BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

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AFMAN 11-217V1 3 JANUARY 2005
Figure 8.2. Example 2 - Off-scale Altimeter Settings.
8.1.3.1. Subtracting Corrections. In example one (Figure 8.1), you have been cleared
to fly the HI-TACAN RWY 22 at Gander INTL. The local altimeter setting is 31.20
inches. Your altimeter's maximum range is 31.00 inches. First, determine the
difference between the actual ALSTG (31.20) and the value set in your altimeter
(31.00). Take this result (.20) and multiply by 1,000. This will give you your
correction factor (200 ft). Because the altimeter setting exceeds the altimeter's
maximum range, the correction (200 ft) will be subtracted from all approach altitudes.
These corrections are indicated on the approach.
8.1.3.2. Adding Corrections. In example two (Figure 8.2), you have been cleared to
fly the TACAN RWY 10 at Shemya AFB. The local altimeter setting is 27.90 inches.
Your altimeter's minimum range is 28.10 inches. First, determine the difference
between the actual ALSTG (27.90) and the value set in your altimeter (28.10). Take
this result (.20) and multiply by 1,000. This will give you your correction factor (200
ft). Because the altimeter setting is less than the altimeter's minimum range, the
correction (200 ft) will be added to all approach altitudes. These corrections are
indicated on the approach.
8.1.3.2.1. NOTE: Because high pressure is usually associated with fair weather
(VMC), the use of correction factors where the actual altimeter setting exceeds
the altimeter upper limit does not present a serious problem. On the other hand,
low ceilings and visibilities are often associated with extremely low pressure (low
altimeter settings). Aircraft that must execute an actual instrument approach
(IMC) under these conditions should consider this situation an emergency. It is
further recommended that all available approach and navigation aids (radar
altimeters, Ground Controlled Approach (GCA) monitored approach, etc.) be
used to determine aircraft position and altitude.
8.1.4. Cold Weather Altimeter Corrections. Pressure altimeters are calibrated to indicate
true altitude under International Standard Atmospheric (ISA) conditions. Any deviation
from these standard conditions will result in an erroneous reading on the altimeter. This