Incident Overview
On August 23, 2023, an accident occurred involving an Alexander Schleicher ASK 21 sailplane at the Segelfluggelände Rheinstetten in Germany. The investigation file number is BFU23-0776-3X. The aircraft was operated by a local gliding club and was registered for civil traffic in Germany. During a winch launch, the tow line detached from the sailplane while it was at a low altitude, resulting in a hard landing on the grass runway.
Flight Details and Sequence of Events
The pilot, a 59-year-old holder of a LAPL(S) license with approximately 1,624 hours of glider experience, was accompanied by a passenger who was a member of the gliding club but did not hold a valid license. The first winch launch that day was successful, reaching an altitude of about 300 meters above ground level (AGL). The second launch began at 15:34:40 local time. According to the pilot, the tow line tension suddenly decreased, and the line detached from the aircraft. The sailplane then descended steeply without the pilot being able to arrest the descent effectively. The passenger described a similar sequence, noting that the aircraft stopped gaining altitude before pitching nose-down.
Aircraft and Equipment
The ASK 21 is a two-seat, high-performance glider with a composite construction, manufactured in 1983 (serial number 21145). At the time of the accident, it had accumulated 6,421.51 flight hours. The aircraft was equipped with a FLARM collision avoidance system. The winch used was an Ulbrich-Industrieelektronik ESW-2B electric model, manufactured in 2022. It utilized 5 mm Dyneema tow lines and a G73 centering coupling. The last inspection of the winch was conducted on July 22, 2023.
Investigation Findings
The investigation concluded with a factual presentation without analysis or conclusions. Physical evidence at the scene showed the nose wheel made initial contact approximately 213 meters from the launch area, leaving a 6-meter mark in the ground. The aircraft then rolled for another 115 meters before coming to rest. Examination of the sailplane revealed cracks in the main gear fairing but no structural damage to the airframe or control surfaces. At the winch station, the left tow line was retracted, while the right line remained fully extended. The tow line, winch parachute, and weak link were found connected on the ground near the winch.
Injuries and Damage
Both occupants sustained serious injuries. The pilot suffered severe spinal injuries, while the passenger sustained chest injuries. The sailplane was lightly damaged, with no third-party damage reported.