What happened
On August 27, 1972, a flight instructor and a student pilot were conducting a training exercise at the Porrentruy airfield using a Rhönlerche II glider, registration HB-674. The purpose of the flight was to demonstrate a simulated cable break during a winch launch.
Upon reaching an altitude of approximately 60 to 80 meters, the instructor disconnected the cable. The student pilot responded to the simulated emergency by establishing a descent, deploying the spoilers, and preparing for a landing directly ahead. While the student's actions were correct, the instructor took control of the aircraft to attempt a circuit maneuver to return to the starting point.
Crucially, the instructor did not notice that the spoilers were extended. As the aircraft entered a right-hand turn, the descent rate remained high and the airspeed failed to increase. While attempting to avoid a wooden shed and a glider trailer near the ground, the instructor increased the bank angle. This caused the right wing to strike the ground, leading the glider to pivot and strike a trailer with its tail section before coming to a halt.
The investigation
The investigation focused on the flight crew's actions and the aircraft's configuration. The instructor was a qualified flight instructor with 521 total flight hours, while the student pilot had approximately 11 hours of experience. Both pilots were found to be in good health and had clean regulatory records.
Technical inspections confirmed that the Rhönlerche II was airworthy and that no mechanical failures contributed to the event. Meteorological conditions at the time of the accident were favorable and did not impact the flight. The investigation also noted that the instructor had previously performed similar maneuvers where he returned to the starting point to avoid the need for ground handling of the glider.
Findings
- The student pilot performed the correct procedures following the simulated cable break.
- The instructor failed to observe that the spoilers had been deployed by the student.
- The lack of attention by the instructor regarding the aircraft's configuration led to an unachievable flight path for the intended circuit.
- The impact with the ground and obstacles was caused by the instructor tightening the turn to reach the runway without realizing the high rate of descent caused by the spoilers.