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

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.

Source FAA Pilot/Controller Glossary · checked 2026-08-25