Ka 4 Rhönlerche II stall and crash during training flight at Buttwil airfield

On April 20, 1981, a Ka 4 Rhönlerche II was involved in a fatal accident at Buttwil airfield in Switzerland. During a training flight, the student pilot was released from aerotow after the tow plane experienced engine issues. While attempting to return to the airfield, the glider stalled at a low altitude and crashed, resulting in the destruction of the aircraft and the death of the pilot. The investigation identified insufficient airspeed at low altitude as the primary cause, with contributing factors including the unexpected tow release and limited experience of both the student and tow pilots.