RAF Group Captain David Haward died yesterday afternoon, after failing to eject when his single-seater Harrier jump-jet crashed into a field north of Stainton, County Durham, during a routine training flight.

Married with two children, Mr Haward, 45, was awarded the OBE in 1995, and was the most senior pilot on the base.

A Durham Constabulary spokesman said a board of inquiry into the accident would be set up to investigate the cause of the crash.

The Harrier jump jet was flying out of RAF Wittering, near Stamford, Lincolnshire.

A Ministry of Defence spokesman said the RAF GR7 Harrier from 20 Squadron, an operational unit, was on routine training exercises.

Mr Michael Littlefair, 32, a beef and sheep, farmer said he saw the Harrier crash and explode.

''I was about two miles away and I saw two planes flying parallel when one of them just flipped 90 degrees and crashed into the ground. There was a huge explosion and a fireball.''

At the scene of the accident, RAF spokesman Squadron Leader Chris Taylor said: ''At 13.50 today, one of three RAF Harrier jets returning from a routine sortie was involved in an incident which resulted in one crashing.

''The aircraft was not involved in any training exercise linked to the Gulf.''

Squadron Leader Taylor explained that due to the large amount of fuel around the wreckage and possible dangerous fumes from the man-made fuselage it could be some time until the site was clear and environmentally safe.

Early indications had suggested that the accident may have been caused when the jet clipped power cables.

Mr Brian Robson, a local farmer, rejected that suggestion, saying: 'First I heard an unusual noise coming from the aircraft.

''I ran outside and saw the plane straight in front of me. Its nose dived into the ground and burst into flames.

''I rang for the services and then went across the field to see if I could help anybody.

''Two other people were at the scene but there was no sign of life in the aircraft.

''By the time I arrived the flames had gone out and there was very little debris above the ground. The plane seemed to have ploughed into the soil.''