SafeFlight 21

SafeFlight 21 (SF21) is a joint government-and-industry effort to improve the safety, efficiency, and capacity of the National Airspace System using a variety of technologies to provide real-time traffic information to both air traffic controllers and flight crews. The Volpe Center provides extensive technical and management expertise to SF21, which is evaluating and developing new communications, navigation, and surveillance technologies for use on the airport surface, in terminal areas surrounding major airports, in the en route domain (between destinations), and in oceanic operations.

Volpe's accomplishments since the program's inception in 1998 include: deployment of a surface surveillance system in Louisville; deployment of a terminal area surveillance system in Memphis; development of a prototype surface automation system; and development, deployment, and evaluation of two prototype oceanic surveillance systems in the Gulf of Mexico. The Volpe team plays a major role in requirements definition, system engineering, software development, site engineering, and analysis of surface and terminal surveillance systems.

Memphis International Airport. For the FAA, Volpe designed and installed the SF21 Surveillance Server, which fuses surface surveillance radar information with transponder-based multilateration tracks to provide seamless coverage of Memphis' airport operations area; this system was the prototype fusion server for the ASDE-X system being deployed at 32 airports. The Center also evaluated the "outer ring" deployment (see illustration).

Gulf of Mexico. The Gulf of Mexico airspace has two major operating regions and user groups: low-altitude offshore (less than 7,000 ft), utilized by general aviation; and high-altitude oceanic (over 18,000 ft), utilized by air carriers. Both regions suffer significant inefficiencies due to the lack of continuous surveillance during instrument flight rules operations. Provision of surveillance in the offshore region is hindered by its low-altitude nature, which makes coverage by conventional radars economically infeasible. Significant portions of the oceanic sectors are inaccessible to shore-based sensors, as they are beyond line-of-sight.

Under joint National Aeronautics and Space Administration (NASA) and FAA sponsorship, the Volpe Center developed and evaluated prototypes for two emerging surveillance technologies--Wide Area Multilateration (WAM) and Automatic Dependent Surveillance--Broadcast (ADS-B). These technologies are low cost (in comparison with current radars) and were deployed on offshore platforms. Nine flight test campaigns were conducted using fixed-wing and rotary-wing aircraft.

MEMPHIS OUTER RING TERMINAL-AREA MULTILATERATION SURVEILLANCE SYSTEM: This system extends surveillance well beyond the surface to 60 nmi from the airport and an altitude in excess of 45,000 ft. Multilateration determines the location of an aircraft by interrogating the aircraft's transponder. The transponder's reply is measured by an array of sensors on the ground that computes aircraft identification and position.

The WAM system demonstrated the ability to track helicopters down to platform helidecks--an important factor in expediting search and rescue operations. The ADS-B system provides surveillance coverage of approximately the northern 70 percent of the Gulf airspace, and overlaps coverage of Mexican radars on the Yucatan peninsula. This capability can enable aircraft separations to be reduced from approximately 100 nmi to 5 nmi--a dramatic capacity increase that would eliminate multi-hour delays during busy periods. The FAA Joint Resources Council has begun to deploy the WAM system and is considering ADS-B deployment.