Definition
The section of the U.S. Code of Federal Regulations that contains the general operating and flight rules for civil aircraft within the United States. It covers areas such as right-of-way, minimum safe altitudes, equipment requirements, instrument flight procedures, and pilot responsibilities for most non-commercial flying.
Plain English
The main rulebook every pilot flies under. It tells you the basic dos and don'ts of operating an aircraft in the United States.
Context Anchor
You will see 14 CFR part 91 in FAA handbooks, regulations, checklists, and instructor discussions whenever the legal rules for operating a flight are being referenced.
Derivation
CFR stands for Code of Federal Regulations, the body of rules issued by U.S. federal agencies. Title 14 is the title that covers Aeronautics and Space, and within it, Part 91 holds the general flight rules. So '14 CFR part 91' is simply the address of those rules: Title 14, Part 91.
Why Pilots Care
Pilots must follow these rules for every flight; they provide the foundation for safe operations and violations can lead to enforcement action or accidents.
Intuition Check
Do not think of “part 91” as a kind of airplane, license, or training level. It is a section of federal law that sets operating rules for flights.
Example Sentence 1
Most flight instruction and personal flying is conducted under 14 CFR part 91.
Example Sentence 2
14 CFR part 91 requires pilots to maintain proper right-of-way when two aircraft approach the same airport.