El ASK 23 entra en pérdida por cizalladura de ladera y aterriza en las copas de los árboles
Un piloto con poca experiencia en vuelo de ladera, en un ASK 23 en la Hasenmatt, bajó de la velocidad de pérdida, se hundió en los árboles hasta el suelo; el planeador quedó destruido, el piloto ileso. En ascendencia de ladera débil y turbulenta hacía «ochos»; tras un giro de 180° y un regreso inmediato hacia la ladera, la velocidad cayó a unos 50 km/h. El centrado en el límite trasero hacía el pilotaje sensible en cabeceo; una racha de 10 kt bastó para la pérdida. Sin recuperar velocidad, optó por un aterrizaje en los árboles. Factores: reserva de velocidad insuficiente, muy poca experiencia en vuelo de ladera, centrado trasero.
- Ridge training flight: During the second afternoon training flight after aerotow to 2,000 m, the pilot flew ridge soaring along the Hasenmatt between about 1,200 and 1,300 m, in short figure-eight patterns.
- Low ridge experience: The pilot had very limited overall gliding experience and only a brief prior ridge-flying checkout, so he was not familiar with windshear hazards in ridge soaring.
- Aft CG and turbulence: The glider was loaded with the centre of gravity aft in the allowable range, reducing stability, over ridge terrain known for turbulent airflow with only weak lift.
- Turn away from slope: While flying figure-eights along the ridge, the pilot made a 180° left turn away from the slope and then immediately turned right, during which airspeed dropped rapidly below minimum.
- Stall and height loss: The glider entered a mush/stall with airspeed reported down to about 50 km/h, losing height quickly despite the pilot applying full control inputs to turn right and away from the slope.
- Emergency landing attempt: Recognizing that he could not regain sufficient airspeed or control, the pilot committed to an emergency landing and extended the airbrakes.
- Crash - no injury: The glider touched down in treetops on the slope, slid down the trees to the ground, was destroyed, and the pilot exited uninjured.