Prince William's Hampshire flying tutor was killed in a high-speed motorcycle crash as he tried to overtake a truck which failed to indicate it was turning right, an inquest heard today.
James Hassell, 36, was pronounced dead at the scene of the accident on the A417 near Faringdon, Oxfordshire, on March 10 last year.
The inquest, at Oxford Coroner's Court, heard the ''very distinguished helicopter pilot and instructor'' was also a keen motorcyclist who enjoyed going for long motorbike rides around the countryside at weekends with his friend and colleague Matthew Coverley.
Mr Coverley told the hearing he and Mr Hassell, known as Jim, had just left the village of Faringdon and were travelling down the narrow country lane when he noticed a green truck travelling about 300 metres in front of them at around 9.35am on the Saturday.
He said Mr Hassell was around 6-10m in front of him, with his own motorbike staggered to the left of his bike.
As they approached the vehicle he said they both accelerated to between 70-80mph in order to overtake it but the truck then began to turn right into a farm entrance without indicating, slowing down or appearing to notice them.
Mr Coverley said: ''I didn't see any indication on the truck, neither prior to or as it turned.
''Jim steered towards the left of the carriageway to attempt to avoid the truck.
''The truck was travelling in a continual motion, as if it has not seen Jim.
''In my mind it was all in slow motion.
''I saw Jim's body hit the truck. I continued to break hard, stopping at the side of the road.''
Mr Coverley said he was sure that the driver of the truck had not used his indicator.
''Both Jim and I are experienced riders and we always look for indications and we would not even attempt to overtake if we thought the truck was turning,'' he said.
But giving his own evidence, the truck's driver, Polish national Marek Kucala, told the inquest that he had seen one of the motorcycles and had indicated that he was turning.
He said: ''I indicated much earlier, before the entrance to Manor Farm as I knew where I was about to turn.
''The first time I checked my mirrors I didn't see anyone.
''When I moved to the centre of the road I checked the mirrors for the second time and I noticed the motorcycle.''
Speaking through an interpreter, he said that as he saw the motorcycle was trying to overtake him he then tried to swerve back to the left side of the road to let him pass.
''It's really difficult to describe as all of it happened in a fraction of a second,'' he added.
Mr Hassell, who was based at RNAS Yeovilton in Somerset and lived in Middle Wallop, Hampshire, gave the Duke of Cambridge helicopter flight training five years ago.
The inquest heard married Mr Hassell's body was thrown over the hedge by the force of the crash and he landed in a field.
A paramedics car and air ambulance attended the scene and medics performed CPR as he was still breathing at first but was then pronounced dead.
A post-mortem examination found the cause of death to be a mesenteric tear with intra abdominal haemorrhage.
Toxicology tests found no traces of alcohol or drugs in his system and there was nothing in his medical history that was likely to have contributed to the crash.
A breathalyser test on Mr Kucala at the scene was found to be negative. He was described by police as ''clearly very shaken''.
Giving evidence, Terry Anderson, a collision investigator with Thames Valley Police, said he arrived at the scene of the crash later that morning.
He told the inquest that when he tested the truck's indicators he found them to have a much dimmer output than they should have had and were dirty which also made them harder to see.
''Certainly not what you would expect of a well maintained vehicle,'' he added.
He also found the Isuzu rigid goods vehicle's battery was flat and needed to be jump-started although the breaklights and indicators still worked.
Further tests two days later found further levels of deterioration and the indicators would not work at all.
Police staff vehicle examiner Philip Balderstone, who tested the vehicle on the Monday, told the inquest he found the truck's electric system to be ''severely affected by defective batteries'' and it also had a cracked windscreen and broken driver's seat.
But he added that as this was two days after the crash, Mr Anderson's findings were the most relevant to the state of the vehicle at the time of the accident.
Mr Anderson said the truck was 2.1m wide while the lane was 2.8m wide, leaving a narrow space of just 0.7m.
A mark where Mr Hassell's right shoulder had hit the truck in a ''glancing blow'' could be seen on its nearside, he added.
But he said that Mr Coverley's description of Mr Hassell's motorbike being 5m away from the truck when it turned was impossible as at the speed he was travelling he would have been moving at a distance of 31m per second.
The actions that he had described Mr Hassell carrying out - of breaking and moving to the left - would have taken at least two seconds, he said.
He told the inquest that as there were no independent witnesses, ''whether the indicators worked, or their brightness, will never be known.''
Mr Kucala, who was employed to collect animal carcasses from farms, was interviewed by police later that day and again on May 2 but no action was taken against him.
Coroner Darren Salter recorded a verdict of accidental death.
He said: ''As often is the case there is some conflicting evidence to areas in particular concerning the indicators.
''Mr Kucala says he indicated. Mr Coverley says he didn't see any indication. He doesn't believe there was any.
''All I can say about that is there is conflict in that.
''We don't know how bright the indicators would have been at the time of the collision, if indeed there was indication from Mr Kucala.
''One thing that is clear is that this accident happened very suddenly and very quickly.
''It has become apparent that perhaps we're talking not about a fraction of a second, but a few seconds.
''Clearly speed was a significant factor.''
Earlier, as he opened the inquest, the coroner offered his condolences to Mr Hassell's family.
He said: ''I'm sure he was very much loved and I also note he was a very distinguished helicopter pilot and instructor.
''I do offer my condolences in the loss of Jim in these circumstances.''