The pilot of the plane which crash-landed killing Chelsea Football Club vice-president Philip Carter probably became disorientated in thick fog, an accident report said today.

It is also possible that a benign lesion in the pilot’s brain could have contributed to the accident which killed all four on board the twin-engined Squirrel helicopter, the report from the Air Accidents Investigation Branch (AAIB) said.

Mr Carter, 44, and his son Andrew, 17, were returning from Merseyside after seeing their team lose on penalties to Liverpool in a Champions League semi-final on the night of May 1, 2007.

The pilot Stephen Holdich, 49, from Chidham, West Sussex, was taking the Carters and businessman Jonathan Waller, 42, from Liverpool to a private landing site near Peterborough, the AAIB said.

The report added that, as it approached its destination, the helicopter - owned by Mr Carter - probably encountered an area of shallow fog and low cloud. The pilot descended and, possibly using an illuminated haulage yard and quarry for guidance, attempted to fly below the cloud to complete the flight.

Either imminent contact with the ground or impending contact with trees ahead forced the pilot to climb, “where it is possible that he became disorientated and lost control”, the report said.

The helicopter crashed in Bedford Purlieus Wood, near Mr Carter’s house in the village of Thornhaugh, near Peterborough, around midnight.

The report said: “Although the effects of a lesion discovered in the temporal lobe of the pilot during his port-mortem examination was not considered a causal or contributory factor in the accident, the aviation pathologist who reviewed the autopsy reports considered that such lesions, whilst not necessarily causing total incapacitation, could, potentially impair one’s ability to control a helicopter safely.

“Therefore the possibility that the lesion could have contributed to the cause of the accident could not be fully dismissed.”

The AAIB added: “In the absence of any technical defect or failure being found during the examination of the wreckage, it was concluded that after the pilot elected to continue the flight, at night, beneath a low layer of thin cloud, he was forced to make a climbing turn to the left, possibly to avoid the ground and/or an area of woodland, and that, during this manoeuvre, he became disoriented and descended into trees.”

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