Section 121.503 - Flight time limitations: Pilots: airplanes(a) A certificate holder conducting supplemental operations may schedule a pilot to fly in an airplane for eight hours or less during any 24 consecutive hours without a rest period during those eight hours.(b) Each pilot who has flown more than eight hours during any 24 consecutive hours must be given at least 16 hours of rest before being assigned to any duty with the certificate holder.(c) Each certificate holder conducting supplemental operations shall relieve each pilot from all duty for at least 24 consecutive hours at least once during any seven consecutive days.(d) No pilot may fly as a crewmember in air transportation more than 100 hours during any 30 consecutive days.(e) No pilot may fly as a crewmember in air transportation more than 1,000 hours during any calendar year.(f) Notwithstanding paragraph (a) of this section, the certificate holder may, in conducting a transcontinental nonstop flight, schedule a flight crewmember for more than eight but not more than 10 hours of continuous duty aloft without an intervening rest period, if- (1) The flight is in an airplane with a pressurization system that is operative at the beginning of the flight;(2) The flight crew consists of at least two pilots and a flight engineer; and(3) The certificate holder uses, in conducting the operation, an air/ground communication service that is independent of systems operated by the United States, and a dispatch organization, both of which are approved by the Administrator as adequate to serve the terminal points concerned.Doc. No. 6258, 29 FR 19218, Dec. 31, 1964; 30 FR 3639, Mar. 19, 1965, as amended by Amdt. 121-253, 61 FR 2613, Jan. 26, 1996