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12/2/21 

Pilot/Controller Glossary 

differentiated from civil beacons by dualpeaked (two 
quick) white flashes between the green flashes. 

(See INSTRUMENT FLIGHT RULES.) 
(See SPECIAL VFR OPERATIONS.) 
(See ICAO term AERODROME BEACON.) 
(Refer to AIM.) 

AIRPORT SURFACE DETECTION EQUIPMENT 
(ASDE)

  Surveillance equipment specifically de­

signed to detect aircraft, vehicular traffic, and other 
objects, on the surface of an airport, and to present the 
image on a tower display. Used to augment visual 
observation by tower personnel of aircraft and/or 
vehicular movements on runways and taxiways. 
There are three ASDE systems deployed in the NAS: 

a. 

ASDE

3

 a Surface Movement Radar. 

b. 

ASDE

X

 a system that uses an X

band 

Surface Movement Radar, multilateration, and 
ADS

B. 

c. 

Airport Surface Surveillance Capability 

(ASSC)

 A system that uses Surface Movement 

Radar, multilateration, and ADS

B. 

AIRPORT SURVEILLANCE RADAR

 Approach 

control radar used to detect and display an aircraft’s 
position in the terminal area. ASR provides range and 
azimuth information but does not provide elevation 
data. Coverage of the ASR can extend up to 60 miles. 

AIRPORT TAXI CHARTS

 

(See AERONAUTICAL CHART.) 

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.) 

AIS

 

(See AERONAUTICAL INFORMATION 

SERVICES.) 

AIT

 

(See AUTOMATED INFORMATION 

TRANSFER.) 

PCG A