- minimum IFR altitude
- The lowest IFR (instrument flight rules) altitude established for use in a specific airspace. Depending on the airspace concerned, the minimum IFR altitude may be a minimum obstacle clearance altitude (MOCA), a minimum en route altitude (MEA), a minimum sector altitude (MSA), a minimum vectoring altitude (MVA), a geographic area safe altitude (GASA), a safe altitude 100 NM, a transition altitude, or a missed approach altitude. The minimum IFR altitude provides obstacle clearance but may or may not be within controlled airspace. Minimum altitudes are published on aeronautical charts. When minimum altitudes are not specified, the following rules apply:i. In a designated mountainous area, 2000 ft above the highest obstacle within a horizontal distance of 5 statute miles from the course to be flown.ii. In other than mountainous areas, 1000 ft above the highest obstacle within 5 statute miles from the course to be flown.iii. In other cases, as authorized by ATC (air traffic control) or by the operator.
Aviation dictionary. 2014.