DOUBTS have been cast on the conspiracy theories surrounding the helicopter crash at Bournemouth Airport which killed the pilot and a businessman with Russian connections.

The poisoning of a former Russian agent Sergei Skripal and his daughter Yulia in Salisbury has led to calls for a fresh inquiry into the crash at Bournemouth Airport on March 3, 2004.

But the Daily Echo understands a number of people who encountered pilot Max Radford, 34, had concerns about his ability to fly the Augusta 109E involved in the tragedy.

And one source said most pilots would have crashed if they found themselves flying in the same conditions.

An inquest into the deaths of Mr Radford and the wealthy businessman Stephen Curtis, 45, concluded they died in an accident, while the Air Accident Investigations Branch (AAIB) blamed pilot error.

Rumours of Russian involvement have surrounded the case ever since. Mr Curtis was chief executive of Menatep, a company owned by Russian oil giant Yukos, whose owner was said to be in a power struggle with Vladimir Putin.

Mr Curtis, who owned a castle at Portland, is said to have told a friend a week before his death: “If anything happens to me in the next few weeks, it won't be an accident.”

A friend of Mr Radford’s, fixed-wing pilot John Hackney, recently told the Daily Echo: "All of us who knew Max and were friends with him said exactly the same – ‘This is not an accident’.”

MP Sir Chris Chope, whose Christchurch constituency includes the airport, has said he was always sceptical about the official explanation.

The website BuzzFeed listed the tragedy among 14 cases with Russian-connections that it said were suspicious. Yvette Cooper, chair of the House of Commons home affairs select committee, has called for those cases to be looked at again.

But other sources have expressed confidence in the AAIB’s conclusion that Mr Radford became disorientated in bad weather. Conditions were deteriorating and the pilot had flown into cloud.

“In the circumstances he was in, most non-instrument rated pilots, even experienced pilots, would crash,” a source said.

Pilot disorientation was a common phenomenon when helicopters encountered bad weather. “It kills several people in the UK every year. It happens all around the world,” the source said.

At an inquest in 2005, AAIB senior inspector Paul Hannant insisted there was no evidence that the helicopter had been sabotaged.

"I do understand the workings of a helicopter and if the helicopter had been interfered with, there would be a very limited number of areas where such evidence would be available," he said.

He added: "The pilot would have been operating in a seriously degraded visual environment during the late stages of his approach.”

Aviation psychologist John Chappelow told the inquest how pilots could become disorientated when they could not see the horizon.

"If you remove visual skills from the pilot then you will lose control of the aeroplane in, depending on the manoeuvre he's doing, 30 seconds or a minute," he said.

The inquest also heard from two flight instructors who said they had been concerned about the level of Mr Radford's knowledge of the twin-engined Agusta 109E.

Alan Davis, of Alan Mann Helicopters, said Mr Radford had come in for training on the differences between the original 109 and its 109E successor.

He said: "He was a likeable young man but I felt his confidence exceeded his competence.

"The purpose of the course he came in for was for me to explain the difference in the aircraft but it became apparent early on that his knowledge of the basic aircraft wasn't sufficient for me to be able to do that."

Mr Radford was not “instrument-rated”, meaning he was not deemed capable of flying without visibility.

Fellow instructor Richard Poppy said he believed any pilot of a 109 should be instrument-rated, although it was not a legal requirement. He was concerned about pilots without ideal experience being hired to fly complex aircraft belonging to private owners.

But he acknowledged Mr Radford – who had once flown for Sir Elton John – had been deemed competent to fly the Agusta after his training.

East Dorset coroner Sheriff Payne told jurors at Bournemouth Town Hall: "Mechanically, the helicopter was still working at the time it hit the ground. There is no evidence any explosive device was used."

The inquest jury agreed with the AAIB conclusions that the crash had happened as Mr Radford tried to land in bad weather, with lack of ground lighting and pilot disorientation as possible contributing factors.

But Mr Payne’s remarks at the time acknowledged that some people would continue to believe differently.

He said: "Almost immediately after it came to light, conspiracy theories arose, particularly because of Mr Curtis's activities, his Russian links and so on, and there are all the ingredients there of an espionage thriller.”