The division of the Canadian Domestic Airspace (CDA) into seven classes, each identified by a single letter: A, B, C, D, E, F or G. The application of any classification to an airspace structure determines the operating rules, the level of ATC service provided within the structure and, in some instances, communications and equipment requirements. The horizontal and vertical limits of airspace are described in the Designated Airspace Handbook (DAH).

(a) Class A airspace

Controlled high-level airspace within which only IFR flight is permitted and ATC separation is provided to all aircraft. The vertical dimensions of Class A high level controlled airspace are as follows:

(i) Southern Control Area (SCA): 18 000 ft ASL to FL 600 inclusive;

(ii) Northern Control Area (NCA): FL 230 to FL 600 inclusive; and

(iii) Arctic Control Area (ACA): FL 270 to FL 600 inclusive.

(b) Class B airspace

Controlled low-level airspace within which both IFR and VFR flights are permitted and ATC separation is provided to all aircraft. Class B low level controlled airspace is all airspace above 12 500 ft ASL, or at and above the minimum en route altitude (MEA), whichever is higher, up to, but not including,18 000 ft ASL. Terminal control areas (TCA) and associated primary control zones may also be classified as Class B airspace.

(c) Class C airspace

Controlled airspace within which both IFR and VFR flights are permitted, but VFR flights require a clearance to enter. ATC separation is provided to all IFR aircraft and, as necessary to resolve possible conflicts, between IFR and VFR aircraft. TCAs and associated primary control zones may be classified as Class C airspace.

(d) Class D airspace

Controlled airspace within which both IFR and VFR flights are permitted, but VFR flights must establish two-way communications with the appropriate ATC agency prior to entering the airspace. ATC separation is provided only to IFR aircraft. TCAs and associated primary control zones may be classified as Class D airspace.

(e) Class E airspace

Controlled airspace within which both IFR and VFR flights are permitted, but VFR flights do not have to establish two-way communications with the appropriate ATC agency prior to entering the airspace. ATC separation is provided only to IFR aircraft. All high level controlled airspace above FL 600 within the SCA, NCA and ACA is Class E airspace. Also, low level airways, low level fixed area navigation (RNAV) routes, control area extensions, transition areas, or control zones established without an operating control tower may be classified as Class E airspace.

(f) Class F airspace

Special-use airspace that may be a restricted area, an advisory area, military operations areas or danger areas and can be controlled airspace, uncontrolled airspace or a combination of both. It is described in terms of horizontal and vertical dimensions, effective for a specified period of time. Although both IFR and VFR flights are permitted in Class F airspace, restricted-airspace access is not authorized without the approval of the user/controlling agency, and advisory-area access is normally reserved for participating aircraft. Non-participating flights should avoid flight within advisory areas, and ATC will not clear non-participating IFR aircraft into an active advisory area. Rules for special-use airspace are as specified in the DAH, and, if not specified, or when the area is not active, the appropriate rules for the surrounding airspace apply.

(g) Class G airspace

Airspace within which IFR and VFR flights are not subject to control. Airspace shall be classified as Class G if it has not been designated as A, B, C, D, E or F.

Note: A poster entitled "Canada's Airspace" (TP 6010) provides a graphic presentation of airspace structure.