Tony Osborne London

The U.K. is facing a four-year gap in its carrier-borne airborne early warning (AEW) capability as the Defense Ministry searches for a successor for the long-serving Westland Sea King Mk7 fleet.

Initial work is underway to replace the fleet of radar-equipped Sea Kings, which have been providing aerial surveillance for Royal Navy carriers and battle groups since the early 1980s. The program, called Crowsnest, is charged with finding the replacement for this capability and a range of options is being studied.

According to questions asked in Parliament on Nov. 19, Crowsnest will enter its assessment phase in 2013 and has “not yet passed its main investment decision point,” says Philip Dunne, minister for defense equipment, support and technology. The project became part of the Defense Ministry's core equipment program under the Planning Round 12, announced in May.

Throughout the post-war years, the Royal Navy had an organic AEW capability for its conventional aircraft carriers, but when these were retired in the late 1970s, replaced by the Invincible-class anti-submarine warfare ships—essentially light carriers designed to carry ASW helicopters and BAE Systems Sea Harrier fighters for air defense—commanders believed there was no longer a need for AEW capability.

But the 1982 Falklands conflict, which saw several U.K. ships sunk or damaged due to Argentine air and missile attacks, led to the creation of a helicopter-borne AEW capability, which has rapidly evolved. Today, the Royal Navy has 13 Sea King Mk7 helicopters equipped with the Thales Searchwater radar system. In recent years, the rotorcraft has also undertaken the overland surveillance mission in Afghanistan, supporting U.S. Marine Corps operations in rural areas of Helmand Province, using the radar's ground moving target indicator mode.

The Searchwater radar is mounted on the Sea King in a distinctive radome protected by a Kevlar bag, which inflates and then lowers underneath the aircraft inflight. But these Sea Kings, along with those used for search-and-rescue and amphibious assault mission, will be eliminated from the U.K. inventory at the end of 2016, while the first two Mk7s will be retired in 2013. Crowsnest envisages the replacement capability to be in service in 2020, in time for use on the new Queen Elizabeth-class carriers. But this leaves a four-year gap in which U.K. ships will not have AEW, although Dunne added that other systems could fill the void in the interim.

Officials working on Crowsnest have determined that any replacement system will be fitted to the AgustaWestland EH101 Merlin HM2 helicopter. The Navy Merlin fleet is currently being upgraded from HM1 to HM2 standard as part of the Merlin capability sustainment program being undertaken by AgustaWestland and Lockheed Martin. The first Merlin Mk2s are due to reenter Royal Navy service in 2013.