What happened
On 4 August 2012, a Glaser-Dirks DG-100 glider, registration G-DDFN, was performing a private cross-country flight near Kirriemuir, Angus. Following a successful winch launch, the pilot began a series of thermalling turns. During the flight, the aircraft entered a steep, nose-down spin. The pilot managed to recover from this initial spin after approximately two turns.
After the recovery, the aircraft flew north before turning towards the airfield. During this phase, the aircraft's descent rate increased significantly. The glider subsequently entered a second spin from an altitude of approximately 750 ft. Unlike the first instance, the aircraft failed to recover from this second rotation and impacted a crop field. The pilot sustained fatal injuries in the crash, and the aircraft was destroyed.
The investigation
Investigators examined the wreckage and recovered an electronic flight logger, which provided GPS-derived data including track, groundspeed, and altitude. The data revealed that the aircraft's airspeed had decayed to near stalling speeds during the period leading up to the second spin.
Technical examination of the airframe showed that the airbrakes were in an extended position at the time of impact. While the airbrake control handle showed signs of being manipulated, investigators could not determine if the brakes were opened intentionally to lose height or if they had failed to lock properly after a previous use. The investigation also considered the pilot's medical state, noting evidence of hypertensive heart disease, though no evidence suggested an incapacitating event occurred.
Findings
- The aircraft entered the second spin because of low airspeed while turning to the right.
- The extension of the airbrakes likely increased the stalling speed and the altitude required for a successful recovery.
- The pilot's airspeed had decayed to levels very close to the aircraft's stall speed during the maneuvers.
- There was no evidence of any pre-impact mechanical failure or defect in the aircraft's structure or flight controls.