Airspace Classes

Class	ATC Services Provided
Class A	Separation between aircraft that comply with the instrument flight rules VFR not allowed Established above FL180 within radar environments and above FL245 in non-radar environments, including Oceanic airspace.
Class C	Separation between planes that comply with the instrument flight rules and all other planes. Separation between planes that comply with the visual flight rules and all planes that comply with the instrument flight rules, and traffic information on other planes. Class C airspace is established over designated major airports. These airports include Melbourne, Adelaide, Perth, Darwin, Cairns, Townsville, Brisbane, Gold Coast, Sydney, Canberra and Williamtown. The airspace extends from FL180, down in "steps" (like a "wedding cake" tipped upside down) to ground level.
Class D	Separation between aircraft that comply with the instrument flight rules and other planes that comply with the instrument flight rules. Traffic information for other aircraft. Class D extends below Class C in steps from 4,500 FT to ground level over some airfields that do not have a local radar display. These airfields include: Hobart, Launceston, Albury, Tamworth, Coffs Harbour, Maroochydore, Rockhampton, Mackay, Hamilton Island, Alice Springs and all former General Aviation Aerodrome Procedures (GAAP) airports.
Class E	Separation between planes that comply with the instrument flight rules and other planes that comply with the instrument flight rules. A traffic information service to all other planes on request, as far as is practical. Typically established above 8,500 FT in corridors within radar environments and above FL180 in non-radar environments.
Class G	In Class G airspace a traffic information service is provided to all aircraft that comply with the instrument flight rules about other aircraft that comply with the instrument flight rules. Class G is established wherever Class A, C, D or E is not established.