121.—(1) An aircraft registered in the United Kingdom must not fly in North Atlantic Minimum Navigation Performance Specification airspace unless it is equipped with navigation systems which enable the aircraft to maintain the prescribed navigation performance capability.
(2) The equipment required by paragraph (1) must—
(a)be approved by EASA or the CAA;
(b)be installed in a manner approved by EASA in the case of an EASA aircraft and by the CAA in the case of a non-EASA aircraft;
(c)be maintained in a manner approved by the CAA; and
(d)while the aircraft is flying in that airspace, be operated in accordance with procedures approved by the CAA.
122.—(1) Unless otherwise authorised by the appropriate air traffic control unit, an aircraft registered in the United Kingdom must not fly in Reduced Vertical Separation Minimum airspace unless it is equipped with height keeping systems which enable the aircraft to maintain the required height keeping performance capability.
(2) The equipment required by paragraph (1) must—
(a)be approved by EASA or the CAA;
(b)be installed in a manner approved by EASA in the case of an EASA aircraft and by the CAA in the case of a non-EASA aircraft;
(c)be maintained in a manner approved by the CAA; and
(d)while the aircraft is flying in that airspace, be operated in accordance with procedures approved by the CAA.
123.—(1) Unless otherwise authorised by the appropriate air traffic control unit an aircraft registered elsewhere than in the United Kingdom must not fly in Reduced Vertical Separation Minimum airspace in the United Kingdom unless—
(a)it is so equipped with height keeping systems 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 in any specified airspace; and
(b)the equipment is capable of being operated so as to enable the aircraft to maintain the height keeping performance prescribed for the airspace in which the aircraft is flying, and it is so operated.
124.—(1) Subject to paragraph (3) an aircraft registered in the United Kingdom must not fly in Required Navigation Performance airspace unless it is equipped with area navigation equipment which enables the aircraft to maintain the navigation performance capability notified, prescribed or otherwise designated for that airspace.
(2) The equipment required by paragraph (1) must—
(a)be approved by EASA or the CAA;
(b)be installed in a manner approved by EASA in the case of an EASA aircraft and the CAA in the case of a non-EASA aircraft;
(c)be maintained in a manner approved by the CAA; and
(d)while the aircraft is flying in that airspace, be operated in accordance with procedures approved by the CAA.
(3) An aircraft need not comply with the requirements of this article if—
(a)the appropriate 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.
125.—(1) An aircraft registered elsewhere than in the United Kingdom must not fly in Required Navigation Performance airspace in the United Kingdom unless 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.
(2) Subject to paragraph (3), the navigation equipment must be 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 must be so operated.
(3) An aircraft need not comply with the requirements of this article 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.