At least 10 pilots and crew have quit their posts at RAF Kinloss in the past decade because of safety concerns over the ageing Nimrod fleet, it has been claimed.
David Morgan, an aviation expert, said he was aware of a number of Nimrod personnel who had left the Scottish air base following worries about the aircraft's systems, including air-to-air refuelling.
He was speaking after a coroner said that the entire RAF fleet of Nimrod aircraft has never been airworthy and should be grounded.
Andrew Walker's verdict came at the end of an inquest into the deaths of 14 servicemen based at RAF Kinloss who lost their lives when their plane exploded in mid-air just minutes after undergoing air-to-air refuelling in Afghanistan in September 2006.
Last night the Ministry of Defence would not comment on Mr Morgan's specific claims, but stressed that the RAF placed the "highest priority" on airworthiness and the safety of its personnel.
Mr Morgan, who has flown with Nimrod crews over the past 20 years, said: "I know of at least 10 air crew who left because they were getting worried about the maintenance level of the Nimrod and its reliability.
"But to say the aircraft was not airworthy, I feel, was misleading. The Nimrod aircraft is very strong and ... the problems were with the aircraft systems, including the fuel systems."
Mr Morgan, who is based in the town of Forres, a few miles from Kinloss, added that air-to-air refuelling had "never been successful" as the Nimrod had not been designed for such an operation.
He added that the fears of pilots and crew had been over the fleet's hydraulic, electronic and fuel systems.
Meanwhile, Bob Hellyer, a retired squadron leader and former Nimrod pilot who was based at RAF Kinloss, said: "Air-to-air refuelling missions were, for me, not a good idea." He added that the system, which was introduced during the Falklands War, should have been stopped when the conflict came to an end.
In a statement, Air Marshal Sir Barry Thornton, the RAF's most senior engineer, said: "We have stopped air-to-air refuelling and no longer use the very hot air systems in flight.
"This eradicates any dangers from the serious design failures noted by the coroner." He added that "enhanced maintenance" made the aircraft "safe to fly".