Definition
A federal regulation titled 'Responsibility and authority of the pilot in command.' It states that the pilot in command is directly responsible for, and is the final authority as to, the operation of the aircraft. It also permits the pilot in command to deviate from any rule in Part 91 to the extent required to meet an in-flight emergency, and requires a written report to the FAA Administrator upon request when such a deviation occurs.
Plain English
This is the rule that says the captain of the aircraft is in charge and carries the responsibility for what happens. If a real emergency makes it necessary, the pilot is allowed to break the normal rules to handle it -- but may have to explain in writing afterwards.
Context Anchor
Seen in emergency procedures, pilot responsibility discussions, and FAA references to the legal authority of the pilot in command.
Derivation
CFR' stands for Code of Federal Regulations -- the official collection of U.S. government rules. 'Part 91' is the section covering general operating and flight rules for civil aircraft, and '§' is the standard symbol for 'section.' So '14 CFR part 91, § 91.3' simply points to a specific numbered rule within that body of regulations.
Why Pilots Care
It legally protects pilots who take necessary emergency actions and clarifies who holds final decision authority.
Intuition Check
Do not read this as permission to ignore rules whenever it is convenient. It applies to the pilot in command’s responsibility and, in emergencies, to deviations only as far as needed to handle the emergency.
Example Sentence 1
Under 14 CFR part 91, § 91.3, the pilot in command declared an emergency and descended below the assigned altitude to escape severe icing.
Example Sentence 2
The instructor reminded the student that 14 CFR part 91, § 91.3 gives the pilot in command final say over every flight decision.