Accidente del ASK 13 en el aeródromo de Grenchen tras liberación inesperada del remolque
El 9 de abril de 1980, un alumno piloto volando un Alexander Schleicher ASK 13 despegó para un vuelo de entrenamiento en solitario desde el aeródromo de Grenchen. Poco después del despegue, a aproximadamente 80 metros de altitud, el cable de remolque se liberó inesperadamente del avión remolcador. El planeador entró en un giro a la izquierda que se acentuó de manera incontrolable, llevando a un accidente a las 15:59 hora local. El alumno piloto sufrió heridas mortales, y el ASK 13 fue destruido. El incidente se atribuyó a la pérdida de control tras la liberación inesperada del remolque.
- Aerotow initial climb: The student pilot departed solo in ASK-13 HB-926 on aerotow from Grenchen and climbed normally to about 80 m above ground.
- Unexpected tow release: Shortly after passing the western end of the airfield at approximately 80 m AGL, the tow cable unexpectedly released from the tow aircraft while the glider was flying slightly low behind it.
- Low altitude, student pilot: The cable release occurred at very low altitude with a relatively inexperienced student pilot who had previously shown anxiety in unexpected situations.
- Left turn after release: After recognizing the situation and transmitting 'cable break' on the radio, the student initiated a left turn instead of maintaining straight-ahead flight and building speed over suitable landing terrain ahead.
- Steepening descending turn: The left turn became progressively steeper with the glider increasingly nose-down, airspeed apparently low, and the aircraft entering an uncontrolled, high pitch-down attitude with about 300° change in heading.
- Crash - fatal: The glider, still attached to the tow rope at its nose hook, impacted the ground in a steep nose-down attitude with slight left bank, fatally injuring the student pilot and destroying the aircraft.