The Air Navigation (Overseas Territories) Order 2013

Quadrantal rule and semi-circular rule

34.—(1) Subject to paragraphs (2) and (3), an aircraft in level flight above 3,000 feet above mean sea level or above the appropriate transition altitude, whichever is the higher, must be flown at a level appropriate to its magnetic track, in accordance with Table 1 or Table 2, as appropriate.

(2) For the purposes of paragraph (1), the level of flight must be measured by an altimeter set—

(a) in the case of a flight over the Territory, to a pressure setting of 1013.2 hectopascals; or

(b) in the case of any other flight, according to the system published by the competent authority in relation to the area over which the aircraft is flying.

(3) An aircraft may be flown at a level other than the level required by paragraph (1) if it flies—

(a) in conformity with instructions given by an air traffic control unit;

(b) in accordance with notified en-route holding patterns; or

(c) in accordance with holding procedures notified in relation to an aerodrome.

(4) For the purposes of this rule “transition altitude” means the altitude which is notified in relation to flights over notified areas.

Table 1

Flights at Levels below 19,500 Feet

Magnetic Track	Cruising Level
Less than 90°	Odd thousands of feet
90° but less than 180°	Odd thousands of feet + 500 feet
180° but less than 270°	Even thousands of feet
270° but less than 360°	Even thousands of feet + 500 feet

Table 2

Flights at Levels above 19,500 Feet

Magnetic Track	Cruising Level
Less than 180°	21,000 feet
	23,000 feet
	25,000 feet
	27,000 feet
	29,000 feet
	31,000 feet
	33,000 feet
	35,000 feet
	37,000 feet
	39,000 feet
	41,000 feet or higher levels at intervals of 4,000 feet
180° but less than 360°	20,000 feet
	22,000 feet
	24,000 feet
	26,000 feet
	28,000 feet
	30,000 feet
	32,000 feet
	34,000 feet
	36,000 feet
	38,000 feet
	40,000 feet
	43,000 feet or higher levels at intervals of 4,000 feet