REVIEW OF ALTITUDE DEFINITIONS
(IA) is the altitude reading on the aircraft altimeter when it is set to the
local area (nearest station) barometric pressure (altimeter setting).
Calibrated altitude: (CA) is indicated altitude corrected for instrument and installation
(PA) is the calibrated altitude corrected for the difference between
local atmospheric pressure and the standard datum plane, 29.92.
Pressure altitude is the reference used to calculate True Airspeed.
(TA) is the actual height of the aircraft above Mean Sea Level (MSL).
Found by correcting CA for density. TA is very important because
terrain elevation on navigational charts is labeled in feet MSL.
Actual height of the aircraft above the surface of the earth. Also known
as altitude Above Ground Level (AGL).
Figure 4.4-3 shows a comparison of these altitudes.
Figure 4.4-3 Altitudes