The U.S. Army may cancel two of four unmanned aerial vehicles (UAVs) planned for its Future Combat Systems (FCS) in response to fears that the skies above tomorrow’s battlefield are getting too crowded with helicopters, drones and airborne munitions.

The fate of the aerial drones rests with officials who are studying the Army’s UAV needs, said Maj. Gen. Charles Cartwright, who manages the service’s $165 billion, top-priority FCS program.

This review also aims to determine whether giving four types of unmanned aircraft to each brigade will strain the troops’ ability to maintain them or needlessly weigh down the brigade with spare parts. FCS is intended to help create agile fighting forces with greatly reduced logistics needs.

The UAVs are key to the FCS concept, which also will equip each brigade with a squadron of armed reconnaissance helicopters. The program aims to increase battlefield sensors sixfold. But the concept originally was designed for battles in wide-open spaces, not the cities and mountain roads where U.S. troops have fought their largest battles in recent years.

Air and ground officers say the air above today’s battlefields is already too crowded, and adding more unmanned craft will increase the chances of deadly collisions.

The number of UAVs in use by the U.S. military has skyrocketed since the 2003 invasion of Iraq. Hard experience has shown that the skies above a battlefield, particularly in Baghdad and other cities, can rapidly become congested with UAVs and the many attack and transport helicopters flying at similar altitudes.

Moreover, ground forces that want to fire artillery or rockets must clear a segment of airspace so they do not shoot down friendly aircraft.

There has been at least one UAV-helicopter collision; in 2004, a hand-launched Raven drone collided with a Little Bird helicopter over Baghdad. No serious damage resulted, but the incident led the Army to tighten its airspace restrictions.

This has reduced UAV use. Last year, soldiers from the Army’s 3rd Infantry Division in Baghdad said they had all but abandoned the Raven because any unit wanting to fly it had to apply for clearance more than 24 hours in advance.

So the question is how to improve air traffic control in congested airspace. For starters, the Army is working to improve the clearance process, Paul Bogosian, the Army’s aviation procurement chief, said in April.

Bogosian also said the Army is trying to develop a common ground station for controlling UAVs, which will help manage the radio signals that guide the aircraft. One Army officer in Iraq said competing radio signals mean that only three Shadow UAVs can fly over Baghdad at a time.

And conflicting signals have boosted an accident-and-loss rate among Army UAVs that is “way too high,” Bogosian said. Another way to ease the congestion problem is to reduce the number of planned UAVs.

Current Army plans say each 3,200-soldier FCS brigade will carry four kinds of UAVs, one each for small units, companies, battalions and brigades. When married with ground sensors and robotic vehicles, the aerial sensors are intended to provide up-to-the-second information on the disposition of enemy forces.

The smallest one, the Class I Micro Air Vehicle, will be a 7-kilogram vertical-takeoff aircraft built by Honeywell. The largest will be Northrop Grumman’s helicopter-like Fire Scout, which can fly for 24 hours and will be operated by brigade-level units.

Three firms are bidding to build each of the middle-sized Class II and Class III UAVs. The Class II UAV can fly for two hours, and will be distributed to company-sized units. The Class III UAV, designed to fly up to six hours, will equip battalions.

Cartwright said both competitions are on hold while the Army reviews its UAV plan. The review also will examine whether the FCS UAVs would overlap with three others that the Army has in development or in service.

Besides the handheld Raven, built by AeroVironment, the service’s aviation command is buying the medium-sized Shadow UAV, built by AAI, and is pushing hard to field by 2009 the long-range armed Warrior, a modified version of the General Atomics’ Predator in widespread U.S. Air Force service.

The Army is creating a new UAV battalion within its aviation brigades, each to be equipped with 24 Warrior drones. Shadow and Warrior would remain in Army service for decades.

Boeing FCS program manager Dennis Muilenberg said the review has not yet stopped any of the UAV research and development efforts.

“We’re continuing to execute our plan,” Muilenberg said.

Still, the questions about the scope of the FCS UAV effort come amid growing pressure in the Pentagon and Congress to scale back the giant program, although service leaders publicly support the current plan.

The Iraq experience has revealed limitations of UAVs. U.S. troops reported that the low-flying Shadow’s engine noise has tipped off the insurgents, so they have come to rely much more on manned Air Force jets. F-16s equipped with targeting pods can provide surveillance over a wider area and much more quickly than slow-flying UAVs.

Comments: Greg Grant,