85.—(1) Subject to paragraph (3), an aircraft registered elsewhere than in the United Kingdom must not fly in Required Navigation Performance airspace in the United Kingdom unless it complies with paragraph (2).
(2) An aircraft complies with this paragraph if it is registered elsewhere than in the United Kingdom and—
(a)it is equipped with area navigation equipment so as to comply with the law of the country in which the aircraft is registered in so far as that law requires it to be so equipped when flying within designated required navigation performance airspace; and
(b)the navigation equipment is capable of being operated so as to enable the aircraft to maintain the navigation performance capability notified for the airspace in which the aircraft is flying, and is so operated.
(3) Paragraph (2) does not apply to an aircraft if—
(a)the appropriate United Kingdom air traffic control unit, having been made aware of the lack of compliance, authorises the flight; and
(b)the aircraft complies with any instructions the air traffic control unit may give.