What happened
On March 21, 1964, a Rhönlerche II glider, registration HB-702, was performing a dual training flight at a military airfield. The flight was conducted using an aero-winch launch method, with a student pilot in the front seat and an instructor in the rear.
During the initial climb, the winch cable began to rotate continuously due to an asymmetry in the cable shuttle. At an altitude of approximately 50 to 60 meters, the cable's weak link failed. Despite the cable break, the instructor allowed the student to maintain control of the aircraft.
Rather than continuing straight ahead to land on the remaining paved runway, the student proposed a left-hand turn to return to the takeoff position. The instructor agreed to this maneuver, despite the availability of roughly 800 meters of paved runway and an additional 1,000 meters of flat grass ahead. During the turn, the instructor took control to increase the bank angle but failed to maintain sufficient airspeed. Consequently, the aircraft lost speed and stalled at an altitude of about 15 to 20 meters, striking the paved surface with the left wingtip and the nose of the fuselage.
The investigation
The investigation examined the mechanical failure of the winch system and the flight maneuvers following the cable break. Investigators noted that the instructor had not flown since November 1963, having only resumed training with a brief solo flight on the day of the accident. The investigation also assessed the available landing area, which provided ample distance for a straight-ahead landing.
Findings
- The primary cause of the accident was the decision to execute a turning maneuver to return to the launch site at an insufficient altitude.
- The winch cable failure was caused by the continuous twisting of the cable, likely due to an asymmetric cable shuttle.
- The instructor's decision to permit a turn, rather than proceeding with a straight landing, led to a loss of airspeed during the bank.
- The instructor may have been motivated to avoid the long ground transport required to return the glider to the winch site.
Safety action
No specific safety recommendations were recorded in the final report.