12.—(1) Subject to paragraph (2), a flying machine, glider or airship flying in the vicinity of what the commander of the aircraft knows, or ought reasonably to know, to be an aerodrome shall—
(a)conform to the pattern of traffic formed by other aircraft intending to land at that aerodrome or keep clear of the airspace in which the pattern is formed; and
(b)make all turns to the left unless ground signals otherwise indicate.
(2) Paragraph (1) shall not apply if the air traffic control unit at that aerodrome otherwise authorises.