If asked today for their views about automatic dependent surveillance-broadcast (ADS-B), many pilots might respond that it was developed to meet the unique needs of single-engine commercial operators in remote areas such as Alaska, where only minimal ATC services were available. Alternatively, it was aimed at helping freighter pilots best position themselves in inbound traffic streams during “rush hour” operations around freight hubs.

But fewer pilots would correctly identify ADS-B as a technology that the FAA plans to implement for virtually all aircraft, nationwide, by 2012. And also one that will eventually become the international standard, from general aviation to the major airlines. At the ICAO Air Navigation Conference in Montreal last September, the U.S. and all the world’s nations agreed to the international adoption of ADS-B as “the leading aviation safety means.”

Why ADS-B? Basically, it is because the system provides pilots with a continuous flight deck presentation of the position and intended movements of all other aircraft in the airspace around them, thereby dramatically increasing situational awareness and, as a consequence, safety. Importantly, the system will augment, not replace, air traffic control and TCAS.

At a recent NASA conference, Dr. Marc Buntin, en route and oceanic lead in
FAA’s Safe Flight 21 program, described the agency’s long-term strategy to establish nationwide ADS-B service. Buntin recognized the pioneering work accomplished in Alaska under the agency’s Capstone project, and also that performed by United Parcel Service at Louisville, Ky.

Buntin described the FAA’s approach to NAS-wide ADS-B coverage as one of building up “pockets of implementation” at points where the system can produce immediate user benefits, and then to slowly expand these until nationwide coverage is achieved by 2012. So far, these pockets are primarily centered on general aviation use, which is expected to offer early payback to aircraft owners. Of these, the highest-profile locations will be the Prescott, Ariz., and Daytona Beach, Fla. campuses of Embry-Riddle Aeronautical University (ERAU)–a move that has been strongly endorsed by AOPA, which regards ADS-B as a key safety technology for general aviation.

ERAU has ordered about 100 Garmin MX20 multifunction displays and associated DL90 ADS-B transponders for its training aircraft, with installations set to begin in the spring. Each location will also have an FAA-supplied ADS-B ground station, which will allow university staff to monitor the movements of all its aircraft. This is a capability never before available to a civil flight-training school. Installation of the ground stations, built by Sensis was under way at press time, and these were expected to be operational by this month.

This service will be particularly valuable at Prescott, which has much less low-level ATC radar coverage than Daytona Beach. Sean Jeralds, chair of ERAU flight training at Prescott, described ADS-B as having “phenomenal capability,” and said that “successful implementation in Arizona and Florida could convince the FAA to complete the installation of ground stations throughout the country.”

In fact, the recent ground station contract award to Sensis for expansion of the Alaska Capstone program included options for up to 1,000 stations, although it is estimated that the state requirements will not exceed 240. At the NASA conference, Dr. Buntin presented the FAA’s proposed ADS-B station network running from New Jersey to Florida, and stated that the agency was aiming for an initial operational capability by the end of this year. He noted that this initial configuration would be further expanded by state aviation authorities in Maryland and North Carolina, which have committed to funding four stations each, and also by NASA’s SATS (small aircraft transportation system) project.

Most of the East Coast stations will transmit and receive data over the FAA-developed Universal Access Transponder (UAT) format, which is optimized for general aviation use, although some will also offer airlines and other high-end users the internationally adopted, and more sophisticated, mode-S-based 1090ES (for “extended squitter”) format. Industry sources expect that eventually, multimode UAT/1090ES avionics units will probably become standardized.

Besides the East Coast stations, the FAA is also implementing a Gulf of Mexico ADS-B network, with five stations along the coast between Texas and Florida, three on offshore platforms in the Gulf, and two on Mexico’s Yucatan peninsula. These stations will bring high-accuracy, radar-like aircraft tracking to an area where lack of radar coverage has meant that ATC must fall back on procedural separations, which reduce capacity and create delays.

But the FAA is not alone in moving ahead with ADS-B. Officials at Eurocontrol, which has been evaluating the system for several years, are aiming for its mandatory installation in all aircraft by 2007, and state that more than 30 percent of their projected future safety and efficiency improvements depend on all aircraft using ADS-B in their airspace. Australia is now also implementing the system, which it sees as a lower-cost alternative to radar in the remote areas of the country. Australian ATC officials report routinely tracking ADS-B equipped UPS freighters and other airline jets over long distances and at high altitudes via its first system ground station on the country’s east coast.