FAA considers commercial satellites for traffic control

An air traffic control experiment in Alaska could extend traffic coverage via commercial satellites.

Late last year, the Federal Aviation Administration awarded a $2 million contract to General Dynamics Corp. to investigate the feasibility of using commercial satellites in its Capstone Communications and Control System.

Since 2001, FAA has been trying a new tracking approach in Alaska, in which each airplane transmits its own location using the Global Positioning System.

The Automatic Dependent Surveillance-Broadcast technology differs from the usual way of tracking aircraft with ground-based radar.

Proponents claim ADS-B gives more details about airspeed, altitude and direction. FAA is looking for ways to coordinate flights in high-traffic areas with more precision.

An ADS-B unit on an aircraft can send out an information packet each second, whereas radar grabs location information only once every six seconds, Capstone program manager John Hallinan said.

The initial rollout of Capstone, using ADS-B technology, covered portions of southeast Alaska via 12 satellite ground stations. But because Alaska has large stretches of mountainous, barely populated terrain, most aircraft there would not be trackable. A ground station covers up to 150 square miles, and more than 200 ground stations would be needed for the whole state.

Supplemental satellites

'It would be way too costly to provide a ground-based service infrastructure,' Hallinan said. 'What we think is probably viable is using satellite capability to supplement it in remote airspace.'

General Dynamics will investigate how well a satellite data communications service from Iridium Satellite LLC of Arlington, Va., can transmit small packets of location data to and from each craft.

Iridium has 66 low-earth-orbit communications satellites circling the planet.

General Dynamics also will research other aspects of satellite coverage, including latency of data communications and ways of keeping costs down, such as having multiple aircraft share information.

'We need to see whether ADS-B data can be sent from the aircraft up to a satellite and dropped back down and [still be] sufficiently timely to be used by air traffic control,' Hallinan said.

About the Author

Joab Jackson is the senior technology editor for Government Computer News.

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