RAF and Navy search and rescue services are to be partly privatised despite political opposition, the Ministry of Defence (MoD) has confirmed.
The RAF carries out rescues using Sea King helicopters
The Joint Search and Rescue Helicopter (SAR-H) project will proceed as a Private Finance Initiative.
The Scottish National Party had warned that replacing the services could hit standards and lead to job losses.
But the MoD insisted the new set-up would be just as effective and deliver better value for the taxpayer.
The (SAR-H) project will go forward as a joint MoD and Maritime and Coastguard Agency (MCA) PFI project.
Decisions regarding helicopters, basing and contact duration have yet to be taken, the MoD said.
Helicopter cover is co-ordinated from RAF Kinloss in Moray and it is provided by the RAF at Lossiemouth in Moray, and by the Royal Navy at Prestwick, Ayrshire.
At present services are operated from 12 bases around the UK by helicopters run by the RAF, Royal Navy and the MCA.
RAF Boulmer in Northumberland also covers much of south and east Scotland.
Canadian-based CHC Helicopters has already been awarded the contract to run MCA operations from 2007-2012, including at Sumburgh in the Shetland Islands and Stornoway in the Western Isles.
Ministers said there would still be "a high proportion" of military air crew alongside civilian fliers under the new system, which they said would last well into the 21st Century.
Procurement Minister Lord Drayson said they would bring together the three strands of current search and rescue teams - the Navy, the RAF and the coastguard service - into one harmonised service.
He said: "We recognise that the current UK SAR Helicopter providers deliver a first-class service.
"However, the fact remains that the helicopters will need replacing over the next decade."
The SNP warned against replacing military expertise.
SNP MP for Moray Angus Robertson, whose constituency includes Lossiemouth, has put down a Commons motion demanding the plans are scrapped.
He said the privatisation of a lifeline service such as search and rescue was wrong.
"This is a cost-cutting exercise by the MoD who are cash-strapped as a result of military overstretch around the world.
"This is a vital service and I don't think it is the kind of thing that the private sector should be involved in.
"It is correct for military air crews to continue to operate the new helicopter fleet but concerns will remain about the privatisation arrangements, and the government should publish the contracts in full."