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ADS-B

Frequently Asked Questions (FAQs)

Equip ADS-B FAQ

General
Why is the FAA transitioning away from radar and towards ADS-B technology?
What are the ADS-B rules?
What will make me compliant to fly into ADS-B rule airspace?
Can I fly under IFR in non-ADS-B airspace if my aircraft is not equipped with ADS-B?
Can I get a one-time deviation from the requirement?
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?
ADS-B provides altitude, aircraft flight ID and vertical air speed. Will it also furnish horizontal air speed?
When will ADS-B services be available in my area?
When do I have to equip?
If I fly in airspace that does not require a transponder, will I still be able to fly there without ADS-B Out?
What is the difference between ADS-B Out and ADS-B In?
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 Mexico?
ADS-B Out
Does the final rule mandate ADS-B Out only?
How will the ADS-B Out rule affect aircraft operators?
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)?
Will the information broadcast by ADS-B Out be encrypted for security purposes?
ADS-B In
What are ADS-B In broadcast services?
What equipment is required to receive and display ADS-B In?
How are FAA broadcast services different from other traffic and weather advisory information?
ADS-B In allows operators to get traffic and data-linked geographical weather for free. Is it similar to XM weather?
Does TIS-B broadcast primary radar?
Is FIS-B free? Is TIS-B free?
How do existing traffic display systems integrate with ADS-B?
Can I install only ADS-B In?
Is weather information broadcast on 1090ES?

General

Why is the 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 Mexico 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.

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What are the ADS-B rules?

The FAA published Federal Regulation 14 CFR 91.225 and 14 CFR 91.227 in May 2010. The final rule dictates that effective January 1, 2020, aircraft operating in airspace defined in 91.225 are required to have an Automatic Dependent Surveillance – Broadcast (ADS-B) system that includes a certified position source capable of meeting requirements defined in 91.227. These regulations set a minimum performance standard for both the ADS-B transmitter and the position sources integrated with the ADS-B equipment.

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What will make me compliant to fly into ADS-B rule airspace?

See the information on the Equip ADS-B Installation page

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Can I fly under IFR in non-ADS-B airspace if my aircraft is not equipped with ADS-B?

The requirements of the ADS-B rule apply only to the airspace defined in 14 CFR 91.225, regardless of whether or not the operation is conducted under VFR or IFR. It's an airspace rule and does not apply to any type of operation outside defined airspace.

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Can I get a one-time deviation from the requirement?

Pilots/operators using aircraft that do not meet ADS-B Out equipage or performance requirements may request an authorization to deviate from the rule to access ADS-B Out rule airspace.

The FAA has developed the ADS-B Deviation Authorization Preflight Tool (ADAPT) to manage these authorization requests.

In order to be considered for an ADS-B deviation authorization with ADAPT, requests must meet the following criteria:

  • Aircraft must be equipped with an operational transponder and operational altitude encoder (e.g., Mode C)
  • Request submitted no more than 24 hours before flight
  • Request submitted no less than 1 hour before flight

Please note: The FAA will not issue in-flight authorizations to operators of non-equipped aircraft, nor will air traffic control (ATC) facilities accept requests for these types of authorizations by telephone.

For more information on ADAPT, please visit our ADAPT information page.

Also, please reference the Statement of Policy for Authorizations to Operators of Aircraft that are Not Equipped with Automatic Dependent Surveillance–Broadcast Out Equipment.

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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 the FAA and to aircraft operators within 23 years of implementation.

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ADS-B provides altitude, aircraft flight ID and vertical air speed. Will it also furnish horizontal air speed?

In fact, ADS-B reports two kinds of altitudes: barometric and geometric. Barometric or pressure altitude is the one pilots know best – this is the altitude that is displayed on the altimeter in the aircraft. Geometric altitude is calculated by GPS (Global Positioning Satellites) as the height of the aircraft above the earth ellipsoid. These two altitudes are not the same, but having both allows for applications that require one or the other as an altitude source and provides a means of verifying correct pressure altitude reporting from aircraft.

ADS-B does not report vertical or horizontal airspeed. Instead, ADS-B reports horizontal and vertical velocity relative to the Earth. This velocity is useful for air traffic control functions and ADS-B applications. Airspeed can be provided by other aircraft sensors.

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When will ADS-B services be available in my area?

Please refer to our interactive ADS-B airspace and coverage map for information on ADS-B coverage in the airspace around your home and other locations you may fly.

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When do I have to equip?

The requirement for ADS-B equipage is here. As of January 1, 2020, ADS-B Out equipment is required to operate in the airspace defined in 14 CFR 91.225. If you never fly into ADS-B-designated airspace, then there is no requirement to equip. Please refer to our decision tree to help determine if you need to equip.

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If I fly in airspace that does not require a transponder, will I still be able to fly there without ADS-B Out?

For the most part, ADS-B Out is required in the same airspace where transponders are required. However, to be sure of the regulatory requirements it is best to check 14 CFR 91.225 for ADS-B-designated airspace and 14 CFR 91.215 for transponder-designated airspace.

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What is the difference between ADS-B Out and ADS-B In?

ADS-B Out refers to an aircraft broadcasting its position and other information. ADS-B In refers to an aircraft receiving the broadcasts and messages from the ground network such as TIS-B and FIS-B. ADS-B In is not mandated by the ADS-B Out rule. If an operator chooses to voluntarily equip an aircraft with ADS-B In avionics, a compatible display is also necessary to see the information. Refer to AC 20-165B for information on ADS-B OUT and AC 20-172B on ADS-B In installation and certification.

