The president and at least two-thirds of the board of directors and other managing officers of a national air carrier must be citizens of the United States.
"§41101. Requirement for a certificate
(a) General.—Except as provided in this chapter or another law—
(1) an air carrier may provide air transportation only if the air carrier holds a certificate issued under this chapter authorizing the air transportation;
(2) a charter air carrier may provide charter air transportation only if the charter air carrier holds a certificate issued under this chapter authorizing the charter air transportation; and
(3) an air carrier may provide all-cargo air transportation only if the air carrier holds a certificate issued under this chapter authorizing the all-cargo air transportation.
[...]
§41102. General, temporary, and charter air transportation certificates of air carriers
(a) Issuance.—The Secretary of Transportation may issue a certificate of public convenience and necessity to a citizen of the United States authorizing the citizen to provide any part of the following air transportation the citizen has applied for under section 41108 of this title:
(1) air transportation as an air carrier.
(2) temporary air transportation as an air carrier for a limited period.
(3) charter air transportation as a charter air carrier.
[...]
§41103. All-cargo air transportation certificates of air carriers
(a) Applications.-A citizen of the United States may apply to the Secretary of Transportation for a certificate authorizing the citizen to provide all-cargo air transportation. [...]
§41301. Requirement for a permit
A foreign air carrier may provide foreign air transportation only if the foreign air carrier holds a permit issued under this chapter authorizing the foreign air transportation.[...]" (Transportation Code (49 U.S.C. current through Pub. L. 117-49), §§ 41101, 41102, 41103 and 41301)
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"§ 204.2 Definitions.
As used in this part:  [...]
(c) Citizen of the United States  means: 
(1) An individual who is a citizen of the United States; 
(2) A partnership each of whose partners is an individual who is a citizen of the United States; or 
(3) A corporation or association organized under the laws of the United States or a State, the District of Columbia, or a territory or possession of the United States, of which the president and at least two-thirds of the board of directors and other managing officers are citizens of the United States, which is under the actual control of citizens of the United States, and in which at least 75 percent of the voting interest is owned or controlled by persons that are citizens of the United States. [...]" (Code of Federal Regulations, 14 C.F.R. (last amended on 10/06/2021) § 204.2)
Transportation Code (49 U.S.C. current through Pub. L. 117-49), §§ 41101, 41102 and 41103
Code of Federal Regulations, 14 C.F.R. (last amended on 10/06/2021) § 204.2
[<a href="http://uscode.house.gov/view.xhtml?req=granuleid%3AUSC-prelim-title49-subtitle7-partA-subpart2&saved=%7CZ3JhbnVsZWlkOlVTQy1wcmVsaW0tdGl0bGU0OS1zZWN0aW9uNDExMDM%3D%7C%7C%7C0%7Cfalse%7Cprelim&edition=prelim">Code</a>],[<a href="https://www.ecfr.gov/current/title-14/chapter-II/subchapter-A/part-204/subpart-A/section-204.2">Reg</a>]