Definition
A federal regulation that places legal responsibility on the pilot in command to determine whether the aircraft is in a condition for safe flight, and requires the pilot in command to discontinue the flight if unairworthy mechanical, electrical, or structural conditions occur.
Plain English
This rule says the pilot in command — not the mechanic, not the owner, not the dispatcher — is the one legally on the hook for deciding the aircraft is safe to fly. If something breaks or fails in a way that makes the aircraft unsafe, the pilot must stop the flight.
Context Anchor
You will see this cited in preflight, airworthiness, and pilot responsibility discussions, especially when deciding whether an aircraft may legally and safely be flown.
Derivation
CFR stands for Code of Federal Regulations — the organized collection of U.S. federal rules. Title 14 covers Aeronautics and Space. Part 91 contains the general flight rules that apply to most civilian flying. The numbers after the part (91.7) point to a specific section, and the letter in parentheses (b) points to a specific paragraph within that section. So '91.7(b)' is just an address: it tells you exactly where to find this rule in the regulations.
Why Pilots Care
This regulation places direct legal responsibility on the pilot for airworthiness decisions, making preflight checks a required duty rather than optional practice.
Analogy
A legal citation is like an address. “14 CFR part 91, section 91.7(b)” tells you exactly where to find this rule in the federal aviation regulations.
Intuition Check
Do not read “part” here as an aircraft part. In this citation, “part” means a major division of the federal aviation regulations, and “section” means the specific rule inside that division.
Example Sentence 1
Under 14 CFR part 91, section 91.7(b), the pilot in command made the call to cancel the flight after discovering a fuel leak during preflight.
Example Sentence 2
After discovering a structural issue on the ground, the pilot applied 14 CFR part 91, section 91.7(b) and cancelled the flight.