Definition
The section of the Federal Aviation Regulations that requires aircraft operating in most controlled airspace to be equipped with, and to use, Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment that meets specified performance standards. It defines where ADS-B Out is required, the technical equipment standards that must be met, and the limited circumstances under which an aircraft may operate in that airspace without it.
Plain English
This is the rule that tells you where you must have working ADS-B Out equipment installed and turned on. It covers Class A, Class B, Class C, most of Class E above 10,000 feet, and certain other airspace. If you fly into that airspace, your aircraft has to be broadcasting its position electronically the way the rule requires.
Context Anchor
Seen in airspace equipment requirements, especially when checking what equipment is required before operating in Class A airspace or other controlled airspace.
Derivation
‘14 CFR’ means Title 14 of the Code of Federal Regulations — the title that contains all federal aviation rules. ‘Part 91’ is the part covering general operating and flight rules for civil aircraft. ‘Section 91.225’ is the specific numbered rule within that part. Reading the citation as ‘title, part, section’ makes it easy to locate in the regulations.
Why Pilots Care
Compliance ensures legal access to Class A airspace and provides ATC with accurate position data for safe separation.
Intuition Check
Do not read this as a handbook page or chapter number. It is the exact location of a federal aviation rule that pilots are responsible for following.
Example Sentence 1
Before flying into the Class B airspace, the pilot verified the aircraft’s ADS-B Out installation met the requirements of 14 CFR part 91, section 91.225.
Example Sentence 2
A pilot checks the aircraft logbooks to confirm the ADS-B Out installation satisfies 14 CFR part 91, section 91.225.