Legal Interpretations
Osmundson-Southern Air 2014
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U.S. Department of Transportation Federal Aviation Administration JU.~ 3.0 2014 Don Osmundson Vice President of Flight Operations Southern Air Inc.
117 Glover A venue Norwalk, CT 06850
Dear Mr. Osmundson,
Office of the Chief Counsel 800 Independence Ave., S.W .
Washington, D.C. 20591 This is in response to your letter asking about the flight, duty, and rest provisions applicable to a pilot to whom 14 C.F.R. § 121.525(c) applies. Specifically, you ask whether the provisions of§ 121.521 would be applicable to the pilot when he is operating on a 3-pilot crew and whether the provisions of§ 121.523 would apply when the pilot is operating on a 4-pilot crew.
Supplemental air carriers conducting overseas and international supplemental operations may elect, pursuant to § 121.513, to comply with the flight time limitations of§ 121.515 and§§ 121.521through121.525 (commonly referred to as the "international rules"). 1 Normally, a crew of two pilots and one additional airman is subject to the flight, duty, and rest provisions of§ 121.521 while a crew of three or more pilots and additional airmen is subject to the provisions of§ 121.523.
However, if a pilot serves in more than one type of flight crew, that pilot is subject to the provisions of§ 121.525. Subsection 12 l.525(c) applies to a pilot who is "scheduled for duty aloft for more than 20 hours in two-pilot and additional flight crewmember crews in 30 consecutive days or whose assignment in such a crew is interrupted more than once in any 30 consecutive days by assignment to a crew consisting of three pilots and an additional flight crewmember." This subsection states that pilots to which it is applicable are subject to the flight time limitations of§ 121.521.
You ask us to assume that the pilot in your question is subject to the provisions of § 121.525(c). Because the plain text of§ 12l.525(c) states that a pilot subject to its provisions must be scheduled under § 121.521 , the pilot in your question must be scheduled under§ 121.521 regardless of whether he is on a 3-pilot or a 4-pilot crew. We note, however, that this applies only to pilots working on mixed operations subject to § 121 .525(c). Pilots on a four-pilot crew who are not working on mixed operations subject to§ 121.525 would be subject to the provisions of§ 121.523.
1 See J4 C.F.R. § 121.513. In order to answer your question, we will assume that the carrier employing the pilot in your question is eligible to operate under the international rules and has made an election to operate under these rules.
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We appreciate your patience and trust that the above responds to your concerns. If you need further assistance, please contact my staff at (202) 267-3073. This response was prepared by Alex Zektser, Attorney, Regulations Division of the Office of the Chief Counsel, and coordinated with the Air Transportation Division of Flight Standards Service.
ury Assistant Chief Counsel for In ational Law, Legislation, and Regulations, AGC-200
Retrieved from ecfr.gov on July 18, 2026.