Definition
The section of Title 14 of the Code of Federal Regulations (14 CFR Part 91) that sets the technical performance and equipment standards for Automatic Dependent Surveillance-Broadcast (ADS-B) Out systems used in U.S. airspace. It defines what an aircraft's ADS-B Out equipment must transmit, how accurately, and to what technical standards in order to be considered compliant.
Plain English
It's the rule that spells out exactly what an aircraft's ADS-B Out gear has to send, and how good that signal has to be, for the aircraft to count as properly equipped.
Context Anchor
You will see section 91.227 mentioned in operating-rule discussions for airspace such as Class A, where certain aircraft equipment must meet specific FAA requirements before entry.
Derivation
Section comes from a Latin word meaning “to cut.” Regulations are divided into numbered “sections,” like cut-apart pieces of a larger rulebook. Here, 91.227 identifies one specific rule inside Part 91, which covers general operating rules.
Why Pilots Care
An aircraft must meet this rule to operate legally in most controlled airspace; failure to comply can result in enforcement action or denial of ATC services.
Intuition Check
Do not read “section 91.227” as an area of airspace or a part of the airplane. It is a numbered FAA rule that sets equipment performance requirements.
Example Sentence 1
Before buying a used aircraft, the pilot confirmed that its ADS-B Out installation met the performance standards of section 91.227.
Example Sentence 2
During the preflight briefing the instructor reminded the student that section 91.227 applies to most flights above 10,000 feet.