Pilot error was the most likely cause of a helicopter crash which killed its millionaire owner, an inquest heard.

Businessman Colin Sanders, 50, was killed when his twin-engine Squirrel helicopter crashed near his family home at Souldern Manor, near Bicester, on January 28. He died instantly.

Capt David Miller, a senior inspector with air accident investigators in Farnborough, told the Oxford inquest on Thursday it was impossible to determine exactly what happened in the last few seconds of the fateful flight.

He told the jury it was most likely that Mr Sanders, a self-made millionaire who was one of richest men in the country, became disorientated as he practised take-off and landing manoeuvres from the helipad at his home.

He said: "It is my hypothesis that during the second take-off and during part of the climb, he possibly encountered a huge cloud of mist.

"Had he continued to climb he would have lost sight of the ground, and he did not feel able to continue on. He started to go below the mist and in doing so, he may have encountered disorientating conditions, and he was unsure of his surroundings."

Capt Miller said Mr Sanders began descending "at a very high rate" without realising it. He added: "He recognised this too late and was unable to avert a collision with the ground. Corrective control was being applied, albeit it was not enough." Capt Miller said that disorientation can take the form of a 'tumbling sensation' but pilots are trained to ignore this and to trust their instruments.

He said at night, pilots lose visual cover and have to rely more heavily on their instruments.

The crash happened at 6.50pm and the weather was described as fine, although local mist patches were beginning to develop. Visibility was described at between 1,200 metres and 1,500 metres.

Capt Miller added that he believed Mr Sanders was "disorientated and developed a high rate of descent". Capt Miller told the jury he performed a flight retracing the final moments of Mr Sanders's life and calculated the nose was pointing 23 degrees down and took about six seconds to descend 200ft. The helicopter crashed at a rate of about 100 knots. Tests were carried out on what remained of the engines and fuselage and the parts were found to be in proper working order. Mechanical failure was an unlikely cause of the crash.

Eye-witnesses reported seeing a 'bright orange flame' and an aircraft 'lighting up the sky' as it crashed.

Pc Clive Mansell, from Bicester police station, giving documentary evidence, said he received the emergency call at 6.55pm and arrived at the crash site at 7.02pm. He said "I saw a body lying in a heap next to the twisted metal." There were no other passengers on board the aircraft.

The jury recorded a verdict of misadventure.

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