History of the Flight
The pilot conducted two flights on the day of the accident. The first, a winch-launched flight in the morning, proceeded without issue. After lunch, the pilot launched again via winch, releasing from the tow at 900 ft above ground level. The glider turned right, flying along the Dunstable Downs ridge, then made a gentle turn through approximately 180° followed by an orbit. Shortly thereafter, witnesses observed the glider pull up steeply, level off at about 300 ft, bank left, and then enter a spiral dive to the right. After turning approximately 270°, the glider impacted the ground in a steep nose-down attitude. The pilot sustained fatal injuries.
Weather Conditions
Weather at the gliding site near Dunstable was good with a blustery south-easterly wind estimated at 10 to 15 kt, with stronger gusts. Recorded wind data from a nearby site indicated 130° at 14 kt, gusting 24 kt. Visibility exceeded 10 km, and scattered cumulus clouds had a base of 4,500 ft. A red wind sock was flown, indicating that only instructor pilots and those with a Silver gliding qualification were recommended to fly. The pilot did not hold a Silver qualification nor was an instructor, though he had recently flown in challenging conditions in the Pyrenees.
Aircraft and Pilot Information
The glider was a Schleicher ASW 24, registered G-CGDU, manufactured in 1991 (serial no. 24118). Its maximum allowable takeoff mass was 500 kg; empty mass was 253 kg. With the pilot’s weight plus parachute and equipment at 110 kg, the all-up mass for the accident flight was 363 kg. The pilot, aged 65, held a BGA Gliding Certificate and had 274 total flying hours, with 10 hours on type.
Examination and Recorded Data
Two GPS receivers and a PDA were recovered from the wreckage. The iPAQ recorded GPS position and altitude once per second for both flights. Data from the accident flight showed that after the pull-up, the glider’s groundspeed decreased to 47 kt at the top of the manoeuvre before banking left. Given the tailwind component of at least 10 kt, the glider’s airspeed was close to the 1g stall speed of approximately 37 kt for its weight. Witnesses reported the glider skidding or yawing with its nose to the right prior to impact.
Engineering examination revealed that the glider was structurally complete before impact, with landing gear retracted and airbrakes closed. No pre-impact failures were found. The damage pattern was consistent with striking the ground in a right-hand spiral dive.
Medical and Pathological Information
The post-mortem examination determined that the pilot died from multiple injuries sustained in the accident. There was no evidence of drugs or alcohol consumption, nor any natural disease that could have contributed to the event.
Operating Manual Details
The ASW 24 operating manual includes stall speeds and spiral dive recovery procedures. At the accident weight, the 1g stall speed with airbrakes closed was about 37 kt. The manual describes recovery from a spiral dive by applying opposite rudder and aileron opposite to the direction of turn.