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Pilot/Controller Glossary 

b. 

Nonprecision instrument. 

c. 

Precision instrument. 

(Refer to AIM.) 

AIRPORT REFERENCE POINT (ARP)

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 The approximate geometric center of all usable runway surfaces. 

AIRPORT RESERVATION OFFICE

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Office responsible for monitoring the operation of slot controlled 

airports. It receives and processes requests for unscheduled operations at slot controlled airports. 
AIRPORT ROTATING BEACON

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A visual NAVAID operated at many airports. At civil airports, alternating 

white and green flashes indicate the location of the airport. At military airports, the beacons flash alternately 

white and green, but are 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 designed 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

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B. 

c. 

Airport Surface Surveillance Capability (ASSC)

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 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: 

PCG A

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