New Ground-Based System Provides Radar-Like Coverage In Rockies


The FAA has installed a stopgap system in Colorado that allows air traffic controllers to track aircraft in remote, mountainous regions where radar can’t reach, while waiting for the NextGen satellite-based ADS-B system to become operational in 2013. “The new system, called Wide-Area Multilateration, lets us see aircraft we couldn’t see before due to the rugged terrain,” said FAA Administrator Randy Babbitt. “It improves the safety and efficiency of those flights and saves time and money for passengers and operators.” The Colorado Department of Transportation estimates an average of 75 aircraft are delayed each day in the region between November and April. The WAM system, which went online Sept. 12, uses a network of about 20 small sensors deployed in remote areas. The sensors send out signals that are received and sent back by aircraft transponders. The precise location of aircraft is determined by triangulating the time and distance measurements of those signals. Controllers can see these aircraft on their screens as if they were radar targets.

The sensors are deployed around four airports: Yampa Valley-Hayden, Garfield County Regional-Rifle, Steamboat Springs and Craig-Moffat County, in an area that has a bustling tourist economy, especially during the ski season. “The demand for flights into western Colorado airports has increased dramatically over the past decade,” said Travis Vallin, Aeronautics Division Director for the Colorado DOT. “It was clear that we needed to do something innovative and cost-effective in order to enhance capacity and safety which improves the positive economic impacts that airports on the western slope have on the local, regional, and statewide economy.” The system, developed by Sensis, is the first multilateration system accepted into the National Airspace System by the FAA for the separation of en route aircraft by air traffic controllers. It will also provide important information for search-and-rescue missions. Once ADS-B is operational, WAM will serve as a backup in the event of a GPS outage. The FAA will operate and maintain the system, and will monitor its effectiveness to determine further deployment.