Tutor and Standard Cirrus collide during aerobatics in see-and-avoid airspace

The Tutor pilot and a cadet were fatally injured when a Grob G115E Tutor on an air-experience aerobatic sortie collided with a Standard Cirrus glider in uncontrolled airspace; the glider pilot parachuted safely, both aircraft destroyed. Visibility exceeded 25 km. The Tutor pulled up into a vertical manoeuvre; its left wing struck the glider's fin and the tail broke away. It probably entered a spin, recovered, then dived steeply to ground. A medical condition limited the Tutor pilot's look-out and probably incapacitated him on impact; both aircraft were on see-and-avoid in a high-traffic gap between controlled airspaces.

1. Aerobatic air-experience sortie: A Grob G115E Tutor was conducting a cadet air-experience flight from RAF Benson, routinely including aerobatic manoeuvres. A Standard Cirrus was flying a 300 km cross-country task. Both aircraft were operating in the gap between RAF Brize Norton CTR and RAF Benson ATZ in fine weather with visibility over 25 km.
2. Tutor pilot look-out restricted: The Tutor pilot had a long-term medical condition that restricted the mobility of his head and affected his ability to conduct an effective look-out to the RAF standard. Concerns about his look-out had been raised by instructors during his instructional-technique course but were not identified during AEF flight and cockpit checks.
3. High-traffic gap, see-and-avoid only: Traffic levels in the airspace gap were very high on the day. Neither aircraft was receiving an air traffic service. The Tutor had no onboard traffic alerting system; the glider was fitted with FLARM, which was not designed to detect the Tutor's transponder. Both aircraft were relying on see-and-avoid in an area of high traffic density.
4. Convergence unsighted by either pilot: The Tutor was on a constant closing bearing with the glider in the moments before the collision. The glider was probably hidden behind the Tutor's windscreen frame; the glider pilot sighted the Tutor below him and attempted evasive action but could not avoid the collision.
5. Pull-up; left wing hits glider fin: After at least two aerobatic manoeuvres, the Tutor pitched up into a vertical manoeuvre. The outer section of its left wing struck the fin and right tailplane of the Standard Cirrus.
6. Glider tail breaks away: The glider's tail section separated and the glider became uncontrollable. The glider pilot opened his canopy and parachuted to safety.
7. Tutor spins, recovers, dives steeply: Despite collision damage assessed as not preventing controlled flight, the Tutor probably entered a spin, recovered, and then descended in a steep dive from which it did not recover. The cadet released his harness and moved the canopy operating handle to the open position, but the canopy jettison sequence was not completed and the time available was insufficient to abandon the aircraft.
8. Both in Tutor fatal; glider pilot bails: Both occupants of the Tutor were fatally injured at ground impact, which was not survivable. The Standard Cirrus pilot parachuted to safety and was uninjured. Both aircraft were destroyed. Causal: neither pilot saw the other in sufficient time to avoid the collision. Contributory: a medical condition limited the Tutor pilot's look-out and the high traffic density in uncontrolled airspace increased collision risk; the apparent absence of recovery action by the Tutor pilot points to incapacitation in the collision itself.