AAL (Above Aerodome Level) in aviation, denotes that an altitude is given above the nearest aerodrome or airport. This is usually identical to the altitude above ground level, but AAL is used to be precise.
It’s the elevation of the highest point of the landing area (ICAO). Aerodrome elevation is measured to an accuracy of 1 ft (or 1/2 m). The aerodrome elevation is prominently displayed at the air traffic control tower. Also called above airfield elevation and airport elevation. It is predominantly used in Europe, also called AAE (Above Aerodrome Elevation) or airport elevation.
1. “Aerodrome Elevation” in the Aviation Dictionary on Enacademic.