What happened
On June 6, 1970, at approximately 14:30, a training flight was underway at the Fricktal-Schupfart airfield. A Rhönlerche II glider, registration HB-595, was being towed by a Piper Super Cub for a student pilot's instructional session. Shortly after takeoff, at an altitude of approximately 50 meters, the towline unexpectedly disconnected from the glider's release mechanism.
Following the release, the glider entered a right-hand turn in an attempt to return to the airfield. During this maneuver, the aircraft experienced a sudden loss of altitude. The glider made uncontrolled contact with the ground, sliding between a hangar and several parked motor aircraft before ultimately colliding with a winch (an out-of-service automobile). The occupants of the glider, a flight instructor and a student, were uninjured, though the glider sustained heavy damage and the winch was slightly damaged.
The investigation
The investigation examined the mechanical state of the glider's release mechanism and the flight maneuvers performed by the crew. Investigators reviewed the flight logs and experience levels of both the instructor and the student. The student had not flown for nearly a year prior to the accident, while the instructor was an experienced pilot with significant recent flight hours.
Technical inspections of the release hook and the release mechanism on HB-559 were conducted both before and after the accident. The investigation also considered the meteorological conditions, noting significant wind and turbulence present at the time of the event.
Findings
- The investigation could not determine the exact reason why the towline released from the glider's hook, as both the hook and the release mechanism were found to be in perfect working order.
- The flight crew's decision to execute a right-hand turn at such a low altitude was identified as the primary contributing factor to the accident.
- The maneuver was deemed inappropriate given the low altitude and the prevailing wind conditions; a safer alternative would have been to maintain a straight course and perform a landing on the adjacent downward-sloping meadow.
- There was a lack of immediate intervention by the instructor. The instructor waited for a reaction from the student before taking control, which was considered inappropriate given the student's lack of recent flying experience and the critical nature of the situation.
Safety action
No specific safety recommendations were recorded in the final report, though the investigation highlighted the necessity for instructors to intervene immediately during critical flight phases when training students with lapsed proficiency.