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Top 10 Things You Need to Know about ADS-B

Quick Tips and Information for GA Aircraft

Source: FAA Safety Briefing, Mar/Apr 2017, By Jennifer Caron

ads b facts graphic

With the fast approaching January 1, 2020 deadline to equip with ADS-B Out, pilots and owners want to learn more.

Here are 10 things you need to know.

1. ADS-B Out is Mandated, Not ADS-B In

Only ADS-B Out is mandated, and only within certain airspace. Starting January 1, 2020, you must be equipped with ADS-B Out to fly in the airspace where a Mode C transponder is required today. ADS-B Out greatly improves your visibility to other aircraft by broadcasting your aircraft’s position to other aircraft equipped with ADS-B In and to air traffic control (ATC).

Go to to find the airspace where ADS-B will be required near you. For more information on the mandate, see

You can also integrate ADS-B Out with ADS-B In avionics and displays. ADS-B In equipage is not required by the mandate, but it’s a great addition to your situational awareness arsenal. ADS-B In can receive two types of free broadcast services — one for traffic information services (TIS-B), and another for flight information services (FIS-B).

The traffic picture displayed in your cockpit includes position information reported by other aircraft on ADS-B Out, as well as traffic information relayed from the FAA ground system (TIS-B).

In addition, you can benefit from graphical weather via FIS-B. FIS-B also broadcasts text-based advisories and aeronautical information such as Notices to Airmen, Temporary Flight Restrictions, pilot reports, and the status of Special Use Airspace. These features are only available via broadcasts on 978Mhz.

2. You Are Required to Operate Your ADS-B Out Transmitter at All Times

All ADS-B equipped aircraft are required to operate their ADS-B Out transmitter at all times including while on the surface of the airport — 14 CFR section 91.225(f ).

Why? ADS-B Out works by regularly broadcasting position, velocity, and identification information to ATC, and other aircraft, to improve situational awareness at all times — on the ground and in the air. Increasingly, air traffic systems and ADS-B In products are being developed with alerting logic that depends on your ADS-B Out broadcast.

3. Portable ADS-B Out Units Are Not An Option

Portable ADS-B Out avionics (also known as “suitcase” units) are not an approved option for ADS-B Out.

Here’s why. First, unlike installed equipment where antennas are appropriately positioned — the GPS antenna sits atop your aircraft, and the ADS-B antenna sits on the bottom — portable units use a suction-cup antenna on the window or the glare shield of the plane. That’s where it needs to be to get a usable GPS signal, but that position puts it in a prime spot to obstruct your view, especially if you’re flying VFR.

Additionally, the portable system wiring potentially hampers controls and instruments and, if the antenna is not in just the right place, the signal suffers. In that case, ATC and other aircraft with ADS-B In can’t see you.

Second, portables can transfer from aircraft to aircraft. That sounds like a great idea at first, but that’s where mistakes can become an issue. On a portable, you have to input your aircraft’s N-number — correctly. If you’re off by just one digit, then the ID in your flight plan won’t match up with the ID transmitted by your portable unit. A high number of call sign mismatch incidents happen for this very reason. To learn more, read “What’s In a Name?”.

Portable units are acceptable for use with your tablet only for the ADS-B In (ADS-B receiver) feature.

ADS-B equipment

4. Uncertified Equipment? Check Your Airworthiness Certificate

You may only install an uncertified transmitter on amateur-built aircraft and light-sport aircraft with experimental airworthiness certificates if it meets the performance requirements of Technical Standard Order (TSO)-C166b or TSO-C154c.

For S-LSA owners, the ADS-B equipment must meet the performance requirements in TSO–C166b; or TSO–C154c, and the installation (i.e., alteration) must be performed in accordance with an applicable consensus standard and authorized by the aircraft’s manufacturer.

Additionally, you cannot install uncertified equipment, including uncertified transmitters on any aircraft with a standard airworthiness certificate. Uncertified ADS-B transmitters that do not meet the performance requirements of an ADS-B TSO will not be permitted to operate in airspace requiring ADS-B after January 1, 2020. ATC cannot use the data from transmitters that do not meet most of the performance requirements of 14 CFR section 91.227 — this means ATC cannot provide flight-following services or separation services to these aircraft.

