The pilot in command (PIC) of an aircraft is the person aboard an aircraft who is ultimately responsible for its operation and safety during flight. This would be the captain in a typical two- or three-pilot aircrew, or "pilot" if there is only one certificated and qualified pilot at the controls of an aircraft. The PIC must be legally certificated (or otherwise authorized) to operate the aircraft for the specific flight and flight conditions, but need not be actually manipulating the controls at any given moment. The PIC is the person legally in charge of the aircraft and its flight safety and operation, and would normally be the primary person liable for an infraction of any flight rule.
The strict legal definition of PIC may vary slightly from country to country. The International Civil Aviation Organization (ICAO) definition is: "The pilot responsible for the operation and safety of the aircraft during flight time."[1]
In Annex 2, "Rules of the Air", under par. "2.3.1 Responsibility of pilot-in-command", ICAO declares:[1]
The pilot-in-command of an aircraft shall, whether manipulating the controls or not, be responsible for the operation of the aircraft in accordance with the rules of the air, except that the pilot-in-command may depart from these rules in circumstances that render such departure absolutely necessary in the interests of safety.
In Annex 2, par. "2.4 Authority of pilot-in-command of an aircraft", ICAO adds:[1]
The pilot-in-command of an aircraft shall have final authority as to the disposition of the aircraft while in command.
ICAO Annex 2, par. 2.3.1, specifically empowers the PIC to override any other regulation in an emergency, and to take the safest course of action at his/her sole discretion. This provision mirrors the authority given to the captains of ships at sea, with similar justifications. It essentially gives the PIC the final authority in any situation involving the safety of a flight, irrespective of any other law or regulation.