HELICOPTER IN-FLIGHT TRACKING SYSTEM (HITS) FOR THE GULF OF MEXICO

Helicopters and other low-altitude air traffic over the Gulf of Mexico operate without the benefit of radar surveillance due to the location and range of existing onshore radar installations. The National Aeronautics and Space Administration (NASA) Ames Research Center (ARC) is sponsoring deployment and testing of a prototype Helicopter In-flight Tracking System (HITS) in a portion of the Gulf of Mexico offshore area. Using multilateration principles, HITS determines the location and altitude of all transponder-equipped aircraft without requiring changes to current Mode A, C or S avionics. Best capabilities are provided in the “primary” coverage area, which is bounded by a polygon enclosing the 21 HITS ground sensors. HITS accuracy is highest in this 7,000 nmi2-footprint region, and surveillance is provided to aircraft above 100 ft MSL, allowing helicopters to be tracked onto the helideck of most offshore platforms. Transponder-equipped aircraft are also tracked in the “extended” coverage region, an 8,725 nmi2-footprint area that forms a border around the primary coverage area. In the extended coverage region, surveillance accuracy is somewhat decreased and minimum coverage altitudes are larger. In addition to multilateration, HITS provides surveillance reports for aircraft equipped for Automatic Dependent Surveillance – Broadcast (ADS-B), a new technology under development by the Federal Aviation Administration (FAA), in both the primary and extended coverage regions. The U.S. Department of Transportation (DOT) Volpe National Transportation Systems Center (Volpe Center) is supporting NASA in managing HITS installation and operation, and in evaluating the system's effectiveness. Sensis Corporation is supplying, installing and maintaining the HITS ground system. Project activities are being coordinated with the FAA and offshore helicopter operators. Flight-testing in the Gulf begins in mid-2002. This paper describes the HITS project — specifically, the system equipment (architecture, remote sensors, central processing site, and communications equipment) and system performance (accuracy, coverage, and reliability).