Paragraph 34 Quadrantal rule and semi-circular rule
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, shall be flown at a level appropriate to its magnetic track, in accordance with Table 1 or Table 2, as appropriate.
For the purposes of paragraph (1), the level of flight shall be measured by an altimeter set—
in the case of a flight over the Territory, to a pressure setting of 1013.2 hectopascals; or
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.
An aircraft may be flown at a level other than the level required by paragraph (1) if it flies—
in conformity with instructions given by an air traffic control unit;
in accordance with notified en-route holding patterns; or
in accordance with holding procedures notified in relation to an aerodrome.
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 |