4. (1) Notwithstanding any other enactment or rule of law but subject to section 10, section 34 of the Act of 2000 as read with section 34B or 34C, as appropriate, of that Act, and section 37 of that Act as read with section 37R or 37S, as appropriate, of that Act, the competent authority shall, in accordance with the Aircraft Noise Regulation, this Act and the Act of 2000, have exclusive competence to impose, revoke, revoke and replace, or amend the terms of, an operating restriction.

(2) Subject to section 10, section 34 of the Act of 2000 as read with section 34B or 34C, as appropriate, of that Act, and section 37 of that Act as read with section 37R or 37S, as appropriate, of that Act, the following are, by virtue of this subsection, void:

(a) any restriction, to the extent that it purports to be an operating restriction, imposed, on or after the commencement of this section, by a person other than the competent authority;

(b) any revocation, revocation and replacement, or amendment of the terms, of an operating restriction purporting to be effected, on or after the commencement of this section, by a person other than the competent authority.