With three teams already lined up at the starting gate, the US Navy has attracted a competitive field for the newly launched EPX programme that the US defence industry normally reserved for the most high-profile requirements. Yet, the opportunity to replace 11 ageing Lockheed EP-3E ARIES II aircraft - the electronic intelligence-gathering subset of the USN's maritime patrol aircraft fleet - has sparked a wide-open and diverse race despite its relatively small numbers.

Although the size of the EPX contract dwarfs the ongoing battle for the US Air Force KC-X contract, the USN requirement could rekindle the fight between military derivatives of Boeing and Airbus airliners that has characterised the KC-X contest. Boeing is actively pursuing a 737-based platform and Northrop Grumman is publicly considering the Airbus A321.

Alternatively, Lockheed Martin's Skunk Works division is studying replacement ideas ranging from off-the-shelf turboprops and turbofans to undisclosed "advanced concepts".

All three companies - Boeing, Lockheed and Northrop - have received small study contracts to kick off an at least six-year-long process to deliver a successor to the EP-3E, but with far greater capability.

"These contractors will help us determine the technical criteria necessary to build a strong foundation for the EPX programme," Capt Joe Rixey, EPX programme manager, said in a statement.

The USN currently employs the EP-3E as a signals intelligence platform. In conventional operations, the aircraft gathers hostile radar signatures and intercepts enemy communications to help inform the surface fleet's picture of the opposing side's order of battle.

On top of this mission the USN is planning to overlay a requirement for an entirely new mission - intelligence, surveillance, reconnaissance and targeting (ISR&T).

That means adding imaging sensors, active radar arrays and on-board processors to identify targets in real-time, then hand-off the co-ordinates to strike aircraft or ship-based missile launchers.

It is a mission area in which the USN has already begun experimenting. Last year, industry officials confirmed to Flight International that at least seven specially modified Lockheed P-3Cs have been deployed with a canoe-shaped radar called the Littoral Surveillance Radar System (LSRS), a Boeing/Raytheon technology that performs the ISR&T function.

On 13 September 2006, Boeing demonstrated one potential use for the LSRS. A Standoff Land Attack Missile-Expanded Response (SLAM-ER) destroyed a simulated SA-10 missile launcher in the desert. The missile was sent real-time targeting data by an LSRS-equipped P-3C after being launched from a Boeing F/A-18.

Boeing confirms the LSRS capability is under evaluation as part of its concept study for the EPX programme, says Paul Summers, Boeing director of airborne signals intelligence [SIGINT] campaigns.

"The LSRS or an LSRS-like capability will be in that trade study mix," Summers says. "A lot of variables have to be taken into play here. Will [LSRS] work in an environment where we also have to perform SIGINT? Will it fit on our airplane?. We have to consider all the variables, and not solely the performance."

The USN's options for a contractor are also likely to be highly scrutinised. Despite the broad competitive interest for EPX, the USN faces potential scepticism over whether the bidding process will be completely fair.

For the anti-submarine warfare mission, the USN already plans to buy 108 Boeing P-8As - a 737-800 airframe modified with a -900 wing and a weapons bay - to replace more than 225 P-3Cs.

As the EP-3E fleet is a SIGINT adjunct to the P-3C, the USN may face economic pressure to replace both fleets with the same platform. The USN has previously stated plans to buy between 14-19 aircraft to replace the 11 EP-3Es.

As expected, Boeing is pushing the USN to adopt this strategy. "Wouldn't it be a good approach if they had roughly 20 additional EPX variants that were derived from the same basic platform?" Summers asks. "We think the fact that the navy will have a P-8 platform in inventory will be a significant weighing factor in terms of platform solution."

Lockheed told Flight International that it has experience as the original EP-3E manufacturer and also in "designing, planning and forecasting needed growth" for the EPX platform. Lockheed also "has not ruled out turboprops from the rade space and will examine how far they can be brought to meet the requirements of the EPX programme".

Meanwhile, Northrop has teamed with L-3 Communications, the current missions systems integrator for the EP-3E fleet. Alan Easterling, Northrop's EPX capture lead, says it is considering a range of aircraft from business jets to large narrowbodies in the 86,000kg (190,000lb)-class, including the P-8A and the A321.

"We like to believe we're as agnostic as possible," Easterling says. "Anything less than that biases the outcome."

The USAF's KC-X tanker is another key battle between Airbus- and Boeing-based platforms: http://www.flightglobal.com/kcx

Source: Flight International