For a self-professed naval power, the U.K. has seen surprisingly large gaps develop in its maritime surveillance capability in recent years, a trend the Defense Ministry is setting out to reverse.

Both unmanned and manned aircraft options are being considered to address the shortfall, but even if most projects pass muster—and funding can be secured in a period of budget austerity—the ability to monitor and control sea-lanes from the air will likely not be fully restored until the end of the decade.

One key gap challenging the U.K. was created by the budget-driven decision in the 2010 Strategic Defense and Security Review (SDSR) not to field the Nimrod MRA4 maritime patrol aircraft. This leaves the U.K. without a long-range platform to track and engage submarines from the air, and the decision is often cited as one of the SDSR's most difficult capability sacrifices.

With the ink barely dry on the SDSR and many implementation steps yet to be put in place, the U.K. is weighing what would be required to reverse the decision and avert the capability gap. Air Vice Marshal Mark Green, the Defense Ministry's director for joint and air capability transformation, tells Parliament's defense committee that the decision on reconstituting the maritime patrol aircraft (MPA) capability will likely be determined as part of the 2015 SDSR.

An internal Defense Ministry study found that new aircraft would need to be purchased to fill the MPA gap. “The underlying view of the [Defense Ministry] is that an aircraft is likely, over the medium term, to be the solution that actually fills the gap that was created when we took the Nimrod out of service,” Green says. However, he adds that right now, “there is no requirement to buy an MPA.” The SDSR process will assess where maritime patrol fits in with the overall requirements.

Meanwhile, industry is preparing for a potentially new program. Lockheed Martin and Marshall Aerospace have floated concepts for a C-130-based maritime patrol system; Boeing would look to leverage its P-8, being fielded by the U.S. Navy.

To help sustain its MPA skill set, the U.K. has established the Seedcorn program, one part of which aims to maintain know-how by placing troops with other militaries. The program should provide the U.K. with a bridge to recreating the MPA capability up to 2019.

Green says there are existing platforms that could meet the U.K.'s MPA requirements in time, even if a new system is not acquired until 2015.

In the run-up to the 2015 SDSR, Defense Ministry staff will examine the requirements more closely and look into whether an off-the-shelf option could satisfy them.

But the U.K. may move to strengthen its naval airborne intelligence-collection capability in the meantime, perhaps through fielding a ship-based tactical unmanned aircraft. Meeting that requirement is a “near-term” endeavor, Green says.

The maritime requirement has long been recognized as unaddressed, but that was accepted, given the focus in recent years on military operations in Iraq and Afghanistan. Green notes that since the 2010 defense review, however, “the defense environment has changed.” With forces out of Iraq and being drawn down in Afghanistan, the maritime gap is taking precedence again.

In the coming year, military officials plan to determine the type of vehicle required through several capability demonstrations. Industry officials say it is not clear if the U.K. would buy a small or larger tactical unmanned aerial vehicle for its ships.

Qinetiq and Northrop Grumman, for instance, are talking to the Royal Navy about developing an unmanned version of the Gazelle helicopter, along the lines of the Fire-X conversion of Bell 407s in the U.S. Thales and Boeing are working on an unmanned Little Bird concept for France, which could also play in the U.K. Schiebel has been promoting its much smaller Camcopter UAV.

The Royal Navy's UAV options could be linked to the U.K. government's aircraft carrier design choice, which is under debate because of the cost of modifying existing designs for catapult-launch and arrester-gear operations. London is expected to abandon the SDSR decision to buy the F-35C and instead acquire the short-takeoff-and-vertical-landing F-35B.

But eliminating the catapult launch and arrester gear from the carrier (a move associated with the shift to the F-35B) would limit the U.K.'s options for carrier-borne unmanned aircraft, warns Lee Willett, head of maritime studies at the Royal United Services Institute.

The Defense Ministry work is being underpinned by a recent study of information, surveillance and targeting concepts that examined which systems the U.K. could afford in the next 15-20 years.

There is also pressure on the U.K. to look at other capability options. Tony Rix, a consultant and former Royal Navy admiral, argues that hybrid air vehicles, UAVs and satellite technology must be considered to meet future needs.

Green says those are longer-term options and that while many can take on the maritime surveillance part of the mission, they cannot perform the patrol element of engaging a target. Down the road, he sees unmanned underwater vehicles taking on that mission, though the technology will not be ready for another 20 years.

The Sentinel R1 airborne standoff radar (Astor) program could play a maritime surveillance role, even if it could not attack a target, but the SDSR targeted it for retirement once Afghanistan operations wind down. Military officials indicate that a move is afoot to retain the aircraft past 2015, and that it could be upgraded to take on sea-surveillance responsibilities.

The U.K. notes that the core Astor fleet has grown to five similarly capable aircraft, now that the first one delivered, ZJ690, has been brought up to the standard of the other four.