Buying guide
ADS-B Out: when it is required in Europe and in the United States
Published November 13, 2026.
ADS-B Out is the equipment that broadcasts an aircraft's position, speed and identification to air traffic control and to other aircraft. Europe and the United States both require it, but for different aircraft and in different airspace, so the same aircraft can be compliant on one side of the Atlantic and not on the other. Below is what the official rules say and what to check before buying, especially an aircraft that will change continents.
What ADS-B Out is
In the FAA's definition, ADS-B Out is a function of the aircraft's avionics that periodically broadcasts its three-dimensional position and velocity and other required information. The same rule sets how accurate and how reliable that information must be.2
Who has to carry it
| United States (14 CFR § 91.225) | Europe (Regulation 1207/2011, Article 5) | |
|---|---|---|
| Which aircraft | Any aircraft flying in the airspace listed in the rule, with exceptions for aircraft never certified with an engine-driven electrical system | Aircraft with a maximum take-off mass over 5,700 kg or a maximum cruising true airspeed over 250 knots, whose individual certificate of airworthiness was first issued on or after June 7, 1995 |
| Where | Class A airspace; and below 18,000 ft in Class B and C, within 30 NM of the listed major airports up to 10,000 ft, and in Class E at and above 10,000 ft over the 48 contiguous states (excluding 2,500 ft and below above the surface) | On the flights covered by the regulation |
| Equipment | 1090 MHz extended squitter (DO-260B or later) in Class A; below 18,000 ft, 1090 MHz or UAT | ADS-B extended squitter, version 2, with position, velocity and integrity data; antenna diversity for these heavier or faster aircraft |
| Since | January 1, 2020 | December 7, 2020; June 7, 2023 for older aircraft under a retrofit programme set up before December 7, 2020 |
The US rule is the CFR edition of January 1, 2025.1 For Europe we read Regulation 1207/2011 in the version kept in UK law at the end of 2020, as published by the UK government; check the current EU text before relying on a detail.34 All aircraft covered by the European rule also need a Mode S transponder with the elementary capabilities of Annex II.3
What that means in practice
- A light trainer in Europe. A Diamond DA42 or a Cessna 172 is under 5,700 kg and slower than 250 knots, so the European ADS-B rule above does not cover it; the same aircraft flying into the busiest US airspace does need ADS-B Out.13
- A 1970s or 1980s jet in Europe. A Citation 500 or an early Citation II is faster than 250 knots, but its certificate of airworthiness was first issued before June 7, 1995, so the European ADS-B requirement does not apply to it by that criterion. In the United States it needs ADS-B Out to fly in Class A airspace.13
- A Bravo, or a late Ultra. A jet whose first certificate of airworthiness dates from June 7, 1995 or later is covered by the European rule and by the US rule; on an Ultra built around 1995, the date of that certificate decides.13
What to check before buying
- The date of the first certificate of airworthiness. In Europe, for heavier or faster aircraft, it decides whether ADS-B Out is required.3 Ask for it together with the serial number; the routine for checking both is in this post.
- The exact transponder and its standard. A listing that says "Mode S" does not say ADS-B. Ask for the model, the software and the standard it meets, and for the position source connected to it.12
- The installation paperwork. This part is our reading. Ask for the installation approval and the entry in the records; an ADS-B unit fitted without them is a cost waiting for the buyer.
- A change of continent. An aircraft that crosses the Atlantic may need equipment it never needed before. Check the rules of the airspace where it will fly, not where it is today.
- RVSM. In the United States, ADS-B Out is also one of the conditions of the route to RVSM without a separate approval, as we explain in the RVSM guide.
Sources
- FAA, 14 CFR § 91.225, ADS-B Out equipment and use (CFR edition of Jan. 1, 2025): govinfo.gov
- FAA, 14 CFR § 91.227, ADS-B Out equipment performance requirements (CFR edition of Jan. 1, 2025): govinfo.gov
- Commission Implementing Regulation (EU) No 1207/2011, Article 5, version retained in UK law: legislation.gov.uk
- Commission Implementing Regulation (EU) No 1207/2011, Annex II, version retained in UK law: legislation.gov.uk