Fatal crash Tiger Moth plane engine 'misfired'
A Tiger Moth plane which crashed killing two people was "sounding awful and misfiring" before it came "corkscrewing" down, a report found.
The pilot, 64, and the 67-year-old passenger were killed in the crash in a crop field near Shaftesbury, Dorset.
The "air experience" flight was the first of the day from Compton Abbas Airfield in August 2017.
An Air Accidents Investigation Branch (AAIB) report said it had been unable to identify any defects with the plane.
A flying instructor at the airfield, who tracked the aircraft after the pilot reported problems with the engine, said the nose of the aircraft pitched down sharply and the aircraft rolled into a steep descending turn.
Shortly afterwards a column of smoke was seen from a nearby crop field.
The report said damage caused by the post-crash damage made it impossible to eliminate a problem with the 82-year-old plane's magnetos, ignition system and carburettor.
"A problem with any of these could have caused the reported symptoms," it added.
The AAIB said it had found no evidence the flying controls had failed before the accident.
The report found the pilot, who had 22,240 hours of flying time, had radioed the airfield to say he was returning after reporting problems with the engine.
Clive Hughes, from DH Heritage Flights Limited which runs flying experiences from the airfield, said: "Our heartfelt thoughts continue to be with the families of the bereaved.
"The AAIB's report reaches no definitive conclusion about the cause of the accident because of insufficient data.
"It is frustrating for everyone that we do not understand how this accident happened."