49 U.S.C. § 46501

In this chapter— (1) “aircraft in flight” means an aircraft from the moment all external doors are closed following boarding— (A) through the moment when one external door is opened to allow passengers to leave the aircraft; or (B) until, if a forced landing, competent authorities take over responsibility for the aircraft and individuals and property on the aircraft. (2) “special aircraft jurisdiction of the United States” includes any of the following aircraft in flight: (A) a civil aircraft of the United States. (B) an aircraft of the armed forces of the United States. (C) another aircraft in the United States. (D) another aircraft outside the United States— (i) that has its next scheduled destination or last place of departure in the United States, if the aircraft next lands in the United States; (ii) on which an individual commits an offense (as defined in the Convention for the Suppression of Unlawful Seizure of Aircraft) if the aircraft lands in the United States with the individual still on the aircraft; or (iii) against which an individual commits an offense (as defined in subsection (d) or (e) of article I, section I of the Convention for the Suppression of Unlawful Acts against the Safety of Civil Aviation) if the aircraft lands in the United States with the individual still on the aircraft. (E) any other aircraft leased without crew to a lessee whose principal place of business is in the United States or, if the lessee does not have a principal place of business, whose permanent residence is in the United States. (3) an individual commits an offense (as defined in the Convention for the Suppression of Unlawful Seizure of Aircraft) when the individual, when on an aircraft in flight— (A) by any form of intimidation, unlawfully seizes, exercises control of, or attempts to seize or exercise control of, the aircraft; or (B) is an accomplice of an individual referred to in subclause (A) of this clause.