Occurrence
On 17 May 2022 at 12:58 UTC, a winch launch of an Alexander Schleicher ASK-13 sailplane at Balen/Keiheuvel Aerodrome (EBKH) resulted in an accident. The sailplane, with two persons on board, was undertaking an introductory flight. The pilot occupied the forward seat, and the passenger the rear seat. An assistant strapped in the passenger and provided pre-flight instructions.
Pre-Flight and Takeoff
The pilot performed pre-flight checks according to the sailplane's checklist. The small aft ventilation window left of the passenger's seat was closed by the assistant. The pilot closed the canopy before the tow cable was attached. After the accident, the pilot stated he could not confirm he actually pushed the canopy closing ball grip forward, as this action was routinely performed. The signal to start takeoff was given, and the winchman increased winch speed. The sailplane began climbing as expected. Initially, the pilot noted that the speed was too low (75 km/h). It is not known whether the winchman accelerated at any point.
Canopy Opening and Response
When the sailplane reached an estimated height of 80 m (pilot's estimate) or 100 m (winchman's evaluation), the ground crew observed the canopy in the open position. The winchman noticed an abnormal reflection. The pilot reacted immediately by pulling the release handle, releasing the tow cable at approximately 150 m. The pilot lowered the nose and determined that a straight-ahead landing was not possible. He decided to perform a 180-degree turn to land on the reciprocal runway. The pilot reported that the canopy opened with force, catching him by surprise. He was exposed to relative wind, lost his sunglasses, and had difficulty seeing due to wind and pressure on his eyes. He lost flight references and the slip string. He chose not to jettison the canopy to avoid damaging the rudder.
Landing and Aftermath
Upon completing the turn, the pilot felt the airspeed was too low and lowered the nose further. He does not recall whether he looked at the airspeed indicator. The sailplane struck the ground hard with a steep nose-down attitude on the middle of the runway. The left wing tip hit the ground. Witnesses did not observe a flare. The sailplane bounced, veered left, exited the runway, and came to a stop after colliding with a tree bordering the airfield. The pilot climbed out and assisted the passenger. Ground crew and bystanders provided assistance. The pilot complained of back pain without lasting effects; the passenger sustained minor injuries.
Aircraft and Pilot Information
The ASK-13 (construction number 13665, built in 1987) is a two-seat glider with a fabric-covered wing and welded steel tube fuselage. The canopy is locked by a sliding metal bar with pins that engage keepers. The locking mechanism is spring-loaded; the operator must push the ball grip fully forward to ensure full engagement. After the accident, a flight instructor verified the closing system and found it operational. All structural damage was caused by the hard landing, including substantial damage to the nose, left wing tip, and right wing. The pilot, aged 71, held a sailplane pilot license since 1991 and had 800 flight hours on various types. In the previous 12 months, he had flown 26 flights on the ASK-13, with 4 in the last 3 months.
Meteorological and Flight Path Data
Meteorological conditions at nearby station EBLG at 11:50 UTC indicated wind from 160° at 8 knots, variable between 130° and 250°, temperature 24°C, QNH 1020 hPa, CAVOK. The flight path was reconstructed using GPS data from the FLARM device installed on the aircraft. No flight recorders were installed as not required.