What happened
On 27 July 2019, a Standard Cirrus 75 glider, registration G-DDGX, was undergoing an aerotow launch at Gwernesny Airfield. During the initial stages of the ground roll, the aircraft's horizontal tailplane detached from the fuselage and fell to the ground. Although ground personnel attempted to signal an immediate stop, the message failed to reach the tug pilot or the glider pilot. The aircraft continued its takeoff roll and became airborne, climbing rapidly before the tow cable disconnected. Without pitch control, the glider's nose dropped, leading to a steep descent and a nose-first impact with the ground. The pilot sustained fatal injuries and passed away five days later.
The investigation
Investigators examined the wreckage and the rigging process used prior to the flight. The investigation established that the tailplane had been incorrectly attached during the assembly process. Specifically, the locking lever was found in a forward position rather than the required aft position, even though the safety pin was installed. This configuration allowed the mechanism to appear secure during standard control checks while remaining unstable under aerodynamic loads.
Testing revealed that the propwash from the tug aircraft provided enough force to lift the improperly secured tailplane. The investigation also looked into the communication chain, noting that the forward signaller's position and the reliance on hand signals made the emergency stop signal difficult for the tug pilot to perceive amidst the engine noise and visual distractions of takeoff.
Findings
- The tailplane was mis-rigged, resulting in a connection that was not structurally secure for flight.
- The locking lever was positioned forward of the safety pin, a state that could pass a positive control check without revealing the defect.
- Visual stop signals from ground personnel were not detected by the tug pilot due to the signaller being outside the primary field of view and the high noise levels.
- The flight manual for G-DDGX contained outdated or irrelevant instructions regarding the tailplane attachment mechanism.
Safety action
Following the accident, the British Gliding Association (BGA) received a recommendation to define minimum requirements for adequate communication systems during glider launches. Additionally, a recommendation was made to the European Union Aviation Safety Agency (EASA) to require a visible means of detecting incorrect alignment of tailplane locking levers on similar aircraft types.