Controlled airspace is an area of Airspace in which air traffic control (ATC) services are provided to aircraft operating within it. The primary purpose of controlled airspace is to ensure the safe and efficient separation of aircraft, thereby reducing the risk of collisions.
Controlled airspace is designated by the aviation authority of each country and is typically classified according to the level of service provided by ATC. In the United States, for example, there are six classes of controlled airspace:
Class A Airspace: extends from 18,000 feet above mean sea level (MSL) up to flight level (FL) 600 and is typically used by commercial airliners operating on instrument flight rules (IFR) flights.
Class B Airspace: surrounds the busiest airports and provides highly controlled airspace to accommodate the high volume of air traffic in these areas.
Class C Airspace: is typically found around medium-sized airports and provides a lower level of control than Class B Airspace.
Class D Airspace: surrounds smaller airports and provides basic ATC services to aircraft operating within it.
Class E Airspace: extends from the surface up to various altitudes and is used to provide ATC services in areas where there is not enough air traffic to justify the use of other classes of controlled airspace.
Class G Airspace: is uncontrolled airspace that is not designated as any of the other classes of controlled airspace.
In general, aircraft operating in controlled airspace are required to have a functioning radio and to follow ATC instructions in order to ensure the safe and efficient flow of air traffic.
Status:: #wiki/notes/mature
Plantations:: Aeronautics Regulation
References:: Le Manuel de Pilotage d'Avion