Summary
On 12 August 2022 at 1054 UTC, a Schleicher AS-K 13 glider, registration G-DCMK, experienced a premature release from its aerotow during an instructional flight from Talgarth airfield in Powys, Wales. The glider, with a student and instructor on board, landed in a field. Both crew members sustained serious spinal injuries and have since recovered. The glider was destroyed.
History of the Flight
The student, acting as handling pilot, and the instructor were conducting a training flight aimed at bringing the student to solo standard. Pre-flight preparations, including rigging checks and weight and balance, were completed satisfactorily. The takeoff was planned in a north-westerly direction under crosswind conditions. The student was expected to make all radio calls. During the takeoff run, the instructor kept his hand on the release knob until confident of the student's aileron control, then removed it. The student kept his hand on the release knob throughout the roll, per BGA guidance. The ground run was slightly longer than normal due to crosswind, high temperature, and takeoff weight. After becoming airborne, the student called out that the tow rope had detached. The instructor observed the rope trailing the towing aircraft. The student did not recall pulling the release knob. The instructor took control, turned toward lower ground, and spotted a field with a favourable slope and long grass. While turning, both pilots saw electricity cables, and the glider struck the ground. The student exited immediately; the instructor remained in the cockpit.
Aircraft Information
G-DCMK was a two-seat glider typically used for training, manufactured in 1975 (serial no. 13305). It was purchased by the gliding club in June 2017 and maintained by members. The original design included two tow releases: a nose release for aerotowing and a belly hook for winch launching. At some point, the belly hook was removed and replaced with a light spring to maintain cable tension, which did not affect the nose release. At the time of the accident, the nose tow release was a Tost E72 (serial no. 18058). A previous uncommanded release had prompted replacement of the E85 release on 17 June 2022; the E72 was fitted then.
Meteorological Conditions
At the time of the accident, skies were clear with a light north-easterly wind of less than 10 kt and a temperature of 25°C.
Aerodrome Information
Talgarth airfield lies on the western edge of the Black Mountains at an elevation of 970 ft amsl. It has multiple grass runways providing three takeoff and five landing options. The north-westerly takeoff run is the longest, sloping downhill. The area is surrounded by hilly terrain with limited forced-landing options.
Examination and Analysis
Examination of the glider and tow rope showed no anomalies with the rope or rings. One cockpit cable guide, integral with the left instrument panel mounting, had detached from the fuselage, but it was unclear if this was pre-existing or accident-related. The tow release had been removed, preventing functional testing. Manufacturer examination revealed that the over-centre adjustment screw had been removed; the white sticker was not the factory security seal. The adjustment screw was removed during installation because it fouled against the structure, whereas the previous E85 had a recessed screw. Removal of the screw would increase the load required to open the release, not cause inadvertent release. The manufacturer noted a special recessed version of the E72 is available. Club investigators tested another K13 and found no inadvertent release from pilot foot movement. No technical issue with the complete release system could be established. It is possible pilot or student inadvertently moved the release knob.
Conclusion
The investigation could not conclusively determine why the tow rope disconnected. An inadvertent input on the release knob or an unidentified mechanical failure could not be ruled out.