What happened
On March 15, 1969, a pilot was conducting a transition flight in a WLM-1 glider under the supervision of an instructor at the Colombier airfield. This flight was intended to introduce the pilot to the more advanced characteristics of the aircraft following a period of several months without flight activity due to military service.
After a successful takeoff via a Piper PA 18 tug, the pilot completed a circuit and released from the tow at an altitude of approximately 500 meters. While attempting to execute a maneuver near the airfield, the pilot pitched the nose up by roughly 13 degrees to reduce airspeed. During this descent, the glider reached a critical speed, stalled, and entered a right-hand spin. The aircraft completed several rotations before impacting the ground, resulting in the destruction of the aircraft and grievous injuries to the pilot.
The investigation
Investigators examined the pilot's recent flight history, noting that while the pilot held a valid license, they had not flown since September 1968. The investigation also reviewed the aircraft's maintenance records, which showed the WLM-1, registration HB-551, had undergone a complete overhaul in 1968 and was in good airworthy condition.
The inquiry focused on the specific maneuvers being performed at the time of the stall. Investigators looked into whether the pilot was attempting a commanded stall maneuver or preparing for holding patterns, and whether the use of flaps was consistent with the instructor's specific pre-flight instructions.