Above this, Class C airspace is used, although generally only in a sector, and not 360° around the airport. Class E is used along the populated coastal areas, from 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. Transition from GAAP to Class D Australia used to have a non-standard class of airspace for use at the capital city general aviation airports, called a General Aviation Airport Procedures Zone (GAAP Zone). A control tower provided procedural clearances for all aircraft inside the zone. Additionally, any aircraft operating within of the zone must obtain a clearance. VFR aircraft arrive and depart using standard arrival and departure routes, while instrument arrival and departure procedures are published for IFR operations. During visual meteorological conditions (VMC), IFR aircraft are not provided with full IFR services. During instrument meteorological conditions (IMC), or marginal VMC, VFR operations are restricted in order to facilitate full IFR service for IFR aircraft. In June 2010, all GAAP aerodromes were changed to Class D aerodromes, and the previous Class D procedures were changed. The new Class D procedures are similar to the FAA Class D procedures. VFR aircraft are no longer required to enter the airspace via set inbound/outbound points, however can be directed there by ATC. VFR and IFR aircraft now require taxi clearance in the "manoeuvring area" of the aerodrome, but can still taxi within set apron areas without a clearance. IFR aircraft now receive slot times and the visibility requirements of Special VFR are reduced from 3000m visibility to 1600m. Canada There are seven airspace classes in use in Canada (letters A through G), but the letters do not always correspond with ICAO definitions. Denmark Class A is generally used above FL195. Class B is not used. Class C is used for busy terminal areas, namely Billund TMA and København TMA. All airspace above FL195 is also class C. Class D is used for all control zones and most terminal areas. Class E is generally used for all airspace from 3500 feet to FL195, with the exception of TMA's and airspace over the North Sea. Class F is not used. Class G is used below 3500 feet, except around controlled airports, and below