TBL 7-2-3

ICAO Cold Temperature Error Table

Reported Temp _C

Height Above Airport in Feet

+10

-10

-20

-30

-40

-50

EXAMPLE-
Temperature-10 degrees Celsius, and the aircraft altitude is 1,000 feet above the airport elevation. The chart shows that
the reported current altimeter setting may place the aircraft as much as 100 feet below the altitude indicated by the altimeter.

7-2-4. High Barometric Pressure
a. Cold, dry air masses may produce barometric
pressures in excess of 31.00 inches of Mercury, and
many altimeters do not have an accurate means of
being adjusted for settings of these levels. When the
altimeter cannot be set to the higher pressure setting,
the aircraft actual altitude will be higher than the
altimeter indicates.
REFERENCE-
AIM, Paragraph 7-2-3 , Altimeter Errors.

b. When the barometric pressure exceeds
31.00 inches, air traffic controllers will issue the
actual altimeter setting, and:
1. En Route/Arrivals. Advise pilots to remain
set on 31.00 inches until reaching the final approach
segment.

7-2-4

2. Departures. Advise pilots to set 31.00 inches prior to reaching any mandatory/crossing altitude
or 1,500 feet, whichever is lower.
c. The altimeter error caused by the high pressure
will be in the opposite direction to the error caused by
the cold temperature.
7-2-5. Low Barometric Pressure
When abnormally low barometric pressure conditions occur (below 28.00), flight operations by
aircraft unable to set the actual altimeter setting are
not recommended.
NOTE-
The true altitude of the aircraft is lower than the indicated
altitude if the pilot is unable to set the actual altimeter
setting.

Altimeter Setting Procedures