1. corrected altitude-Indicated altitude of an aircraft altimeter corrected for the temperature of the column of air below the aircraft, the correction being based on the estimated departure of existing temperature from standard atmospheric temperature; an approximation of true altitude.
2. density altitude-The altitude in the standard atmosphere at which the air has the same density as the air at the point in question. An aircraft will have the same performance characteristics as it would have in a standard atmosphere at this altitude.
3. indicated altitude-The altitude above mean sea level indicated on a pressure altimeter set at current local altimeter setting.
4. pressure altitude-The altitude in the standard atmosphere at which the pressure is the same as at the point in question. Since an altimeter operates solely on pressure, this is the uncorrected altitude indicated by an altimeter set at standard sea level pressure of 29.92 inches or 1013 millibars.
5. radar altitude-The altitude of an aircraft determined by radar-type radio altimeter; thus the actual distance from the nearest terrain or water feature encompassed by the downward directed radar beam. For all practical purposes, it is the" actual" distance above a ground or inland water surface or the true altitude above an ocean surface.
6. true altitude-The exact distance above mean sea level.

The height of a level, point, or object measured in feet Above Ground Level (AGL) or from Mean Sea Level (MSL). (See FLIGHT LEVEL.)

1. MSL Altitude- Altitude expressed in feet measured from mean sea level.
2. AGL Altitude- Altitude expressed in feet measured above ground level.
3. Indicated Altitude- The altitude as shown by an altimeter. On a pressure or barometric altimeter it is altitude as shown uncorrected for instrument error and uncompensated for variation from standard atmospheric conditions. (See ALTITUDE.)

The vertical distance of a level, a point or an object considered as a point, measured from mean sea level (MSL).

• ICAO Definition: The vertical distance of a level, a point, or an object considered as a point, measured from Mean Sea Level (MSL).
• USA Definition: The height of a level, point or object measured in feet Above Ground Level (AGL) or from Mean Sea Level (MSL).
  1. AGL Altitude Altitude expressed in feet measured above ground level (QFE).
  2. MSL Altitude Altitude expressed in feet measured from mean sea level (QNH).
  3. Indicated Altitude The Altitude as shown by an altimeter. On a pressure barometric altimeter it is altitude as shown uncorrected for instrument error and uncompensated for variation from standard atmospheric conditions.