Airspace

• Author: Timothy M. Ravich
• Profession: Lawyer
• Pages: 59-89

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C 4

Airspace

The term airspace is not defined in the Federal Aviation Regulations (FARs). Rather,

regulators speak in terms of regulatory and nonregulatory airspace with respect

to the National Airspace System (NAS). Controlled airspace is “an airspace of a defined

dimension within which air traffic control service is provided to . . . flights in accordance

with the airspace classification.”1 Controlled airspace consists of several “classes” of air-

space, as follows:2

t Class A Airspace. Class A airspace is generally the airspace from 18,000 feet mean

sea level (MSL) up to and including flight level (FL) 60,000 feet, including the

airspace overlying the waters within 12 nautical miles (NM) of the coast of the

48 contiguous states and Alaska. Unless otherwise authorized, all operation in

Class A airspace is conducted under instrument flight rules (IFR).

t Class B Airspace. Class B airspace is generally airspace from the surface to

10,000 feet MSL surrounding the nation’s busiest airports in terms of airport

operations or passenger enplanements. e config uration of each Cla ss B airspace

area is individually tailored, consists of a surface area and two or more layers

(some Class B airspace areas resemble upside- down wedding cake s), and is designed

to contain all published instru ment procedures once an aircraf t enters the airspace.

An air traffic control (ATC) clearance is required for all aircraft to operate in

the area, and all aircraft that are so cleared receive separation services within the

airspace.

t Class C Airspace. Class C airspace is generally airspace from the surface to

4,000 feet above the airport elevation (charted in MSL) surrounding those air-

ports that have an operational control tower, are serviced by a radar approach

control, and have a certain number of IFR operations or pas senger enplanements.

1 F. A A ., P’ H   A  K , C  : A , 14-2.

2 Id.

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Although the configuration of each Class C area is individually tailored, the

airspace usually consists of a surface area with a 5-NM radius, an outer circle

with a 10-NM radius that extends from 1,200 feet to 4,000 feet above the air-

port elevation, and an outer area. Each aircraft must establish two- way radio

communications with the ATC facility providing air tra ffic services prior to enter-

ing the airspace and thereafter maintain those communications while within the

airspace.

t Class D Airspace. Class D airspace is generally airspace from the surface to

2,500 feet above the airport elevation (charted i n MSL) surrounding those air ports

that have an operational control tower. e configuration of each Class D air-

space area is individually tailored, and when instrument procedures are published,

the airspace is normally designed to contain the procedures. Arrival extensions for

instrument approach procedures (IAPs) may be Class D or Class E air space. Unless

otherwise authorized, each aircraft must establish two- way radio communications

with the ATC facility providing air tra ffic services prior to entering the airspace and

thereafter maintain those communications while in the airspace.

t Class E Airspace. If the airspace is not Class A, B, C, or D and is controlled

airspace, then it is Class E airspace. Class E airspace extends upward from either

the surface or a designated altitude to the overlying or adjacent controlled air-

space. When designated as a su rface area, the airspace is configu red to contain a ll

instrument procedures. Also in this class are federal airways, airspace beginning

at either 700 or 1,200 feet above ground level (AGL) used to transition to and

from the terminal or en route environment, and en route domestic and offshore

airspace areas designated below 18,000 feet MSL. Unless designated at a lower

altitude, Class E airspace be gins at 14,500 MSL over the United States, including

that airspace overlying t he waters within 12 NM of the coast of the 48 contiguous

states and Alaska, up to but not including 18,000 feet MSL, and the airspace

above FL 60,000.

Uncontrolled airspace is known by that term or as Class G airspace. It is the portion of

the airspace that has not been designated as Class A, B, C , D, or E, and extends from the

surface to the base of the overlying Class E airspace.3 Although ATC has no authority or

responsibility to control air tra ffic, pilots learn that there are visual fli ght rules (VFR) that

apply in this airspace.4

Apart from controlled and uncontrolled airspace, the FAA further recognizes six types

of “special use airspace.” Special use airspace or special a rea of operation (SAO) is the des-

ignation for airspace in which certa in activities must be confined or where limitations may

be imposed on aircraft operations that a re not part of those activities.5 Special use a irspace

3 Id. at 14-3.

4 Id.

5 Id.