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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.

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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.

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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.

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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. Line-of-sight range to a radio is typically 150 nautical miles or greater.

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How did implementation of ADS-B affect the airspace in the Gulf of Mexico?

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.

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ADS-B Out

Does the final rule mandate ADS-B Out only?

Yes, only ADS-B Out is mandated, and only within certain airspace. Title 14 CFR 91.225 defines the airspace within which these requirements apply.

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How will the ADS-B Out rule affect aircraft operators?

As of January 1, 2020, when operating in the airspace designated in 14 CFR 91.225 (outlined below) you must be equipped with ADS-B Out avionics that meet the performance requirements of 14 CFR 91.227.

Under the rule, ADS-B Out performance is required to operate in:

  1. Class A, B, and C airspace.
  2. Class E airspace within the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface.
  3. Class E airspace at and above 3,000 feet MSL over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles.
  4. Within 30 nautical miles of those airports identified in 14 CFR part 91, Appendix D. Otherwise known as the Mode C veil.

The ADS-B Out rule does not apply in the airspace defined in items 2 and 4 above for any aircraft not originally certificated with an electrical system or that has not subsequently been certified with such a system installed, including balloons and gliders. For additional requirements for using the exception for item 4, please refer to CFR 91.225 section (d) for the requirements.

Please refer to "What are the ADS-B rules?" for more information.

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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 interactive map to look at the location of ADS-B rule airspace at your home base and where you fly.

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Will the information broadcast by ADS-B Out be encrypted for security purposes?

ADS-B data can be received by any aircraft, vehicle, or ground station equipped to receive ADS-B. No encryption is specified. For more information on ADS-B Privacy, please visit the Privacy ICAO Address program page.

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ADS-B In

What are FAA ADS-B In broadcast services?

ADS-B In pilot cockpit advisory services consist of Flight Information Service-Broadcast (FIS-B) and Traffic Information Service-Broadcast (TIS-B). These are free services transmitted automatically to aircraft equipped to receive ADS-B In.

FIS-B provides a broad range of textual/graphical weather products and other flight information to the general aviation community. FIS-B is only available on the 978MHz Universal Access Transceiver (UAT) equipment. FIS-B includes the following:

  • Airmen's Meteorological Conditions (AIRMET)
  • Significant Meteorological Conditions (SIGMET) and Convective SIGMET
  • Aviation Routine Weather Reports (METAR)
  • Non-Routine Aviation Weather Reports (SPECI)
  • NEXRAD (regional and CONUS)
  • Notice to Airmen (NOTAM) Distant and Flight Data Center
  • Pilot Reports (PIREP)
  • Status of Special Use Airspace (SUA)
  • Terminal Area Forecasts (TAF) and their amendments
  • NOTAM – textual Temporary Flight Restrictions (TFRs)
  • Graphical TFRs
  • Winds & Temperature Aloft
  • TIS-B Service Status
  • Lightning strikes
  • Turbulence
  • Icing, Forecast Potential (CIP/FIP)
  • Cloud tops
  • Graphical-AIRMET
  • Center Weather Advisory
  • Temporary Restricted Areas (TRAs)**
  • Temporary Military Operations Areas (TMOAs)**

** Available NAS-wide in the summer of 2020

TIS-B is an advisory-only service available to both 1090ES and UAT equipment users. TIS-B increases pilots' situational awareness by providing traffic information on all transponder-based aircraft within the vicinity of the ADS-B In equipped aircraft receiving the data.

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What equipment is required to receive and display ADS-B In?

ADS-B In requires a receiver complying with either a 1090 MHz Technical Service Order TSO-C166b or 978 MHz Technical Service Order TSO-C154c, along with a processing system and cockpit display. Some aircraft require a display that conforms to ADS-B Technical Service Order TSO-C195b. The advisory circular for ADS-B In is AC 20-172B.

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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.

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ADS-B In allows operators to get traffic and data-linked geographical weather for free. Is it similar to XM weather?

Yes. ADS-B's Flight Information Services-Broadcast (FIS-B) provides all the aviation weather products available with an XM basic subscription, and more. In fact, at no subscription cost to the user, ADS-B FIS-B also provides many of the products available from the mid-to-high-tier XM subscription services.

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Does TIS-B broadcast primary radar?

For tracks that are initiated with secondary radar, TIS-B will update the track if there is a momentary loss of secondary and only the primary is available. For surface service volumes, TIS-B uplinks primary-only tracks because vehicles operating on airport surfaces may not be equipped with transponders or ADS-B Out.

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Is FIS-B free? Is TIS-B free?

TIS-B is a free service available to aircraft operators equipped with ADS-B Out and ADS-B In. FIS-B is available free to any operator with the ability to receive and display the data that is broadcast on the Universal Access Transceiver (UAT) or the 978 MHz link.

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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.

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Can I install only ADS-B In?

To receive ADS-B In services from the ground network, aircraft must broadcast valid ADS-B Out messages that indicate their ADS-B In capability. Aircraft with "In" only may "piggy back" off another aircraft receiving ADS-R and TIS-B services, but this will result in a partial picture of the traffic.

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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.

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This page was originally published at: https://www.faa.gov/nextgen/programs/adsb/faq/