***Link*** :: [§ 91.179 IFR cruising altitude or flight level.](https://www.ecfr.gov/current/title-14/section-91.179) ***Description*** :: `= this.link` ***Author*** :: [[FAA]] #### Key Quotes * **In controlled airspace**... maintain the altitude or flight level assigned * **In uncontrolled airspace**... * * 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 * 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). * When operating at flight level 290 and above in non-RVSM airspace... * When operating at flight level 290 and above in airspace designated as Reduced Vertical Separation Minimum (RVSM) airspace... #source #far