A 79-year-old pilot who fatally crashed into a runway after suddenly going into a dive from 100ft (30m) may have had a heart problem, a report said.
The pilot of the Rotorsport MT-03 aircraft died in the crash at Turweston Aerodrome in Buckinghamshire on 28 July 2016.
The Air Accidents Investigation Branch (AAIB) said there was no evidence of mechanical problems with the aircraft.
Its report said the pilot had a serious "undiagnosed cardiac condition".
He died "as a result of multiple injuries sustained in the accident", the report said.
The severity of the pilot's cardiac condition meant it may "caused unconsciousness", causing the crash.
The AAIB report said he was an experienced private aeroplane pilot who was nearing the end of a course to get a gyroplane pilot's licence.
He had completed 41 hours of gyroplane flight instruction and was undertaking solo flights and practising landings.
A gyroplane, sometimes called an autogyro, uses an unpowered rotor to develop lift and an engine-powered propeller to drive it forward.