What happened
On 16 August 2025, a LAK-1tB FES Mini glider, registration G-CLTX, was performing a winch launch at the South Wales Gliding Club in Monmouthshire. During the ascent, the aircraft's airbrakes deployed without pilot input. The pilot, focused on post-launch checks, did not immediately realize the brakes had opened, but soon observed an excessive sink rate and a significant drop in airspeed. Although ground personnel attempted to warn the pilot via radio, the message went unheard.
In an attempt to recover airspeed, the pilot lowered the nose, but the aircraft's altitude had already depleted to a critical level. Unable to clear a nearby line of trees while maintaining safe flight parameters, the glider collided with the treetops. The impact brought the aircraft to a halt approximately 15 feet above the ground. The pilot sustained serious injuries, and the aircraft suffered damage to its wings, fuselage, and tail.
The investigation
The AAIB investigation established that earlier in the day, a technical issue occurred while attaching the winch cable. During the process, the cable ring struck the hook with enough force to derail the hook control cable from its guide pulley. To rectify this, the pilot accessed the pulley and cable from within the cockpit to rerail it.
It was determined that this corrective action inadvertently left the airbrake handle in an unlocked state. During the subsequent winch launch, the pitch angle of the aircraft caused the unrestrained handle to slide rearwards, triggering the deployment of the airbrakes.