Puchacz training: third spin not recovered from ~460 m AGL

The instructor and student of a Puchacz were fatally injured in an unrecovered training spin near Husbands Bosworth; aircraft destroyed. After aerotow release at ~915 m AGL the crew performed two left-hand spins with normal recoveries. A third spin entered at ~460 m AGL continued for about five turns; the glider was last seen in a steep left turn below 30 m before the left wing struck. No pre-impact failure was found and no cause could be established. The student had only practised spinning in a more benign K13; the instructor's recent currency on Puchacz was very limited.

1. Aerotow training flight to ~915 m AGL: An SZD-50-3 Puchacz two-seat trainer was aerotow-launched from Husbands Bosworth on a training flight (instructor + student), released normally at ~915 m AGL. The probable focus was spinning practice.
2. Two spins to left with normal recoveries: Witnesses in a nearby Rotax Falke saw the Puchacz enter a spin to the left from a nose-high attitude, complete a normal recovery after about 1-1.5 turns, regain height, then enter a second left-hand spin from a normal gliding attitude with a normal recovery; the glider appeared to be climbing away under control.
3. Limited Puchacz currency on both seats: The student's prior spinning training had been carried out only in a K13, which has more benign spin characteristics than the Puchacz; he had not yet spun a Puchacz. The instructor held a BGA Assistant Instructor Rating; his recent currency on the Puchacz was very limited — about 9 hours total on type and ~1.5 hours in the previous 28 days.
4. Third spin entered at ~460 m AGL: Witnesses on the ground saw the glider's nose pitch up steeply and the aircraft enter a third spin to the left at an estimated 460 m AGL — substantially lower than the previous two recovered spins.
5. About five turns; no recovery observed: Ground witnesses watched the Puchacz complete an estimated five turns in a steep nose-down left spin, with no apparent change in attitude and no recovery action observed; one witness thought the rotation rate may have increased slightly before the glider disappeared from view behind a ridge. No radio transmissions were received.
6. Left wing strike below 30 m; both fatal: A second pilot saw the glider in a left turn at less than 30 m AGL; it cleared a hedge before the left wing struck the ground followed by the nose, at about 60° pitch-down. Both occupants were fatally injured (the instructor died after rescue from the wreckage); the airframe was destroyed. The investigation found no pre-impact disconnect in the primary controls and could not establish a conclusive cause; possibilities including pilot incapacitation and a control restriction/jam were considered but not confirmed. The left airbrake was found extended after impact; engineering analysis judged the bevel-gear support disbond to be impact-induced rather than pre-existing.