The Rules of the Air Regulations 2007

Flight within controlled airspace

27.—(1) Subject to paragraph (4), an aircraft flying within Class B airspace—

(a) at or above flight level 100 shall remain clear of cloud and in a flight visibility of at least 8 km; and

(b) below flight level 100 shall remain clear of cloud and in a flight visibility of at least 5 km.

(2) Subject to paragraphs (3) and (4), an aircraft flying within Class C, Class D or Class E airspace—

(a) at or above flight level 100 shall remain at least 1,500 metres horizontally and 1,000 feet vertically away from cloud and in a flight visibility of at least 8 km;

(b) below flight level 100 shall remain at least 1,500 metres horizontally and 1,000 feet vertically away from cloud and in a flight visibility of at least 5 km.

(3) An aircraft shall be deemed to have complied with paragraph (2)(b) if—

(a) the aircraft is not a helicopter and it—

(i) flies at or below 3,000 feet above mean sea level;

(ii) flies at a speed which, according to its airspeed indicator, is 140 knots or less; and

(iii) remains clear of cloud, with the surface in sight and in a flight visibility of at least 5 km; or

(b) the aircraft is a helicopter and it—

(i) flies at or below 3,000 feet above mean sea level; and

(ii) remains clear of cloud, with the surface in sight and in a flight visibility of at least 1,500 metres.

(4) Paragraphs (1) and (2) shall not apply to a helicopter that is air-taxiing or conducting manoeuvres in accordance with rule 6(i).