What is ADS-B?
ADS-B is one of the most important, underlying technologies in the FAA’s plan to transform air traffic control from the current radar-based system to a satellite-based system. ADS-B is bringing the precision and reliability of satellite-based surveillance to the nation’s skies.
How does it work?
ADS-B uses GPS signals along with aircraft avionics to transmit the aircraft’s location to ground receivers. The ground receivers then transmit that information to controller screens and cockpit displays on aircraft equipped with ADS-B avionics.
What are the benefits of ADS-B?
ADS-B for the first time allows pilots to see what controllers see: other aircraft in the sky around them. Pilots are also able to see – and avoid – bad weather and terrain, and receive flight information such as temporary flight restrictions. The improvement in situational awareness for pilots greatly increases safety.
The improved accuracy, integrity and reliability of satellite signals over radar means controllers will be able to safely reduce the mandatory separation between aircraft. This will increase capacity in the nation’s skies.
ADS-B also provides greater coverage, since ADS-B ground stations are so much easier to place than radar. Remote areas without radar coverage, like the Gulf of Mexico and parts of Alaska, are now covered by ADS-B.
Relying on satellite signals instead of ground-based navigation aids also means aircraft fly more directly from Point A to Point B, saving time and money while reducing fuel burn. United Parcel Service voluntarily equipped approximately 100 of its aircraft with ADS-B avionics, knowing that it will recoup its investment by saving time and money on flights to and from its Louisville hub.
ADS-B will also reduce the risk of runway incursions. Pilots and controllers will be able to see the precise location of aircraft and properly equipped ground vehicles moving on the ground – even at night or during heavy rainfall.
Why adopt ADS-B?
Radar technology dates back to World War II. Radar occasionally has problems discriminating airplanes from migratory birds and rain “clutter.” ADS-B, which receives data directly from transmitters rather than scanning for targets like radars, does not have a problem with clutter.
Radars are also large structures that take up a lot of space, are expensive to deploy and maintain, and require the FAA to lease the land upon which they are situated. ADS-B ground stations take up only 20 square feet, including the perimeter fence. Ground stations are the size of mini-refrigerators. Under the terms of its contract with ITT Corp., the company that is installing the ground stations, the FAA will only pay for ADS-B signals. The equipment will be owned and maintained by ITT.
Who’s installing the ground stations?
ITT Corporation was selected in August 2007 to be the prime contractor for the ADS-B ground stations. ITT will build, install and maintain the nationwide network. The FAA will pay “subscription charges” to the company, just as the agency today buys telecom services from telecommunications companies. This will reduce costs and give the agency greater flexibility.
Under the terms of its contract, ITT must have ground stations in place to cover the entire nation by 2013.
As the ADS-B infrastructure expands, companies are likely to use ADS-B capabilities to offer even more services to private pilots and airlines.
What about aircraft avionics?
The agency issued a proposed rule asking for industry comment on the avionics necessary for implementing ADS-B across the national airspace system. Under the proposal, operators would equip their aircraft with avionics based on the airspace in which they plan to operate.
The FAA is currently reviewing comments and will issue a final rule soon. The final rule will specify performance standards for ADS-B avionics. The marketplace will then take over, as manufacturers build avionics that must meet those standards.
Where is ADS-B being rolled out?
ADS-B has been deployed at the following key sites:
- The Gulf of Mexico. Air traffic controllers at the Houston en route center are now able to separate aircraft tracked by radar and ADS-B. This brings significant improvements in safety and efficiency since radar coverage does not extend beyond 200 miles over water.
- Louisville. The system is being used by controllers in the tower at Louisville International Airport and at the Louisville Terminal Radar Approach Control (TRACON) facility. Louisville was chosen as a key site in part because of UPS’ voluntarily participation in the program.
- Philadelphia. Controllers in the Philadelphia area now have the capability to use ADS-B to track and separate aircraft. ADS-B coverage in Philadelphia extends 60 nautical miles out from Philadelphia International Airport and approximately 10,000 feet up. It also covers the surface area and the approach corridors to the runways. Philadelphia was selected in part because UPS has equipped some of its aircraft with ADS-B and a large amount of their operations are conducted there.
- South Florida. Controllers are not yet using ADS-B to separate aircraft in that region, but general aviation aircraft equipped with ADS-B avionics now have weather and traffic information broadcast to the cockpit for free. ITT has installed 11 ground stations in the region.