Incident Overview
On August 26, 2007, a fatal accident occurred at the special aerodrome of Iserlohn-Sümmern in Germany. A Robin DR 400/180R Remorquer, operated by a local gliding club, crashed into a coniferous forest shortly after takeoff. The pilot, a 79-year-old private pilot with approximately 4,100 hours of total flight experience, died at the scene. The aircraft was destroyed upon impact, and no third-party damage was reported.
Operational Context
At the time of the incident, mixed operations were underway in violation of local aerodrome regulations, which prohibit simultaneous motorized flight and winch-towing glider operations. At 10:45 local time, the pilot departed for a training flight. Shortly after, at 10:46, a winch launch was initiated for an ASK 13 glider. The Remorquer landed at 10:49 with its engine shut down. While the pilot was on the ground, another glider (Ka 8) began a winch launch at 10:52. Simultaneously, the Remorquer attempted to take off again after restarting its engine.
Accident Sequence
During the initial climb of the Remorquer, it approached the falling winch cable from a glider that had just released. A crosswind from the right-front drove the cable diagonally across the runway. Ground observers and air traffic control issued warnings to turn left to avoid the hazard, but these were not heeded. The left wing of the aircraft struck the Dyneema fiber cable, which severed the torsion box down to the main spar. This contact caused severe deceleration and a sharp left roll, resulting in the aircraft crashing into the forest approximately 25 meters southwest of the runway end.
Investigation Findings
The German Federal Aviation Office (BFU) determined that no technical defects were present on the airframe or engine prior to the crash. The primary cause was identified as the simultaneous conduct of winch operations and motorized flight, which is explicitly forbidden by the aerodrome's operating procedures. Additionally, communication between the pilot and ground control was deemed insufficient, as warnings regarding the cable's position were not effectively acted upon. The lateral distance between the winch launch site and the landing strip was also noted to be inadequate for safe mixed operations.