JO 7110.65 4-5-5

When the prescribed minimum altitude for IFR operations is at or above 18,000 feet MSL and the atmospheric pressure is less than 29.92”, add the appropriate adjustment factor from TBL 4-5-3 to the flight level equivalent of the minimum altitude in feet to determine the adjusted minimum flight level.

TBL 4-5-3 Minimum FL Adjustment Altimeter Setting

Adjustment Factor

29.92” or higher

None

29.91” to 29.42”

500 feet

29.41” to 28.92”

1,000 feet

28.91” to 28.42”

1,500 feet

28.41” to 27.92”

2,000 feet