What happened
On June 5, 2013, during the Open Military Gliding Championships at Malden airfield, a DG-808C glider, registration PH-1488, crashed during a winch launch. The flight was part of a competitive event organized by the Royal Netherlands Air Force.
As the winch cable was tensioned and the aircraft began its ascent, the glider rotated around its transverse axis almost immediately. Witnesses noted that the aircraft's pitch angle was steeper than usual, with the tailwheel making contact with the ground. As the aircraft climbed, it suddenly dropped over the right wing, entered a spin, and struck the ground with the nose and left wing. The pilot, a 4-experienced 46-year-old man, was killed in the accident, and the aircraft was destroyed.
The investigation
The Dutch Safety Board (OVV) examined the aircraft, the winch operation, and the pilot's recent flight history. Technical inspections of the DG-808C revealed no mechanical failures. While the elevator was found in an upward position, investigators determined this was caused by the forces of the impact rather than a pre-existing malfunction. The flaps were found to be in the correct +8 degree setting for a launch.
Regarding the winch operation, the investigation found that the winch operator used plastic cables, which can cause faster acceleration, but the operator's experience and the lack of evidence of excessive acceleration ruled this out as a cause. The investigation also noted that a brown breaking link with a strength of 8500 N was used, which slightly exceeded the recommended maximum of 8250 N for this specific aircraft type, though this was not considered a contributing factor.
Findings
- The primary cause of the accident was that the pilot allowed the aircraft to rotate too much during the initial phase of the winch launch.
- This excessive rotation caused the aircraft to reach a critical angle of attack, leading to a stall and the subsequent loss of control.
- The pilot had performed unusually steep starts during the first two days of the competition, and although the competition safety officials had issued warnings and briefings to prevent such maneuvers, these interventions did not prevent the fatal accident.
- The pilot's recent experience with winch launches in this specific aircraft was limited, having performed only one such launch in the PH-1488 since July 2012.