Definition
Part 91 is the section of Title 14 of the Code of Federal Regulations (14 CFR Part 91) that contains the General Operating and Flight Rules for civil aircraft operating in the United States. It covers basic flight rules, equipment requirements, maintenance responsibilities, preflight actions, right-of-way rules, instrument flight procedures, and similar baseline regulations that apply to nearly all flights, including private (non-commercial) operations.
Plain English
Part 91 is the rulebook that covers everyday flying — the basic rules every pilot follows when not flying for hire. It sets out things like who has the right of way, what equipment must work, and how to operate under instrument flight rules.
Context Anchor
Seen in FAA handbooks when a pilot must know which rule governs what to do next, such as during a communication or navigation system failure.
Derivation
The U.S. federal aviation regulations are organized by numbered 'parts.' Part 91 is simply the 91st numbered section of Title 14 of the Code of Federal Regulations. The number itself has no special meaning — it is just the location in the rulebook where general operating rules live.
Why Pilots Care
Knowing the applicable rules under Part 91 helps a pilot decide what actions remain legal and safe when systems fail.
Intuition Check
“Part 91” does not mean a physical part of the airplane. Here, “part” means a numbered section of federal aviation rules.
Example Sentence 1
A private pilot flying friends to a nearby airport on the weekend is operating under Part 91.
Example Sentence 2
The instructor reminded the student that most personal flights are conducted under Part 91 rules.