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United States Department of TransportationUnited States Department of Transportation

Fact Sheet – Automatic Dependent Surveillance-Broadcast (ADS-B)

For Immediate Release

August 13, 2014
Contact: Paul Takemoto or Tammy Jones
Phone: (202) 267-3883

What is ADS-B?
NextGen is delivering benefits to pilots, airlines and the flying public now through ADS-B, one of the most important, underlying technologies in NextGen.

The Next Generation Air Transportation System or NextGen is the modernization of the nation’s air traffic control infrastructure providing air travelers a faster, safer and more efficient way to fly while reducing aviation’s carbon footprint. ADS-B is the satellite-based surveillance system that air traffic controllers are using now to monitor and safely separate aircraft.

The FAA has completed the baseline installation of a nationwide network of radio stations that provide ADS-B coverage– including areas not covered by radar, such as the Gulf of Mexico and portions of Alaska. Of the 230 air traffic facilities across the country, more than 100 are currently using this system to separate traffic. It is expected to be connected and operating at all 230 facilities by 2019.

ADS-B significantly enhances air traffic surveillance capabilities. With ADS-B, controllers can see aircraft with much greater precision, accuracy and reliability. Pilots flying aircraft equipped with a certain type of ADS-B technology are able to see what controllers see – other aircraft in the sky around them – as well as bad weather and terrain. They also receive flight information, including pilot reports and flight restrictions.

How does it work?
Aircraft equipped with ADS-B avionics that broadcast their position – called ADS-B Out – send their precise, GPS-derived location to radio stations on the ground. The radio stations process the GPS-derived data and sends that information to controller screens, where controllers are able to see information such as aircraft speed, altitude and identity. Precise aircraft position is also broadcast to aircraft equipped with ADS-B In technology, which provides pilots through cockpit displays, information on where they are in relation to other aircraft, as well as information about bad weather and terrain.

What are the benefits of ADS-B? 
Moving from ground-based radar to satellite-based ADS-B is a major leap in air traffic control technology. Radar is safe – the FAA maintains the world’s safest aviation system – but has limitations. Radar signals degrade over distance, cannot penetrate through solid objects such as mountains, and the fastest radar updates every 4.7 seconds.  By contrast, the satellite signals used with ADS-B do not degrade over distance, provide better visibility around mountainous terrain and allows equipped aircraft to update their own position once a second with better accuracy.

The FAA first deployed ADS-B in southwest Alaska, equipping general aviation aircraft with cockpit displays that showed pilots where they were in relation to bad weather, terrain and other aircraft. The improved situational awareness for pilots translated directly to significant safety benefits; the accident rate for those equipped aircraft in southwest Alaska fell by approximately 47 percent.

The improved accuracy, integrity and reliability of satellite signals also means controllers will be able to safely reduce the mandatory separation between aircraft, which is currently between three to five miles depending on the phase of flight. The safe reduction in separation standards will increase capacity and efficiency in the nation’s skies.

With ADS-B – along with a host of satellite-based procedures being rolled out as part of NextGen – aircraft are able to fly more directly from Point A to Point B, saving time and money while reducing fuel burn. As just one example, United Parcel Service in partnership with the FAA equipped/upgraded its aircraft with ADS-B avionics. Other airlines that have equipped some of their fleets with ADS-B include United, USAir and JetBlue.

ADS-B will also reduce the risk of runway incursions. Pilots, controllers and ground vehicle operators will be able to avoid accidents by being able to see the precise location of other aircraft and properly equipped ground vehicles moving on airport surfaces, even at night or during bad weather.

Why adopt ADS-B?
Radar technology dates back to World War II.  Primary radar, which reflects off the aircraft surface, occasionally has problems discriminating airplanes from objects like migratory birds and rain (secondary radar interacts with aircraft transponders to receive aircraft identity, speed, altitude, etc.). In addition, both primary and secondary radars are large structures that are expensive to deploy and maintain, and require the agency to lease land on which to situate them. By contrast, ADS-B ground stations are comparatively inexpensive, and significantly smaller, requiring very little real estate.

Who installed the radio stations?
Exelis Corporation (formerly ITT Corporation) was selected in August 2007 as the prime contractor for the successful deployment of the ADS-B radio infrastructure.

When will everyone be required to use ADS-B?
A final rule issued by the FAA in May 2010 mandates that all aircraft flying in certain controlled airspace be equipped with ADS-B Out avionics beginning January 1, 2020. The agency published an Advisory Circular (AC 20-165) that provides installation guidance for ADS-B Out systems.

In December 2009, standards were approved for ADS-B avionics. Approval of the minimum operational performance standards (MOPS) and related Technical Standard Orders (TSOs) gives vendors and operators assurance that the equipment meeting those standards will fulfill the requirements of the ADS-B rule.