minimum holding altitude

minimum holding altitude (MHA)

Minimum holding level as determined by the obstacle clearance surface related to the holding area and the buffer area.

The lowest altitude prescribed for a holding pattern, which complies with requirements for obstruction clearance and ensures good reception of radio signals and of navigational aids. The minimum holding level provides a clearance of at least 1000 ft (300 m) above obstacles in the holding area, a value (as given in the table) above obstacles in the buffer area. The minimum holding altitude to be published shall be rounded up to the nearest 100 ft, or 50 m, as appropriate. If no MHA is prescribed, then the following minimum IFR (instrument flight rules) altitudes 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.

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