Summary
On 6 June 1970 at 1430 hours, a Rhönlerche II glider (registration HB-595) operated by the Segelfluggruppe Basel commenced a training flight from the Fricktal-Schupfart airfield. The aircraft was towed by a Piper Super Cub PA-18. The instructor and student occupied the rear and front seats, respectively. At approximately 50 meters above ground, the tow rope released from the glider's coupling. The crew executed a right turn to return to the airfield, but the glider made uncontrolled ground contact between a hangar and parked aircraft, subsequently colliding with a winch. Both occupants were uninjured; the glider sustained severe damage, and the winch sustained minor damage.
Aircraft and Crew
The glider was a Rhönlerche II, designed by Schleicher/Kaiser and manufactured by A. Schleicher in 1957. It was owned by the Segelfluggruppe Basel and held a valid airworthiness certificate. The instructor, born 1935, held a glider pilot license since 1958 and a flight instructor endorsement since January 1970, with 137 flight hours. The student, born 1950, held a student glider pilot license since April 1960 and had 16 hours of gliding experience; his last flight before the accident was on 19 October 1969.
Flight and Accident
Before departure, a ground crew member attached the tow rope to the glider's nose hook and performed a tension check. The glider then took off and climbed normally. Due to strong bise wind, the glider encountered a gust at about 30 meters, causing a right bank. The instructor verbally corrected the student, and the glider continued climbing. At approximately 50 meters, about 100 meters before the runway end, the tow rope suddenly released from the glider. Neither crew member reported intentionally activating the release. The student stated he heard a snap and saw the rope fly away, then instinctively initiated a right turn to return. The instructor reported waiting for the student's reaction, then taking control and deciding on a downwind landing. During the turn, the glider lost altitude rapidly and drifted toward the restaurant and hangar. The instructor attempted to land between the hangar and parked aircraft, but the glider touched down, skidded, and collided with the winch.
Damage
The two crew members were uninjured. The glider was heavily damaged in the collision with the winch. The winch, an out-of-service automobile, sustained light damage.
Investigation Findings
Post-accident examination of the glider's release mechanism found it in normal working order; no damage was identified. The source of the unintentional release could not be determined definitively. The report noted that the decision to perform a turn at low altitude with a headwind was inappropriate and hazardous. It was suggested that a straight-ahead landing or a slight turn with a sideslip and full airbrakes on an available field would have been safer. The instructor's delay in intervening and the student's decision to turn were both criticized as contributing to the accident.