By Andrea Shalal-Esa

WASHINGTON (Reuters) - The U.S. military could save hundreds of millions of dollars as result of a unique decision by the Air Force and Navy to jointly base, control, train and maintain high-altitude unmanned aircraft built by Northrop Grumman Corp, senior officials said on Thursday.

Air Force Chief of Staff General Norton Schwartz and Chief of Naval Operations Admiral Gary Roughead last month signed a memorandum of agreement to maximize commonality and eliminate redundancies between the Air Force's Global Hawk program and the Navy's Broad Area Maritime Surveillance program.

The Air Force is already using its Global Hawk, or RQ-4, planes over Iraq and Afghanistan. The Navy is due to begin using its maritime version of the planes in 2015.

The Navy program is due to cost $15 billion, according to Pentagon data, while the Air Force program's costs have soared by 40 percent to nearly $14 billion due to an increase in the number of planes ordered and higher sensor costs.

Under the deal, the two services will work together on the high-flying reconnaissance drones while maintaining the separate sensors developed to meet their specific surveillance needs over land and sea.

The agreement was in the works for over six months, but was finalized just as Defense Secretary Robert Gates unveiled a new drive to cut $100 billion of the military's huge overhead costs and spend the money on troops and weapons upgrades.

The Pentagon's chief weapons buyer, Ashton Carter, this week singled out the Northrop plane as a "perfect example" of the military's problems, telling reporters, "It's on a path to be non-affordable."

Details of the agreement were still being worked out, but the savings could amount to hundreds of millions of dollars over the lifetime of the two programs, Lieutenant General David Deptula, the Air Force deputy chief of staff for intelligence, surveillance and reconnaissance, told reporters.

"It makes a lot of sense," Deptula said, noting the agreement was the first time the two services had worked together in a substantial way on separate major weapons.

He said a joint working group would identify ways to eliminate duplicate efforts and step up savings, including development of a common ground station that could eventually be used to control other unmanned planes.

Simply basing the Navy and Air Force planes at the same air bases would save millions of dollars in the shorter term, said Vice Admiral Jack Dorsett, the deputy chief of naval operations for information dominance.

Joint training, maintenance, logistics and data requirements could result in additional significant savings over time, including reducing the need for spares.

The deal is unique among the services, which often fight to maintain separate programs under their own control, and clearly reflects growing concern about costs at a time when defense spending is flattening out after years of double digit growth.

Virginia-based defense consultant Jim McAleese said the program was facing increased scrutiny by Pentagon budget officials, especially given the high cost of the sophisticated sensors being developed for the Navy version.

"This goes right to the very heart of the secretary's directive," McAleese said. "They're doing the right thing."

Dorsett said the move would not lead to more purchases of Navy planes, but would make use of the planes more efficient.

Officials said the deal did not reflect any "blurring" of the lines between the two services, noting that the different versions of the plane were developed to meet specific needs for surveillance over land and sea.

Northrop said the two versions of the plane, which first flew in 1998, were already about 78 percent common, but common control systems, work stations and communications would increase that percentage in coming years.

The RQ-4 aircraft used by the Air Force, Navy and NASA, has conducted more than 1,600 combat flights and logged 33,000 combat flight hours. The planes have collected over 600,000 images from Iraq and Afghanistan, while also providing data for natural disasters, like the Haiti earthquake earlier this year.

(Reporting by Andrea Shalal-Esa; Editing by Tim Dobbyn)