The US Army is working on a ground-based "sense-and-avoid" capability for its fleet of unmanned aircraft, a senior service official says.

"Right now the army is focused on ground-based sense-and-avoid. We are the lead for that under the OSD [Office of the Secretary of Defense] UAS [unmanned aircraft systems] task force," says Viva Austin, army product director for unmanned aircraft airspace integration concepts.

While ground-based sense-and-avoid started as a near-term effort to allow the army's unmanned aircraft to fly inside the US national airspace, it is now apparent that it will be used side-by-side with airborne sense-and-avoid when that technology is eventually developed, she says.

A prototype of the new ground radar-based system was being tested in El Mirage, California, but has since been shut down. But there is still some additional testing under way at the Dugway proving grounds in Utah, Austin says. She adds that the experiment was successful and that funding is now available to install the system on five General Atomics Aeronautical Systems MQ-1C Gray Eagles.

 Gray Eagle UAS - US Army

© US Army

Those aircraft will start to be fielded in fiscal year 2013, Austin says, and should be complete by the start of fiscal year 2014 to support training.

The army will establish radar-monitored corridors into restricted airspace for the Gray Eagles to transit to their training ranges. But for air-traffic at large, the corridors will be completely transparent, and only army controllers will be aware that such radar-monitored columns exist.

"It's an operational volume," Austin says. "But it doesn't mean anybody else has to stay out of it."

The first Gray Eagle corridor will be set up at Fort Hood in Texas, followed by Fort Riley in Kansas.

While currently the system is using radar to provide traffic separation, it is designed to be an open-architecture construct. In the future, it could pull in data from the Automatic Dependent Surveillance-Broadcast (ADS-B) transponder system for example, Austin says.

Eventually, the army will expand the system to cover a wider geographic area.

For airborne sense-and-avoid, the US Air Force and US Navy have the lead. Work is being done to try to miniaturise the technology for eventual use on the AAI RQ-7 Shadow UAS, she says. The army would use that technology when it is more mature.

The UAS is already slated to use the Ku-band tactical common data-link and the army is looking at potentially adding a new synthetic aperture radar to the Shadow, says Lt Col Scott Anderson, product manager for ground maneouvre. The army's special operations troops also experimented with a signals intelligence package in January, while he says the service is also looking to replace the type's current engine.

Source: Flight International