25.—(1) Within Class B airspace:
(a)an aircraft flying within Class B airspace at or above flight level 100 shall remain clear of cloud and in a flight visibility of at least 8 km;
(b)an aircraft flying within Class B airspace below flight level 100 shall remain clear of cloud and in a flight visibility of at least 5 km.
(2) Within Class C, Class D or Class E airspace:
(a)an aircraft flying within Class C, Class D or Class E airspace at or above flight level 100 shall remain at least 1500 metres horizontally and 1000 feet vertically away from cloud and in a flight visibility of at least 8 km;
(b)subject to sub-paragraph (c), an aircraft flying within Class C, Class D or Class E airspace below flight level 100 shall remain at least 1500 metres horizontally and 1000 feet vertically away from cloud and in a flight visibility of at least 5 km;
(c)sub-paragraph (b) shall be deemed to be complied with if:
(i)the aircraft is not a helicopter and is flying at or below 3000 feet above mean sea level at a speed which, according to its airspeed indicator, is 140 knots or less and it remains clear of cloud, in sight of the surface and in a flight visibility of at least 5 km; or
(ii)the aircraft is a helicopter flying at or below 3000 feet above mean sea level and it remains clear of cloud and in sight of the surface.