ADS-B FAQ
- General
- Why is the FAA transitioning away from radar and towards ADS-B technology?
- What will make me compliant to fly into ADS-B rule airspace?
- What other surveillance solutions were examined for NextGen and what were the reasons for the decision to implement ADS-B over other alternatives such as Loran enhancement, ground station Mode C transceivers, or Mode S?
- What are the limitations on ADS-R (rebroadcast) coverage?
- What TSO versions are needed to comply with the ADS-B Out equipage rule?
- What is uncompensated latency?
- Ground Infrastructure
- What is the range of the ADS-B radio station?
- How did implementation of ADS-B affect the airspace in the Gulf of America?
- Is ADS-B service expansion possible?
- ADS-B Out
- What are the ADS-B Out requirements in U.S. sovereign airspace outside of the 48 contiguous states (Alaska, Hawaii, Guam, Puerto Rico, U.S. Virgin Islands, etc)?
- ADS-B In
- How are FAA broadcast services different from other traffic and weather advisory information?
- How do existing traffic display systems integrate with ADS-B?
- Is weather information broadcast on 1090ES?
General
Why is FAA transitioning away from radar and towards ADS-B technology?
ADS-B is an environmentally friendly technology that enhances safety and efficiency, and directly benefits pilots, controllers, airports, airlines, and the public. It forms the foundation for NextGen by moving from ground radar and navigational aids to precise tracking using satellite signals.
With ADS-B, pilots can see what controllers see: displays showing other aircraft in the sky. Cockpit displays also pinpoint hazardous weather and terrain, and give pilots important flight information, such as temporary flight restrictions.
ADS-B reduces the risk of runway incursions with cockpit and controller displays that show the location of aircraft and equipped ground vehicles on airport surfaces — even at night or during heavy rainfall. ADS-B applications being developed now will give pilots indications or alerts of potential collisions.
ADS-B also provides greater coverage since ground stations are so much easier to place than radar. Remote areas without radar coverage, like the Gulf of America and much of Alaska, now have surveillance with ADS-B.
Relying on satellites instead of ground navigational aids also means aircraft are able to fly more directly from Point A to B, saving time and money, and reducing fuel burn and emissions.
The improved accuracy, integrity and reliability of satellite signals over radar means controllers will be able to safely reduce the minimum separation distance between aircraft and increase capacity in the nation's skies.
What will make me compliant to fly into ADS-B rule airspace?
See the information on the Equip ADS-B Installation page
What other surveillance solutions were examined for NextGen and what were the reasons for the decision to implement ADS-B over other alternatives such as Loran enhancement, ground station Mode C transceivers, or Mode S?
The FAA determined the new surveillance system would need to supply these capabilities to lay the foundation for NextGen:
- Core Surveillance. Perform as well as or better than today's surveillance system, while also enabling multifunction capabilities. Deliver services cost-effectively.
- Cockpit Advisory Services. Provide traffic, weather, and database products to improve pilots' situational awareness and decision-making abilities.
- Cockpit Critical Services. Enable advanced cockpit display applications that would improve capacity by allowing aircraft to fly safely with improved efficiency and reduced spacing between aircraft.
In its analysis, the agency also considered the possibility of doing nothing and retaining all existing radar sites until 2035.
Two alternatives for ground and air-to-air surveillance services were considered along with ADS-B because they met two of the three above criteria (Loran, Mode S, and Mode C technologies did not). These were radar replacement and multilateration. Radar replacement could supply core surveillance and cockpit advisory services, but could not support air-to-air cockpit services and paid back only a fraction of its implementation costs in benefits. Multilateration did not support air-to-air applications. Only ADS-B supported all required and desired capabilities and was found to provide sufficient benefits to FAA and to aircraft operators within 23 years of implementation.
What are the limitations on ADS-R (rebroadcast) coverage?
ADS-R coverage is provided wherever an ADS-B Out- and ADS-B In-equipped aircraft is within range of an ADS-B ground station. Aircraft will not receive ADS-R if they are not appropriately equipped or within coverage of the ADS-B ground system.
What TSO versions are needed to comply with the ADS-B Out equipage rule?
Please refer to Advisory Circular 20-165B as well as TSO-C154c and TSO-C166b for current certification and installation standards for ADS-B Out.
What is uncompensated latency?
Uncompensated latency is any delay in the time lapse between calculating the aircraft position and broadcasting that information that cannot be compensated for in the avionics by extrapolating the position information of the target.
Ground Infrastructure
What is the range of the ADS-B radio station?
In general, the range would depend on your aircraft's altitude and any terrain that might block your line of site with the radio station. However, there are also practical limits due to transmitter power and receiver sensitivity.
How did implementation of ADS-B affect the airspace in the Gulf of America?
Before ADS-B, surveillance was not available in the Gulf at low altitudes or beyond 200 nautical miles from the coast. Now with ADS-B in place, air traffic control can provide 5-nautical mile separation to low-flying aircraft and to aircraft traversing the Gulf, provided the aircraft have certified ADS-B Out equipage.
Is ADS-B service expansion possible?
For airports not currently covered by ADS-B services, expansion is possible through private funding. The effort includes identifying ADS-B service requirements and completing agreements with the FAA and SBS service provider.
As an example, the Truckee Airport identified a need for improved operations. By utilizing their funds, they successfully expanded ADS-B coverage, further improving the safety and efficiency within the area. See their story: Truckee Airport ADS-B.
For more information, email ads-b@faa.gov.
What are the ADS-B Out requirements in U.S. sovereign airspace outside of the 48 contiguous states (Alaska, Hawaii, Guam, Puerto Rico, U.S. Virgin Islands, etc)?
ADS-B is required in Class A, B and C airspace within U.S. domestic airspace and all land mass regions of the U.S. as defined in 14 CFR 1.1 and it includes the states (contiguous and non-contiguous), U.S. possessions, or territories. Please view the Operations Of Aircraft Without Automatic Dependent Surveillance-Broadcast (ADS-B) Out In U.S. ADS-B Out Rule Airspace for full ADS-B requirements and the ADS-B airspace and coverage map to look at the location of ADS-B rule airspace at your home base and where you fly.
ADS-B In
How are FAA broadcast services different from other traffic and weather advisory information?
The main difference is that ADS-B In broadcast services do not require subscription or usage fees. If you choose to equip, ADS-B traffic, weather, and aeronautical information services are available to you free of charge.
How do existing traffic display systems integrate with ADS-B?
There are several multi-function displays on the market that interface with ADS-B. Some ADS-B avionics and traffic displays are produced by the same manufacturer. Before you finalize a purchase, check with an installer or avionics manufacturer to ensure that all of your equipment components will interface properly. Refer to AC 20-172B for information on ADS-B In installation and certification guidance.
Is weather information broadcast on 1090ES?
No. FIS-B provides weather data and it is only available on the UAT or 978MHz link due to bandwidth considerations.