During an aerobatics training flight, the aircraft, a Pitts S-2A Pitts Special (G-ODDS) struck the ground whilst in a spin. The aircraft was destroyed and both pilots were fatally injured.
A definitive cause could not be determined, but it is likely that the commander became incapacitated during a spin and the student was unable to recover the aircraft in time. The aircraft had a Centre of Gravity position that was out of limits aft, which would have reduced the capability of the aircraft to recover and extended the time to do so. Unapproved devices, which adjusted the rudder pedal positions, were found on the rudder cables but were unlikely to have been a contributory factor.
Safety action has been taken by the operator regarding aircraft weight and balance to ensure accurate weights are used.