IFR cruising altitude or flight level.

CFR · 2024-01-01 · US · Title 14

Unless otherwise authorized by ATC, the following rules apply— (a) (b) (1) When operating below 18,000 feet MSL and— (i) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude (such as 3,000, 5,000, or 7,000); or (ii) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude (such as 2,000, 4,000, or 6,000). (2) When operating at or above 18,000 feet MSL but below flight level 290, and— (i) On a magnetic course of zero degrees through 179 degrees, any odd flight level (such as 190, 210, or 230); or (ii) On a magnetic course of 180 degrees through 359 degrees, any even flight level (such as 180, 200, or 220). (3) When operating at flight level 290 and above in non-RVSM airspace, and— (i) On a magnetic course of zero degrees through 179 degrees, any flight level, at 4,000-foot intervals, beginning at and including flight level 290 (such as flight level 290, 330, or 370); or (ii) On a magnetic course of 180 degrees through 359 degrees, any flight level, at 4,000-foot intervals, beginning at and including flight level 310 (such as flight level 310, 350, or 390). (4) When operating at flight level 290 and above in airspace designated as Reduced Vertical Separation Minimum (RVSM) airspace and— (i) On a magnetic course of zero degrees through 179 degrees, any odd flight level, at 2,000-foot intervals beginning at and including flight level 290 (such as flight level 290, 310, 330, 350, 370, 390, 410); or (ii) On

official document · source cfr-2024 · id 14:§ 91.179