Private companies are to be invited to compete to operate the search and rescue (SAR) helicopter services in the UK, the government has announced.
There are "no plans" to close search and rescue bases
The Private Finance Initiative scheme could see civilian aircrew operating alongside military ones at SAR bases.
The contract, starting in 2012, could last up to 30 years and be worth £1bn.
There are currently no plans to close any of the 12 SAR bases, the Ministry of Defence and the Maritime and Coastguard Agency (MCA) have said.
The MoD and MCA will continue to manage the services jointly.
The part-privatisation was announced by Minister for Defence Procurement Lord Drayson and Shipping Minister Stephen Ladyman.
The MCA currently runs four SAR bases, while the RAF operates six and the Royal Navy runs two.
Canadian-based CHC Helicopters is one of the companies likely to compete for the contract in 2012.
The company already is taking over a contract to operate the MCA bases at Sumburgh in the Shetland Islands, Stornaway on the Western Isles, Lee-on-Solent in Hampshire and Portland, in Dorset, from 2007-2012.
Part of the reasoning behind the part-privatisation is the need to replace the Sea King helicopters at the military SAR bases over the next 10 years.
Britain's search and rescue helicopter bases
Lord Drayson said the current SAR helicopters delivered a first-class service but needed to be replaced.
The MoD said decisions regarding helicopters will be "subject to dialogue" with members of the industry.
"This project provides the opportunity to bring together three strands of the current SAR providers into one harmonised service," he said.
"This high quality service will be as effective as the present one, while delivering better value for money for the taxpayer."
Mr Ladyman outlined his desire to "work towards even greater collaboration and cooperation for the benefit of all who get into difficulties at sea or around the UK coast".
MCA chief executive John Astbury said its new 2007-2012 contract would provide helicopters that were 50% faster and that new helicopters for the entire operation would "help save more lives".
Colonel John Brittain, deputy director of the equipment capability area at the MoD, has stressed that there are no plans to close bases.
He added that it would be necessary to retain a "core military capability" at the bases.
Prior to the announcement, some MPs had expressed concerns that some bases might shut and that some SAR crews could be replaced.