Juneau International Airport Using Sensis WAM for Separation of Approach Aircraft

The Juneau WAM system uses multilateration to provide controllers at the Anchorage Air Route Traffic Control Center (ARTCC) with high accuracy, high availability surveillance of aircraft and helicopters, enabling ATC-provided radar separation and traffic advisory services to pilots operating in the Juneau airspace. The WAM system also provides a source of surveillance data for Traffic Information Services-Broadcast (TIS-B) being launched in Southeast Alaska by the FAA Surveillance and Broadcast Services (SBS) ADS-B Program. The mountainous terrain and limited infrastructure around Juneaus airport make existing long range radar ineffective below 10,000 feet Mean Sea Level (MSL), and the deployment of additional gap-filler radar systems is financially impractical. To improve safety of flights at Juneau, the FAA requested a WAM system to cover the airspace roughly 40 miles west, 10 miles south and 20 miles north of the airport. Sensis deployed a WAM system in the mountains surrounding Juneau International Airport, as directed by the FAA, providing controllers with improved situational awareness of all flights in the area from 200 feet Above Ground Level (AGL) at the airport to 20,000 feet MSL in the surrounding airspace. Due to the remote location of some sensors, communication between the sensors and the target processor is accomplished using a variety of communications systems, including leased digital data system circuits, FAA-supplied microwave links and Juneau Police microwave links. Sensis WAM uses multiple low-maintenance, non-rotating sensors to triangulate aircraft location based on transponder signals and to provide air traffic controllers with precise aircraft position and identification information, regardless of weather conditions. With a higher update rate and greater positional accuracy than traditional radar, Sensis WAM provides effective surveillance for increased safety, capacity and efficiency of airspace and airports. With its advanced processing techniques, Sensis multilateration uses the minimal number of sensors for a less complex, lower lifecycle cost solution. Additionally, every sensor deployed by Sensis also supports Automatic Dependent Surveillance Broadcast (ADS-B). The certification of the second Sensis WAM system for separation of flights in the NAS further demonstrates that wide area multilateration is a cost-effective, high-performance alternative to traditional radar in mountainous environments, said John Jarrell, vice president and general manager of Sensis Air Traffic Systems. In Juneau, the system had to overcome significant terrain and weather challenges to meet the FAAs stringent performance requirements for separation services. This was achieved due to Sensis WAMs use of multiple non-rotating sensors that are low power and highly flexible in supporting diverse communications systems.