Occurrence
On 28 January 2024 at 14:15 UTC, an Alexander Schleicher ASK-13 sailplane (registration OO-ZKS) operated by the Koninklijke Kempische Aeroclub was conducting a winch-launch takeoff from runway 07 at Weelde airfield (EBWE). The pilot occupied the front seat, and a passenger holding a sailplane pilot license with an instructor rating occupied the rear seat. After external inspection and pre-flight checks, the sailplane was hooked to the winch. The pilot signaled readiness, and the winch operator commenced the launch.
During the initial phase, the sailplane lifted off and entered a light controlled ascent. At approximately 30–35 meters above the grass runway, the pilot perceived abnormal conditions: the winch cable had not broken, but acceleration was noticeably lower than normal. The winch operator attempted to increase power by moving the throttle handle but found it stuck; RPM could not be increased beyond 1200, whereas 1700 RPM was required. The operator immediately radioed "break, break" to the pilot. The pilot pushed the control stick forward to round off before ground contact. The cable detached, though the pilot stated he did not operate the disconnect handle. The sailplane struck the ground nose-first, bounced, and came to rest about 150 meters from the starting point.
Injuries and Damage
The pilot sustained minor injuries and exited the aircraft unaided. The passenger, seated above the main wheel, suffered severe spinal injuries and was transported to a hospital for surgery. The sailplane sustained substantial structural damage to the empennage and belly.
Context
The winch was a Leopard 4 (serial 34-6003-Z, built 2008) with push-pull cables for engine controls. Post-accident inspection revealed that the throttle control cable from the operator to the engine was crushed, causing the push-pull cable to become stuck in its synthetic sheath. The cable had a previously adjusted position that induced a lateral force on the inner casing, leading to wear. The winch maintenance program did not require inspection or scheduled replacement of the push-pull cable, and regular maintenance failed to detect the deterioration.
Weather conditions at the time were wind 5 knots from 140°, temperature 8°C, QNH 1022 hPa, with good visibility and cloud ceiling. The airfield is a former military field with a concrete runway and a grass area for glider operations; no air traffic control services were provided.
The Koninklijke Kempische Aeroclub operates at Weelde airfield. This was the 13th winch start of the day.