(b) The notice, review, and approval requirements set forth in this part do not apply to airports with restrictions as specified in 49 U.S.C. App. 2153(a)(2)(C):
(1) A local action to enforce a negotiated or executed airport aircraft noise or access agreement between the airport operator and the aircraft operator in effect on November 5, 1990.
(2) A local action to enforce a negotiated or executed airport aircraft noise or access restriction the airport operator and the aircraft operators agreed to before November 5, 1990.
(3) An intergovernmental agreement including airport aircraft noise or access restriction in effect on November 5, 1990.
(4) A subsequent amendment to an airport aircraft noise or access agreement or restriction in effect on November 5, 1990, where the amendment does not reduce or limit aircraft operations or affect aircraft safety.
(5) A restriction that was adopted by an airport operator on or before October 1, 1990, and that was stayed as of October 1, 1990, by a court order or as a result of litigation, if such restriction, or a part thereof, is subsequently allowed by a court to take effect.
(6) In any case in which a restriction described in paragraph (b)(5) of this section is either partially or totally disallowed by a court, any new restriction imposed by an airport operator to replace such disallowed restriction, if such new restriction would not prohibit aircraft operations in effect on November 5, 1990.
(7) A local action that represents the adoption of the final portion of a program of a staged airport aircraft noise or access restriction, where the initial portion of such program was adopted during calendar year 1988 and was in effect on November 5, 1990.
(c) The notice, review, and approval requirements of subpart D of this part with regard to Stage 3 aircraft restrictions do not apply if the FAA has, prior to November 5, 1990, formed a working group (outside of the process established by 14 CFR part 150) with a local airport operator to examine the noise impact of air traffic control procedure changes. In any case in which an agreement relating to noise reductions at such airport is then entered into between the airport proprietor and an air carrier or air carrier constituting a majority of the air carrier users of such airport, the requirements of subparts B and D of this part with respect to restrictions on Stage 3 aircraft operations do apply to local actions to enforce such agreements.
(d) Except to the extent required by the application of the provisions of the Act, nothing in this part eliminates, invalidates, or supersedes the following:
(1) Existing law with respect to airport noise or access restrictions by local authorities;
(2) Any proposed airport noise or access regulation at a general aviation airport where the airport proprietor has formally initiated a regulatory or legislative process on or before October 1, 1990; and
(3) The authority of the Secretary of Transportation to seek and obtain such legal remedies as the Secretary considers appropriate, including injunctive relief.