ASK 13 crash at Grenchen airfield following unexpected tow release
On April 9, 1980, a student pilot flying an Alexander Schleicher ASK 13 took off for a solo training flight from Grenchen airfield. Shortly after takeoff, at approximately 80 meters altitude, the tow cable unexpectedly released from the towing aircraft. The glider entered a left turn that steepened uncontrollably, leading to a crash at 15:59 local time. The student pilot sustained fatal injuries, and the ASK 13 was destroyed. The incident was attributed to the loss of control following the unexpected tow release.
- 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.