A navigator fell from an RAF Tornado while flying above Norfolk at about 450mph because his ejection seat was not properly fitted, an inquest heard.

Father-of-two Michael Harland, 44, who worked as a civilian navigator for BAE Systems, which services Tornados based at RAF Marham, died after taking off from the airbase on November 14, 2007.

The second day of the inquest at Sprowston Manor Hotel, near Norwich, today heard that his seat slipped from the aircraft as the jet was flying upside down 6,000ft above South Creake in north Norfolk.

He was testing the two-seater fighter jet after new parachutes were fitted.

Mr Harland suffered multiple injuries and his body was later found in a field at North Barsham, near Wells.

Accident investigator Stephen Moss told jurors that the 'misengagement' of a locking device which prevented the seat from sliding when the jet flew upside down was the most probable cause of the accident.

Mr Moss said it was 'very, very unlikely' that component parts of the locking mechanism had failed.

Deputy Coroner for Norfolk Jacqueline Lake was told an RAF Board of Inquiry concluded the cause of the accident to be 'the incorrect engagement of the seat locking mechanism on installation of the seat to the aircraft'.

Board of Inquiry members made more than 40 recommendations, the inquest heard.

Mr Moss said the tail fin had hit the seat as Mr Harland emerged from the Tornado, causing damage which would have prevented either of two parachutes fitted in the seat headbox from working.

The inquest heard yesterday that modifications had been made to the ejection seat just prior to the accident, as part of ongoing changes to all Tornados.

DS Chris Burgess told the inquest that a police investigation was launched in January 2008 but no criminal actions resulted from the incident.

Mr Harland, a former RAF squadron leader, was married with two children and lived in Woodlands Drive, Colsterworth, a village near Grantham in Lincolnshire.

He had been working at RAF Marham for about four years after leaving the RAF and had served in the Gulf War. The plane involved in the incident made it safely back to Marham. The inquest is expected to last five days.