DEMONSTRATIONS of "free flight" for general-aviation aircraft are now under way as part of a larger evaluation of the USA's future air-traffic-management concept.

The trials involve a Cessna 401, equipped with avionics supplied by Magellan Systems and Arinc, and a ground-based free-flight evaluation system which was developed by Mitre for the US Federal Aviation Administration.

The free-flight concept will enable aircraft operators to select their preferred routes through US airspace, using the global-positioning system (GPS) for navigation, GPS positioning-reporting for surveillance and datalink for communication.

The Magellan/Arinc CNS-12 system in the Cessna is an integrated GPS/ datalink unit able to transmit position reports for automatic dependent surveillance (ADS) via Arinc's ACARS VHF datalink. In the free-flight trial, ADS reports have been transmitted from the Cessna to a workstation installed at the FAA's Kansas City, Missouri, air-traffic-control centre.

Also participating are Mooney light aircraft operated by the Florida Institute of Technology. These are equipped with displays showing the positions of other aircraft, including airliners, involved in the trial. Radar and ADS position data are uplinked to the Mooneys by Mitre datalink.

The first units, with Arinc datalink and GPS/ADS capability, are expected to be delivered in December, and will be upgraded later to incorporate navigation-management functions enabling the GPS to be used for en route and terminal-area navigation and non-precision approach.

Source: Flight International