((a)) ** .—** Except as provided in subsection (b) of this section and , a person may operate a civil subsonic turbojet aircraft with a maximum weight of more than 75,000 pounds that is imported into the United States after , only if the aircraft—

((1)) complies with the stage 3 noise levels; or

((2)) was purchased by the person importing the aircraft into the United States under a legally binding contract made before .

((b)) ** .—** The Secretary of Transportation may provide an exemption from subsection (a) of this section to permit a person to obtain modifications to an aircraft to meet the stage 3 noise levels.

((c)) ** .—** In this section, an aircraft is deemed not to have been imported into the United States if the aircraft—

((1)) was owned on , by—

((A)) a corporation, trust, or partnership organized under the laws of the United States or a State (including the District of Columbia);

((B)) an individual who is a citizen of the United States; or

((C)) an entity that is owned or controlled by a corporation, trust, partnership, or individual described in subclause (A) or (B) of this clause; and

((2)) enters the United States not later than 6 months after the expiration of a lease agreement (including any extension) between an owner described in clause (1) of this subsection and a foreign carrier.