for the terrain's descent during his approach.
- The primary cause of the accident was the underspeed during the turning maneuver, which led to the aerodynamic stall.
- The pilot's attempt to lose altitude through a steep turn, rather than using more appropriate techniques like a slip, directly contributed to the loss of control.