airspace Class A

airspace Class A

Airspace classification letter is displayed in association with the airspace type and vertical limits on aeronautical charts in this manner.An airspace in which only IFR (instrument flight rules) flights are permitted. All flights are subject to air traffic control service and are separated from each other. This is normally allocated to busier airports only. In the United States, generally, that airspace from 18,000 ft MSL (mean sea level) up to and including FL (flight level) 600, including airspace overlying waters within 12 NM of the coast of the 48 contiguous states and Alaska and designated international airspace beyond 12 NM of the coast of the 48 contiguous states and Alaska within areas of domestic radio navigational signals or ATC (air traffic control) coverage, and within which domestic procedures are applied. Class A airspace is not specifically charted in the United States, but it is in some countries. Formerly known as PCA, or positive control area.