Class E is used along the populated coastal areas, from 8,500 feet (2,590 m) to the base of the overlying Class A or Class C airspace. Class F is not used. Class G is used wherever other classes are not—almost always from the surface to the base of the overlying Class A, C, D or E airspace.
Within these blue lines, the floor and the ceiling of the Class B airspace is defined. The lateral boundaries of Class B airspace are individually tailored to facilitate arriving and departing traffic operating under IFR. Class B airspace extends from the surface to generally 10,000 feet (3,000 m) MSL.
Class G airspace is defined wherever Class A and Class C airspaces are not defined. Class G airspace allows IFR and VFR operations. For altitudes less than 3,000 metres (9,800 ft) the speed must not exceed 450 kilometres per hour (280 mph; 240 kn).
Class C is used for controlled airspace. Class D is used for controlled airspace where C is not used. Class G is used elsewhere. G* is used in TIZ and TIA where two-way radio communication is required during opening hours. Russia. Russia adopted a modified version of ICAO airspace classification on November 1, 2010.
Class E is the most common type of airspace in the United States, but it's often the least understood. Class E Is Controlled - But How? One big confusion point for students is that Class E airspace IS controlled airspace. But why is it controlled? In Class E, IFR aircraft are controlled by ATC.