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5 Of Your Most Common ADS-B Questions, Answered

Today we're answering some of the most common ADS-B (Automatic Dependent Surveillance-Broadcast) questions we get from readers. Check them out, and if you want to learn more about ADS-B, sign up for our National Airspace System course here.

1) Where do I need ADS-B?

If you're looking for regulatory guidance for when ADS-B "Out" is required, FAR 91.225 has your answer. 91.225 lists terminal environments where ADS-B is required, in addition to broader ADS-B rules like requirements for Class B & C airspace.

In general, ADS-B Out is required in the same places where Mode-C or Mode-S transponders are required.

There are exceptions, however, such as the ADS-B requirement over the Gulf of Mexico. According to the regs, ADS-B Out is required in "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."


2) Why ADS-B?

ADS-B Provides a precise position of your aircraft to ATC, as well as other aircraft that are equipped with ADS-B In.

ADS-B is also functional on the ground, helping controllers maintain safe and efficient ground operations, especially at busy airports.


3) ADS-B In Vs. Out?

ADS-B "In" is a data link sending weather and traffic information into your cockpit. This data is transmitted from ground stations as well from other aircraft.

ADS-B "Out" refers to the data leaving your plane, going to air traffic controllers and to other pilots in the sky.

ADS-B "Out" is the only equipment that's required by the FAA, however, many aircraft are equipped with both.


4) Can I fly in 'ADS-B airspace' even if I don't have ADS-B Out?

The FAA does grant temporary exceptions to the normal ADS-B Out regulations. In order to access ADS-B airspace without the proper equipment, you need to submit a request through the ADS-B Deviation Authorization Preflight Tool.

If your plane has an operational transponder (Mode A, Mode C, or Mode S) and you submit your request no more than 24 hours before your flight but no less than 1 hour you are eligible to request a temporary exemption; though air traffic control reserves the right to deny requests on a workload basis.


5) What do I get out of installing ADS-B?

On the surface, the accuracy of this new system results in more efficient routing, reduced traffic separation requirements, and increased aircraft/threat awareness for pilots.

But, when you dive deeper into the features of ADS-B, and specifically ADS-B In, you see the incentives for installing it in your aircraft. Pilots who install ADS-B In have access to FIS-B and TIS-B data.

With FIS-B, you can see up-to-date weather products such as METARs, TAFs, and Nexrad radar with no subscription cost.

And with TIS-B traffic, you are able to see other planes around you on your instrument panel, or on an EFB application. This is incredibly helpful when you're navigating busy airspace.


Want to learn more about how ADS-B works, and what it does for you in the cockpit? Sign up for our National Airspace System course here. We've dedicated an entire chapter to how ADS-B works, and how you can use it to make safer, more efficient flights.

Nicolas Shelton

Nicolas is a private pilot from Southern California. He is currently studying at Purdue University, where he is working on advanced pilot ratings. You can reach him at

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