The deployment of the new Nimrod MRA4 to RAF Kinloss will not happen until the end of this year, it has emerged.
The delay was confirmed by the Ministry of Defence in a parliamentary answer to local MP and SNP defence spokesman Angus Robertson.
The aircraft is due to replace the 30-year-old MR2, grounded in March.
Dozens of jobs have already been lost at RAF Kinloss due to the withdrawal of the MR2, which was taken out of service a year early.
The MoD had previously said that the new MRA4 aircraft would arrive at the Moray airbase during the summer.
Fears have also been expressed that the base could be affected in the government's upcoming Strategic Defence and Security Review.
The base is a major local employer and generates millions of pounds for the Moray economy.
The news comes a day after the UK government announced a £7bn project to privatise search and rescue (SAR) services at HMS Gannet in Prestwick was on hold.
Mr Robertson told BBC Scotland's Good Morning Scotland programme that the Nimrods provided enhanced support to search and rescue crews conducting operations far out at sea.
He said the delay in deploying the MRA4s could undermine future rescues.
He added: "Now, with the introduction of the replacement Nimrods being put back, it means that this gap widens and it is literally a life and death issue because we know Nimrods, within recent months, were absolutely vital in ensuring that lives were saved.
"It actually makes the case for the retention of Kinloss because it shows and highlights how important the Nimrod aircraft are around the nation's shores and it underlines why this incoming Liberal Conservative government needs to ensure that they do not undermine the defence footprint in Scotland, which has already suffered, under the last Labour government, serious cutbacks and a massive defence underspend."