7–2–1 General

a. Aircraft altimeters are subject to the following errors and weather factors:

1. Instrument error.

2. Position error from aircraft static pressure systems.

3. Nonstandard atmospheric pressure.

4. Nonstandard temperatures.

b. The standard altimeter 29.92 inches Mercury ("Hg.) setting at the higher altitudes eliminates station barometer errors, some altimeter instrument errors, and errors caused by altimeter settings derived from different geographical sources.