For GPS equipment, you may install an uncertified GPS on amateur-built and light-sport aircraft with experimental airworthiness certificates. As stated above, uncertified equipment must meet the performance requirements of a GPS TSO.

Again, you cannot install uncertified equipment, including an uncertified GPS on aircraft with standard airworthiness certificates. Additionally, position sources that do not meet the performance of a GPS TSO will not comply with 14 CFR section 91.227 and will not be permitted to operate in airspace requiring ADS-B.

Amateur built aircraft and light-sport aircraft owners wishing to install an uncertified device that meets the performance requirements of TSO-C166b or TSO-C154c should ensure they obtain a letter from the equipment manufacturer, stating the device meets the performance requirements of either TSO-C166b or TSO-C154c.

More on this topic will be covered in future issues of FAA Safety Briefing. The bottom line is that the equipment option you choose must meet the performance requirements, and it must function properly!

5. Always Keep Your ADS-B Installation Instructions

Here’s a quick tip. Always keep the installation instructions from the supplier, including the statement of compliance, in your aircraft records just in case you have any service problems.

6. You May Not Have To Buy a New Position Source Suitable for ADS-B

Avionics vendors offer reasonably-priced, built-in approved position sources, such as WAAS GPS receivers, and package them with ADS-B transmitters.

7. Make Sure Your ADS-B Equipment and GPS Equipment is an Approved Pairing

Any GPS receiver used as an ADS-B position source must be an “approved pairing” with the ADS-B transmitter. A GPS receiver must be compatible with the installed ADS-B transmitter.

Mixing and matching GPS receivers with ADS-B transmitters in the field (accomplished via field approval) is not permitted unless the equipment was shown to be compatible via a previous certification effort with the FAA (for example, a Supplemental Type Certificate).

There are many options, but only certain combinations of GPS receivers and ADS-B transmitters function properly. Contact the equipment manufacturer if you are not sure which GPS receivers are approved for your ADS-B system.

ADS - B graphic how it works

8. The Airspace You Fly Reveals the Type of Equipment You Need

If you’re flying in Class A airspace, you will need a 1090 megahertz extended squitter (ES) transmitter. You will also need a 1090ES ADS-B Out transmitter if you operate outside the United States in airspace where ADS-B is required.

Always flying below Class A, and not internationally where ADS-B is required? Then you have a choice between a 1090ES or a Universal Access Transceiver (UAT) transmitter.

The majority of Class E airspace is outside of ADS-B required airspace. In particular, airspace that starts at 700 / 1,200 feet above the surface up to 10,000 feet mean sea level (MSL), except from the Gulf of Mexico shoreline out to 12 nautical miles offshore. You can still be above 10,000 MSL, but below 2,500 above ground level (AGL) and not be required to have ADS-B.

For a detailed look at the ADS-B requirements per airspace, go to

9. The ADS-B Out Mandate Applies to Foreign Operators

The United States’ ADS-B-Out mandate will affect foreign aircraft operators. Starting January 1, 2020, all aircraft, including foreign-registered aircraft that operate in, or fly through the United States, must be equipped with ADS-B Out to operate in ADS-B required airspace in the United States. The ADS-B Out equipment must comply with the performance requirements found in 14 CFR sections 91.225 and 91.227.

10. Beat the Rush and Install ADS-B Out Now

As we have noted in other articles, 2020 sounds like a long way off. From a repair shop’s point of view, though, 2020 is just around the corner. As we draw closer to the deadline, avionics shops may become inundated with appointments from owners who waited until the last minute. You may be unable to get a service date before the deadline, and you will not be allowed to fly in ADS-B required airspace until your aircraft is ADS-B Out equipped.

Now is also a good time to install, so you can take advantage of the FAA’s $500 rebate program for installing ADS-B on certain types of single-engine aircraft.

And don’t forget — after the install, you have to fly into rule airspace to validate that your ADS-B Out equipment works before you get the rebate.

Jennifer Caron is an assistant editor for FAA Safety Briefing. She is a certified technical writer-editor, and is currently pursuing a Sport Pilot Certificate.

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