What aircraft was involved and where did it happen?

The accident on 2022-05-17 involved a Alexander Schleicher ASK-13, at EBKH, BE.

What was the probable cause of the accident?

The canopy was not adequately secured before takeoff, leading to an in-flight opening that disrupted flight control and caused a high-impact landing.

Canopy Failure Leads to Hard Landing for Belgian Sailplane

An Alexander Schleicher ASK-13 experienced an in-flight canopy opening during a winch launch, resulting in a substantial impact and aircraft damage.

What happened

On May 17, 2022, an Alexander Schleicher ASK-13 was performing a local, non-commercial winch launch at the Balen/Keiheuvel Aerodrome (EBKH) in Belgium. The flight was intended as an introductory session for a passenger. During the ascent, at an altitude between 80 and 100 meters, the aircraft's canopy unexpectedly flew open.

The sudden opening of the canopy exposed the pilot to intense airflow, which disrupted flight references and caused significant physical distraction. The pilot immediately activated the release handle, disconnecting the tow cable at approximately 150 meters. To manage the situation, the pilot executed a 1-80-degree turn to approach the reciprocal runway. Due to the low altitude and the loss of control stability, the pilot performed a steep, nose-down approach to maintain airspeed. The aircraft subsequently struck the runway with high force, causing the left wing tip to hit the ground. The sailplane bounced, veered left, and eventually exited the airfield after colliding with trees. Both occupants sustained 2 minor injuries.

The investigation

The AAIU(Be) conducted a limited-scope investigation focusing on the conditions surrounding the canopy failure and the subsequent landing. Investigators examined the aircraft's locking mechanism, which uses a ball grip to secure pins into keepers. While the mechanism was found to be operational, the pilot could not confirm if the canopy had been fully secured during pre-flight checks. The investigation also reviewed historical data regarding similar canopy-opening incidents in other sailplane types and analyzed the pilot's checklist procedures.

Findings

The primary cause of the incident was the canopy not being properly secured prior to takeoff or being inadvertently opened during flight.
The sudden exposure to wind during the canopy opening significantly hindered the pilot's ability to maintain stable flight and control the aircraft's trajectory.
The pilot's inability to confirm the locked status of the canopy during the pre-flight routine contributed to the occurrence.
The hard landing and subsequent excursion from the runway were direct results of the loss of control following the canopy failure.