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An ADS-B Out transmitter alone will not be sufficient to meet the requirements outlined in 14 CFR 91.227. To comply with the requirements for the ADS-B Rule, the aircraft must be equipped with a Version 2 ADS-B Out transmitter and a compatible GPS Position Source. There are two ADS-B avionics systems available:

  • Mode S transponder-based (1090 MHz) ADS-B equipment must meet the performance requirements of Technical Standard Order TSO-C166b. For aircraft operating above FL180 (18,000 feet) or internationally, you must be equipped with a Mode S-transponder-based ADS-B transmitter. For aircraft operating below 18,000 feet and within U.S. airspace, you must be equipped with either a Mode S transponder with Extended Squitter or
  • Universal Access Transceiver (UAT) equipment must meet the performance requirements of TSO-C154c. UAT equipment provides the ability to receive traffic and weather data provided by the FAA ADS-B network.

The FAA recommends a WAAS GPS that is compliant with TSO-C145 or TSO-C146. These units are readily available for general aviation and provide sufficient performance to meet the 14 CFR 91.227 requirements. Avionics vendors offer stand-alone GPS receivers and package them with ADS-B transmitters or with GPS Navigators. Mixing and matching GPS systems with ADS-B transmitters in the field is not permitted unless the equipment pairing was shown to be compatible via a previous certification effort with the FAA (for example, an STC). Be sure to contact your manufacturer if you are unsure which GPS systems are approved for your ADS-B transmitter.

The Installation Approval for ADS-B OUT Systems memo explains the FAA's policy regarding installation of ADS-B Out systems into civil aircraft.

Getting the Installation Right

It's important to know that incorrectly installed ADS-B equipment means that your aircraft does not comply with the ADS-B equipage rule. If you already have equipment installed, find out if your equipment is working properly. And if you're ready to make your installation appointment, explore some of the things you should know when selecting a shop to do the installation work, learn about some common problems that can occur during the installation, and know what to expect before accepting an installation in this FAA Safety Briefing article.

photos of ADS-B ground testing equipment

ADS-B ground testing equipment, as shown here, can verify all parameters are correct after an ADS-B installation.

The FAA is working with operators, manufacturers, and installers on eliminating common ADS-B installation errors. The most common issues associated with an ADS-B installation are:

  • Missing Barometric Pressure Altitude
  • Air/Ground Determination Issues
  • Flight ID issues including Missing Flight ID 3-letter identifier
  • Duplicate & Wrong ICAOs
  • Invalid Mode 3/A Code — Mitigation in place
  • Incorrect Emitter Category
  • Aircraft with Position Errors

For additional information, please read the technical paper (PDF) explaining the FAA's policy regarding alterations to aircraft for the installation of ADS-B equipment.

FAA Field Approval Guidance

Current policy allows for field approvals under specific conditions. An update to this memo is in progress.

To check if your installation complies with the rule, you can request:

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