FAA and the Colorado Department of Transportation have introduced wide-area multilateration (WAM) to allow air traffic controllers to track aircraft in remote and mountainous regions not covered by radar.
The system comprises a small network of sensors deployed in remote areas that send out signals received and sent back by aircraft transponders. FAA explains no other equipment is required. System computers determine the precise location of the aircraft by triangulating the time and distance measurement of those signals, and controllers are able to view the aircraft on their screens as if they were radar targets.
Colorado's transportation department is splitting the cost of WAM with FAA. The system on 12 September started initial operations at four small airports: Yampa Valley-Hayden, Craig-Moffat, Steamboat Springs and Garfield County Regional-Rifle. The state of Colorado paid for the equipment, physical site preparations, power and telecommunications for WAM while FAA is operating and maintaining the system.
FAA explains the mountains in those areas are home to ski resorts, but the terrain makes the use of radar impossible since radar signals cannot pass through solid objects.
Colorado's transportation department estimates the flight limitations are compounded by bad weather, which results in an average of 75 aircraft being delayed each day at the remote airports from November to April.
WAM is designed for near-term use as FAA deploys automatic dependent surveillance broadcast (ADS-B) by 2013. After that time WAM will serve as a backup in the event of a GPS outage.
Source: Air Transport Intelligence news
