Incidente con Ka 4 Rhönlerche II durante entrenamiento de lanzamiento con torno en el aeródromo de Porrentruy
El 27 de agosto de 1972, un Alexander Schleicher Ka 4 Rhönlerche II estuvo involucrado en un incidente en el aeródromo de Porrentruy en Suiza durante un ejercicio de entrenamiento de lanzamiento con torno. El instructor de vuelo y el alumno piloto realizaban una simulación de rotura de cable cuando el instructor tomó el control pero no se dio cuenta de que los aerofrenos estaban desplegados. Este descuido llevó a un rápido descenso y colisión con el suelo y un obstáculo. Tanto el instructor como el alumno sufrieron heridas graves, y el planeador resultó significativamente dañado. El informe oficial confirmó que la causa fue la falta de atención del 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.