5/19/22 

Pilot/Controller Glossary 

b. 

AGL Altitude

−

 Altitude expressed in feet 

measured above ground level. 

c. 

Indicated Altitude

−

 The altitude as shown by an 

altimeter. On a pressure or barometric altimeter it is 
altitude as shown uncorrected for instrument error 
and uncompensated for variation from standard 
atmospheric conditions. 

(See ICAO term ALTITUDE.) 

ALTITUDE [ICAO]

−

 The vertical distance of a level, 

a point or an object considered as a point, measured 
from mean sea level (MSL). 

ALTITUDE READOUT

−

  An aircraft’s altitude, 

transmitted via the Mode C transponder feature, that 
is visually displayed in 100-foot increments on a 
radar scope having readout capability. 

(See ALPHANUMERIC DISPLAY.) 
(See AUTOMATED RADAR TERMINAL 

SYSTEMS.) 

(Refer to AIM.) 

ALTITUDE RESERVATION (ALTRV)

−

 Airspace 

utilization under prescribed conditions normally 
employed for the mass movement of aircraft or other 
special user requirements which cannot otherwise be 
accomplished. ALTRVs are approved by the 
appropriate FAA facility. ALTRVs must be classified 
as either “moving” or “stationary.” 

(See MOVING ALTITUDE RESERVATION.) 
(See STATIONARY ALTITUDE RESERVATION.) 
(See AIR TRAFFIC CONTROL SYSTEM 

COMMAND CENTER.) 

ALTITUDE RESTRICTION

−

 An altitude or alti-

tudes, stated in the order flown, which are to be 
maintained until reaching a specific point or time. 
Altitude restrictions may be issued by ATC due to 
traffic, terrain, or other airspace considerations. 

ALTITUDE RESTRICTIONS ARE CANCELED

−

 

Adherence to previously imposed altitude restric-
tions is no longer required during a climb or descent. 

ALTRV

−

 

(See ALTITUDE RESERVATION.) 

AMVER

−

 

(See AUTOMATED MUTUAL-ASSISTANCE 

VESSEL RESCUE SYSTEM.) 

APB

−

 

(See AUTOMATED PROBLEM DETECTION 

BOUNDARY.) 

APD

−

 

(See AUTOMATED PROBLEM DETECTION.) 

APDIA

−

 

(See AUTOMATED PROBLEM DETECTION 

INHIBITED AREA.) 

APPROACH CLEARANCE

−

 Authorization by 

ATC for a pilot to conduct an instrument approach. 
The type of instrument approach for which a 
clearance and other pertinent information is provided 
in the approach clearance when required. 

(See CLEARED APPROACH.) 
(See INSTRUMENT APPROACH 

PROCEDURE.) 

(Refer to AIM.) 
(Refer to 14 CFR Part 91.) 

APPROACH CONTROL FACILITY

−

 A terminal 

ATC facility that provides approach control service in 
a terminal area. 

(See APPROACH CONTROL SERVICE.) 
(See RADAR APPROACH CONTROL 

FACILITY.) 

APPROACH CONTROL SERVICE

−

 Air traffic 

control service provided by an approach control 
facility for arriving and departing VFR/IFR aircraft 
and, on occasion, en route aircraft. At some airports 
not served by an approach control facility, the 
ARTCC provides limited approach control service. 

(See ICAO term APPROACH CONTROL 

SERVICE.) 

(Refer to AIM.) 

APPROACH CONTROL SERVICE [ICAO]

−

 Air 

traffic control service for arriving or departing 
controlled flights. 

APPROACH GATE

−

 An imaginary point used 

within ATC as a basis for vectoring aircraft to the 
final approach course. The gate will be established 
along the final approach course 1 mile from the final 
approach fix on the side away from the airport and 
will be no closer than 5 miles from the landing 
threshold. 

APPROACH/DEPARTURE HOLD AREA

−

 The 

locations on taxiways in the approach or departure 
areas of a runway designated to protect landing or 
departing aircraft. These locations are identified by 
signs and markings. 

APPROACH LIGHT SYSTEM

−

 

(See AIRPORT LIGHTING.) 

PCG A

−

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