Mean Sea Level
From FlightGear wiki
(Redirected from AMSL)
Mean sea level (MSL) is a measure of the average height of the ocean's surface (such as the halfway point between the mean high tide and the mean low tide) and plays an extremely important role in aviation, where standard sea level pressure is used as the measurement reference of altitude at flight levels.
Above Mean Sea Level
The altitude measured in reference with the Mean Sea Level (opposite (AGL)).
