What happened
On September 16, 2017, a winch-launched flight at the Heppenheim glider airfield resulted in a serious accident. The pilot was performing an introductory flight to become familiar with the Rolladen-Schneider LS 7-WL aircraft. During the launch, the aircraft was initially accelerated to approximately 150 km/h, exceeding the maximum allowable winch launch speed. In response to the pilot's radio request to slow down, the winch operator reduced power, causing the airspeed to drop significantly.
During this period of decelerating speed, the tow rope became disconnected. The pilot, unaware that the rope had released, maintained a high angle of climb. At an altitude of approximately 50 to 60 meters AGL, the pilot attempted to execute a shortened circuit to land on runway 15L. While initiating a left turn, the aircraft lost sufficient airspeed and entered an accelerated stall, pitching sharply to the left. The glider struck a line of trees and bushes, resulting in serious injuries to the pilot and heavy damage to the aircraft.
The investigation
The BFU examined the flight data from the aircraft's FLARM Redbox, which reconstructed the flight path and confirmed the altitude loss during the maneuver. The investigation also reviewed the pilot's training records, the winch operator's actions, and the airfield's operational procedures. Investigators analyzed the aircraft's maintenance history and the technical condition of the winch and tow rope, finding no mechanical failures. The investigation also looked into the training curriculum of the flight club regarding procedures for interrupted winch launches.
Findings
- The primary cause of the accident was the failure to maintain sufficient airspeed during a turn following a launch interruption, which led to an accelerated stall.
- The pilot was flying a new aircraft type and lacked experience with low-altitude maneuvers in such critical flight phases.
- The pilot's decision-making was limited by training that only covered two specific procedures (straight-in landing and shortened circuit) and did not include more complex maneuvers like a reverse circuit.
- The pilot's reaction to the speed drop—requesting more speed via radio rather than immediately disconnecting the rope—contributed to the critical flight state.
- The winch operator's significant reduction in power contributed to the rapid loss of airspeed.