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Pilot/Controller Glossary

3/29/18

PCG A−9

AIRPORT TRAFFIC CONTROL SERVICE−  A

service provided by a control tower for aircraft

operating on the movement area and in the vicinity of

an airport.

(See MOVEMENT AREA.)
(See TOWER.)
(See ICAO term AERODROME CONTROL

SERVICE.)

AIRPORT TRAFFIC CONTROL TOWER−

(See TOWER.)

AIRSPACE CONFLICT− Predicted conflict of an

aircraft and active Special Activity Airspace (SAA).

AIRSPACE FLOW PROGRAM (AFP)− AFP is a

Traffic Management (TM) process administered by

the Air Traffic Control System Command Center

(ATCSCC) where aircraft are assigned an Expect

Departure Clearance Time (EDCT) in order to

manage capacity and demand for a specific area of the

National Airspace System (NAS). The purpose of the

program is to mitigate the effects of en route

constraints. It is a flexible program and may be

implemented in various forms depending upon the

needs of the air traffic system.

AIRSPACE HIERARCHY− Within the airspace

classes, there is a hierarchy and, in the event of an

overlap of airspace: Class A preempts Class B, Class

B preempts Class C, Class C preempts Class D, Class

D preempts Class E, and Class E preempts Class G.

AIRSPEED− The speed of an aircraft relative to its

surrounding air mass. The unqualified term

“airspeed” means one of the following:

a. Indicated Airspeed− The speed shown on the

aircraft airspeed indicator. This is the speed used in

pilot/controller communications under the general

term “airspeed.”

(Refer to 14 CFR Part 1.)

b. True Airspeed− The airspeed of an aircraft

relative to undisturbed air. Used primarily in flight

planning and en route portion of flight. When used in

pilot/controller communications, it is referred to as

“true airspeed” and not shortened to “airspeed.”

AIRSTART− The starting of an aircraft engine while

the aircraft is airborne, preceded by engine shutdown

during training flights or by actual engine failure.

AIRWAY− A Class E airspace area established in the

form of a corridor, the centerline of which is defined

by radio navigational aids.

(See FEDERAL AIRWAYS.)
(See ICAO term AIRWAY.)
(Refer to 14 CFR Part 71.)
(Refer to AIM.)

AIRWAY [ICAO]− A control area or portion thereof

established in the form of corridor equipped with

radio navigational aids.
AIRWAY BEACON− Used to mark airway segments

in remote mountain areas. The light flashes Morse

Code to identify the beacon site.

(Refer to AIM.)

AIT−

(See AUTOMATED INFORMATION

TRANSFER.)

ALERFA (Alert Phase) [ICAO]− A situation wherein

apprehension exists as to the safety of an aircraft and

its occupants.
ALERT− A notification to a position that there

is an aircraft-to-aircraft or aircraft-to-airspace

conflict, as detected by Automated Problem

Detection (APD).
ALERT AREA−

(See SPECIAL USE AIRSPACE.)

ALERT NOTICE (ALNOT)− A request originated

by a flight service station (FSS) or an air route traffic

control center (ARTCC) for an extensive commu-

nication search for overdue, unreported, or missing

aircraft.
ALERTING SERVICE− A service provided to notify

appropriate organizations regarding aircraft in need

of search and rescue aid and assist such organizations

as required.
ALNOT−

(See ALERT NOTICE.)

ALONG−TRACK DISTANCE (ATD)− The hori-

zontal distance between the aircraft’s current position

and a fix measured by an area navigation system that

is not subject to slant range errors.
ALPHANUMERIC DISPLAY− Letters and numer-

als used to show identification, altitude, beacon code,

and other information concerning a target on a radar

display.

(See AUTOMATED RADAR TERMINAL

SYSTEMS.)