Ka 4 Rhönlerche II incident during winch launch training at Porrentruy airfield
On August 27, 1972, an Alexander Schleicher Ka 4 Rhönlerche II was involved in an incident at Porrentruy airfield in Switzerland during a winch launch training exercise. The flight instructor and student pilot were conducting a simulated cable break when the instructor took control but did not notice the spoilers were deployed. This oversight led to a rapid descent and collision with the ground and an obstacle. Both the instructor and student sustained serious injuries, and the glider was significantly damaged. The official report confirmed the cause as a lack of attention by the instructor.
- Winch launch training: During a winch launch training flight at Porrentruy, an instructor and student in a Rhönlerche II conducted a simulated cable-break exercise shortly after takeoff.
- Simulated cable release: At about 60–80 meters height, the instructor released the winch cable to simulate a cable break.
- Student descent setup: The student correctly lowered the nose, deployed spoilers, and announced an intention to land straight ahead.
- Spoilers left extended: The instructor, intending to demonstrate a circuit back to the launch point, did not notice that the spoilers remained extended when he took control.
- Turn back with spoilers: Unaware of the spoilers being out, the instructor pushed the nose to gain speed and initiated a right turn to attempt a circuit back, but the glider’s speed did not increase and the descent rate remained high.
- Tight low-altitude turn: Concerned about obstacles and trying to regain the runway, the instructor tightened the right turn at low height, further increasing bank to avoid a wooden hut and a glider trailer until the right wing struck the ground.
- Crash - serious injury: After the right wing contacted the ground, the glider pivoted, struck the trailer with its tail, and came to rest after a half-turn, seriously injuring both occupants and heavily damaging the glider.