Accidente del L-13 Blanik en Unterer Schafberg resulta en fatalidad y lesión
El 28 de julio de 1975, un LET L-13 Blanik se estrelló en el Unterer Schafberg en Suiza. El planeador, pilotado por un piloto de planeador experimentado con su hija como pasajera, entró en pérdida y chocó contra la ladera oeste de la montaña. El piloto falleció y la pasajera resultó herida. La investigación determinó que el accidente probablemente se debió a una pérdida de sustentación cerca de la cresta, con posibles factores contribuyentes como tácticas de vuelo inapropiadas y una mala gestión de los flaps Fowler. El planeador fue destruido en el accidente.
- Ridge soaring flight: After winch launch and thermaling near Muottas Muragl, the pilot flew the Blanik along the Schafberg ridge in weak lift with his daughter in the rear seat.
- Low speed near terrain: In weak ridge lift the pilot likely flew close to minimum sink speed, with limited speed margin despite being in close proximity to the slope.
- Fowler flaps extended: The aircraft was being flown along the Schafberg with the Fowler flaps approximately half extended, altering stall behaviour at low speed near the ridge.
- Stall onset near slope: While flying close to the west slope of the Unterer Schafberg, the glider suddenly dropped its right wing, indicating a stall at or below minimum safe speed.
- Flaps retracted in stall: As the right wing dropped, the pilot retracted the Fowler flaps, a control input later shown in tests to commonly precipitate a spin from this condition.
- Spin and height loss: The Blanik entered a steep right-hand spin or steep turning descent, completing roughly one to two rotations and losing substantial height with very limited clearance from the slope.
- Crash - fatal: Unable to recover or turn away in the remaining space, the glider impacted the west slope of the Unterer Schafberg at a steep angle, killing the pilot and seriously injuring the passenger.