What happened
On 4 December 2016, a Schleicher ASW 24, registration G-CFNG, was participating in a private gliding session at Brentor Airfield, Devon. The day was characterized by significant turbulence and mountain wave activity, with winds reaching up to 30 knots. Following a period of unsettled weather, the pilot decided to resume launches.
During the winch launch, the aircraft accelerated rapidly, but at an altitude of approximately 120 feet, the weak link between the cable and the glider parted. The aircraft climbed briefly to a peak height of about 280 feet before the pilot initiated a left turn to attempt an abbreviated circuit back to the airfield. During this maneuver, the glider encountered intense downdrafts and a significant loss of airspeed. The aircraft entered a rapid, descending left turn and struck the ground in a heavily banked, nose-down attitude in a gorse-covered area north of the runway. The pilot sustained fatal injuries.
The investigation
The AAIB examined the wreckage, the recovered weak link, and flight data from the aircraft's onboard cameras and gliding computer. The investigation confirmed that the weak link had functioned as designed, parting due to a load exceeding its yield strength, likely caused by the turbulent atmospheric conditions.
Investigators also analyzed the performance of the Schleicher ASW 24 and compared it to the conditions experienced by another glider that had flown earlier that day. The investigation noted that while the pilot had sufficient altitude and runway length to land straight ahead, the decision to turn into the wind exposed the aircraft to severe sinking air that made completing the circuit impossible.
Findings
- The primary cause of the accident was the encounter with significant sinking air during the attempted circuit, which depleted the aircraft's energy.
- The weak link separation was triggered by high loads resulting from the turbulent weather.
- The pilot did not fully adopt the recommended BGA recovery attitude, which involves a specific pitch to maintain visibility of the landing area ahead.
- The decision to attempt a circuit rather than landing straight ahead was likely influenced by the desire to avoid a lengthy retrieval and the presence of sufficient runway length for a forward landing.