What happened
On August 22, 1966, a Rhönlerche II glider, registration HB-586, was performing a training flight at the Schänis airfield. During a winch launch, the designated breaking point of the tow rope failed. At the time of the incident, visibility was significantly reduced due to heavy rain. Following the rope failure, the student pilot initiated a left-hand turn. However, due to insufficient airspeed, the aircraft entered a stall, resulting in the left wingtip and the fuselage striking the ground.
The investigation
The investigation focused on the mechanical failure of the towing equipment and the aerodynamic behavior of the aircraft under degraded weather conditions. Investigators examined the sequence of events following the separation of the tow rope and the impact of the low visibility and low speed on the pilot's ability to maintain controlled flight.
Findings
- The primary cause of the accident was the failure of the tow rope at its breaking point during the winch takeoff.
- Reduced visibility caused by rainfall hindered the pilot's situational awareness.
- The aircraft lost sufficient airspeed during the maneuver, leading to a wing stall and subsequent impact with the terrain.
- The accident resulted in two light injuries to the occupants.