A fatal light aircraft crash could have been caused by the captain suffering a severe heart problem, accident investigators said.
Captain Robert Bull, 40, of Hornchurch, Essex, lost control of the plane, which crashed in a field in Chigwell, Essex on October 3 last year.
Both he and First Officer Francis Simmonds, 46, from Luton, Bedfordshire, were killed.
The men had been in charge of one of two planes which could have been used to take West Ham United chairmen David Sullivan and David Gold to the club's game against Sunderland at the Stadium of Light.
The post-mortem examination of Mr Bull found evidence of an acute dissection of a coronary artery, indicating that he may have suffered from impaired consciousness or even sudden death.
The pathologist was unable to determine whether his condition occurred before or after the crash, but the report stated: "If there is no other cause identified for the crash then it is both possible and plausible that this was the precipitating factor."
A report by the Air Accidents Investigation Branch (AAIB) found that although it could not be stated "unequivocally" that the pilot became incapacitated, "on the balance of probabilities" it is "likely" that he lost control of the aircraft to due medical reasons.
Mr Simmonds was unable to take over and recover the aircraft in time to avoid it crashing into trees at the edge of a field.
The Beech B200 Super King Air was sometimes used by West Ham United chairmen David Sullivan and David Gold.
Following the crash, they said they had been lucky not to have been on board.
The pair had been due to fly from Stapleford Airport to the North East where their team had a Premier League match with Sunderland.
They were due to fly on one of the two light aircraft available to them - including the plane which crashed.
Mr Sullivan said at the time: "The aviation company, London Executive Aviation (LEA), have two planes and we have flown on that particular
plane about 50 times.
"It was 50/50 whether we got on the plane that crashed or the other one. It's a real shock. My heart goes out to the families of the pilots, it's
very, very sad."
There was a last-minute change of plan when they arrived at the airport but found it was closed.
LEA confirmed Mr Sullivan and Mr Gold were due to fly with the company, but on a different aircraft to the one involved in the accident.