Northrop Grumman is developing a common autonomous airborne sense-and-avoid system for both the U.S. Air Force RQ-4B Global Hawk high-altitude long-endurance unmanned aircraft and its U.S. Navy RQ-4N Broad Area Maritime Surveillance (BAMS) derivative.

Originally the services were pursuing separate solutions for operating the aircraft in national airspace, but the Navy has announced its intention to award Northrop Grumman a sole-source contract to develop a common system that also will be scalable to medium-altitude unmanned aircraft.

The development effort will bring together work that was already under way on a sense-and-avoid system for Global Hawk and a "due regard" system for BAMS. "They have both put funds in a bucket, basically, that they have allocated to us," says George Guerra, Global Hawk vice president.

"For the Air Force we were continuing to look at what the opportunities were for a sense-and-avoid system, while the BAMS program actually proposed a due-regard system," he says. "What they did is say let’s go understand what systems you are looking at on the Air Force side and share with you what [the Navy] has done on due regard."

Guerra says Northrop Grumman was awarded a 5-6 month study earlier this year to understand the requirements of both services, how well the systems being studied would meet them, and to plan a way forward. "Our plan is to come out with a single system that satisfies the needs of both services," he said.

Under contract to the Air Force Research Laboratory (AFRL), Northrop Grumman has been flight-testing a multisensor autonomous see-and-avoid system on a Calspan-operated Learjet 25 acting as a surrogate for the Global Hawk. This includes electro-optical (EO) sensors and an air-to-air radar similar to that originally proposed for BAMS.

But the radar did not meet the BAMS requirements, and Northrop Grumman requested new proposals from suppliers. AFRL, meanwhile, contracted with Colorado Engineering to develop an active electronically scanned array specifically for sense-and-avoid.

The new radar has increased accuracy at longer range. A prototype is to fly in fiscal 2010.

Guerra says a similar joint effort is under way between the Air Force and Navy to combine the planned re-architecture of the Global Hawk ground segment, required to overcome obsolescence, with development of the mission control element for BAMS. Northrop Grumman planned to present its initial ideas on a common ground station to the services in late August.

Photo: Northrop Grumman