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Pilot/Controller Glossary

3/29/18

PCG C−7

airport contains at least one primary airport around

which the airspace is designated (for specific

designations and descriptions of the airspace classes,

please refer to 14 CFR Part 71).

c. Controlled airspace in the United States is

designated as follows:

1. CLASS A− Generally, that airspace from

18,000 feet MSL up to and including FL 600,

including the airspace overlying the waters within 12

nautical miles of the coast of the 48 contiguous States

and Alaska. Unless otherwise authorized, all persons

must operate their aircraft under IFR.

2. CLASS B− Generally, that airspace from the

surface to 10,000 feet MSL surrounding the nation’s

busiest airports in terms of airport operations or

passenger enplanements. The configuration of each

Class B airspace area is individually tailored and

consists of a surface area and two or more layers

(some Class B airspace areas resemble upside-down

wedding cakes), and is designed to contain all

published instrument procedures once an aircraft

enters the airspace. An 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. The cloud clearance requirement for VFR

operations is “clear of clouds.”

3. CLASS C− Generally, that airspace from the

surface to 4,000 feet above the airport elevation

(charted in MSL) surrounding those airports that

have an operational control tower, are serviced by a

radar approach control, and that have a certain

number of IFR operations or passenger enplane-

ments. Although the configuration of each Class C

area is individually tailored, the airspace usually

consists of a surface area with a 5 nautical mile (NM)

radius, a circle with a 10NM radius that extends no

lower than 1,200 feet up to 4,000 feet above the

airport elevation, and an outer area that is not charted.

Each person must establish two-way radio commu-

nications with the ATC facility providing air traffic

services prior to entering the airspace and thereafter

maintain those communications while within the

airspace. VFR aircraft are only separated from IFR

aircraft within the airspace.

(See OUTER AREA.)

4. CLASS D− Generally, that airspace from the

surface to 2,500 feet above the airport elevation

(charted in MSL) surrounding those airports that

have an operational control tower. The configuration

of each Class D airspace area is individually tailored

and when instrument procedures are published, the

airspace will normally be designed to contain the

procedures. Arrival extensions for instrument

approach procedures may be Class D or Class E

airspace. Unless otherwise authorized, each person

must establish two-way radio communications with

the ATC facility providing air traffic services prior to

entering the airspace and thereafter maintain those

communications while in the airspace. No separation

services are provided to VFR aircraft.

5. CLASS E− Generally, if the airspace is not

Class A, Class B, Class C, or Class D, and it is

controlled airspace, it is Class E airspace. Class E

airspace extends upward from either the surface or a

designated altitude to the overlying or adjacent

controlled airspace. When designated as a surface

area, the airspace will be configured to contain all

instrument procedures. Also in this class are Federal

airways, airspace beginning at either 700 or 1,200

feet AGL used to transition to/from the terminal or en

route environment, en route domestic, and offshore

airspace areas designated below 18,000 feet MSL.

Unless designated at a lower altitude, Class E

airspace begins at 14,500 MSL over the United

States, including that airspace overlying the waters

within 12 nautical miles of the coast of the 48

contiguous States and Alaska, up to, but not

including 18,000 feet MSL, and the airspace above

FL 600.

CONTROLLED AIRSPACE [ICAO]− An airspace

of defined dimensions within which air traffic control

service is provided to IFR flights and to VFR flights

in accordance with the airspace classification.

Note: Controlled airspace is a generic term which

covers ATS airspace Classes A, B, C, D, and E.

CONTROLLED TIME OF ARRIVAL− Arrival time

assigned during a Traffic Management Program. This

time may be modified due to adjustments or user

options.

CONTROLLER−

(See AIR TRAFFIC CONTROL SPECIALIST.)

CONTROLLER [ICAO]− A person authorized to

provide air traffic control services.

CONTROLLER PILOT DATA LINK

COMMUNICATIONS (CPDLC)− A two−way

digital communications system that conveys textual

air traffic control messages between controllers and

9/13/18

Pilot/Controller Glossary