Accidente del ASK 13 durante vuelo de entrenamiento cerca de Muottas Muragl, Suiza

El 23 de julio de 1969, un Alexander Schleicher ASK 13 se estrelló durante un vuelo de entrenamiento cerca de Muottas Muragl, Suiza. La aeronave entró en pérdida de sustentación cerca de la ladera de la montaña y cayó en espiral al suelo, resultando en la muerte del instructor y del alumno a bordo. El planeador quedó completamente destruido al impactar. El incidente ocurrió durante un campamento de entrenamiento organizado por Weser-Fluggemeinschaft, donde el ASK 13 se utilizaba para vuelos de instrucción.

1. Winch launch training: During a training flight launched by winch, the ASK 13 with instructor in the rear seat and student in front climbed from Samedan toward Muottas Muragl to fly ridge/soaring exercises.
2. Limited mountain experience: The instructor had only one short local mountain familiarization flight at Samedan and the student was relatively low-time, yet they conducted close-in ridge flying in alpine terrain.
3. Low, slow ridge flight: Witnesses and another glider pilot reported the ASK 13 flying close to the Muottas Muragl slope at an estimated 25–30 m above ground and about 10 km/h slower than a Ka-7, in turbulent Malojawind conditions.
4. Stall near hillside: While turning away from the mountain at low height, the glider lost airspeed and entered an incipient stall with a sudden drop onto the left wing.
5. Incorrect stall reaction: The instructor apparently reacted improperly to the stall at low altitude, allowing or causing the aircraft to transition into a spin or steep spiral rather than promptly recovering.
6. Spin/spiral descent: The ASK 13 rolled and rotated around its axis into a steep nose-down spin or spiral dive, rapidly losing the little remaining height above the slope with airbrakes still retracted.
7. Crash - fatal: After roughly three-quarters of a turn in a steep nose-down attitude, the glider struck the Muottas Muragl hillside and was destroyed, killing both occupants on impact.