Crews are said to have had mounting concern over Nimrod systems
At least 10 Nimrod crew have quit their posts at RAF Kinloss in the past decade because of safety concerns, it has been claimed.
Aviation writer David Morgan said he knew of a number of personnel who left because of aircraft system worries.
On Friday, at the end of an inquest into the deaths of 14 men in a Nimrod explosion in 2006, a coroner called for the entire fleet to be grounded.
The MoD said it would not comment on Mr Morgan's claims.
Safety fears about the fleet were raised after a Nimrod MR2 crashed while on duty in Afghanistan in September 2006, killing the men, 12 of whom were based at RAF Kinloss.
In his summing up at the inquest into the deaths, coroner Andrew Walker said in his view the entire Nimrod fleet had "never been airworthy from the first time it was released to service" nearly 40 years ago.
Mr Morgan, who has flown with Nimrod crews over the past 20 years, told BBC Scotland: "Over the last 10 years there's been a rising level of concern about the aircraft's reliability.
"Generally this all started about 10 years ago after the first accidents."
He said the crew's concerns centred around the Nimrod's electronic, hydraulic and fuel systems.
"It's making them more and more nervous and more and more concerned as this aircraft approaches 40 years in frontline service," he said.
But Mr Morgan said that extra family pressures were forcing pilots and crew to leave the RAF.
He added: "You have perhaps two factions here, people who think that they should stay at their post and continue to operate the aircraft, and the others, perhaps with a certain amount of understandable family pressure, saying 'well this aircraft is not safe to fly any more'.
"What they do is they move to the civil airline business where there's always been demand for the last five or six years."
He said the MoD had to do something now to ensure the safety of the crews and the people who live in the areas where they operate.
It it estimated that the replacement for the current Nimrod fleet, the MRA4, is not due into service for at least five or six years.
The MoD said it would not comment, but 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 that have been present in this aircraft since the 1980s.
"These measures have been supplemented with enhanced aircraft maintenance and inspection procedures to ensure the aircraft, as it is today, is safe to fly."
He added: "We would not ask our personnel to fly in aircraft we did not believe were safe."