What happened
On December 17, 2003, a Schleicher ASK 16 motor glider, registration HB-2002, was performing a private VFR flight from Bern-Belp airport. Shortly after departing on runway 14, at an altitude of approximately 30 meters and about 600 meters before the end of the runway, the cockpit canopy suddenly opened and swung to the right.
In an attempt to secure the canopy, the pilot unbuckled his seatbelt to reach upward. To allow the pilot to focus on closing and locking the canopy, the pilot instructed a passenger, who had no prior flight experience, to take control of the aircraft. While the pilot worked to re-secure the canopy, the aircraft entered a series of vertical oscillations between 10 and 40 meters above the ground. The aircraft eventually pitched up at a 60-degree angle at the end of the runway before banking sharply to the left. The aircraft struck the ground with its landing gear, subsequently hitting a wooden fence, which caused significant damage to the wings and propeller. Both occupants escaped the wreckage without injury.
The investigation
Investigators examined the cockpit canopy's locking mechanism and found no evidence of mechanical failure or external force that would have caused it to open spontaneously. The mechanism, which requires significant force to properly align and lock the bolts, was found to be functional. The investigation also reviewed the flight controls, which were found to be operating normally. Meteorological conditions at the time of the accident were favorable, with clear visibility and calm winds.
Findings
- The primary cause of the accident was the loss of control resulting from the pilot's attempt to close the cockpit canopy during the takeoff phase.
- The transfer of flight controls to an inexperienced passenger contributed to the inability to maintain a stable flight path.
- The pilot was preoccupied with the canopy mechanism, which prevented the timely recognition of the developing uncontrolled flight state.
- There was no evidence that the canopy unlocked due to a mechanical defect.