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Pilot/Controller Glossary 

6/17/21 

APRON

 A defined area on an airport or heliport 

intended to accommodate aircraft for purposes of 
loading or unloading passengers or cargo, refueling, 
parking, or maintenance. With regard to seaplanes, a 
ramp is used for access to the apron from the water. 

(See ICAO term APRON.) 

APRON [ICAO]

 A defined area, on a land 

aerodrome, intended to accommodate aircraft for 
purposes of loading or unloading passengers, mail or 
cargo, refueling, parking or maintenance. 

ARC

 The track over the ground of an aircraft flying 

at a constant distance from a navigational aid by 
reference to distance measuring equipment (DME). 

AREA CONTROL CENTER [ICAO]

 An air traffic 

control facility primarily responsible for ATC 
services being provided IFR aircraft during the en 
route phase of flight. The U.S. equivalent facility is 
an air route traffic control center (ARTCC). 

AREA NAVIGATION (RNAV)

 A method of 

navigation which permits aircraft operation on any 
desired flight path within the coverage of ground

 or 

space

based navigation aids or within the limits of 

the capability of self-contained aids, or a combination 
of these. 

Note: 

Area navigation includes performance

 

based navigation as well as other operations that 
do not meet the definition of performance

based 

navigation. 

AREA NAVIGATION (RNAV) APPROACH 
CONFIGURATION: 

a. 

STANDARD T

 An RNAV approach whose 

design allows direct flight to any one of three initial 
approach fixes (IAF) and eliminates the need for 
procedure turns. The standard design is to align the 
procedure on the extended centerline with the missed 
approach point (MAP) at the runway threshold, the 
final approach fix (FAF), and the initial approach/ 
intermediate fix (IAF/IF). The other two IAFs will be 
established perpendicular to the IF. 

b. 

MODIFIED T

 An RNAV approach design for 

single or multiple runways where terrain or 
operational constraints do not allow for the standard 
T. The “T” may be modified by increasing or 
decreasing the angle from the corner IAF(s) to the IF 
or by eliminating one or both corner IAFs. 

c. 

STANDARD I

 An RNAV approach design for 

a single runway with both corner IAFs eliminated. 

Course reversal or radar vectoring may be required at 
busy terminals with multiple runways. 

d. 

TERMINAL ARRIVAL AREA (TAA)

 The 

TAA is controlled airspace established in conjunction 
with the Standard or Modified T and I RNAV 
approach configurations. In the standard TAA, there 
are three areas: straight-in, left base, and right base. 
The arc boundaries of the three areas of the TAA are 
published portions of the approach and allow aircraft 
to transition from the en route structure direct to the 
nearest IAF. TAAs will also eliminate or reduce 
feeder routes, departure extensions, and procedure 
turns or course reversal. 

1. 

STRAIGHT-IN AREA

 A 30 NM arc 

centered on the IF bounded by a straight line 
extending through the IF perpendicular to the 
intermediate course. 

2. 

LEFT BASE AREA

 A 30 NM arc centered 

on the right corner IAF. The area shares a boundary 
with the straight-in area except that it extends out for 
30 NM from the IAF and is bounded on the other side 
by a line extending from the IF through the FAF to the 
arc. 

3. 

RIGHT BASE AREA

 A 30 NM arc 

centered on the left corner IAF. The area shares a 
boundary with the straight-in area except that it 
extends out for 30 NM from the IAF and is bounded 
on the other side by a line extending from the IF 
through the FAF to the arc. 

AREA NAVI GATION (R NAV) G L O B A L 
POSITIONING SYSTEM (GPS) PRECISION 
RUNWAY MONITORING (PRM) APPROACH– 
A GPS approach, which requires vertical guidance, 
used in lieu of another type of PRM approach to 
conduct approaches to parallel runways whose 
extended centerlines are separated by less than 4,300 
feet and at least 3,000 feet, where simultaneous close 
parallel approaches are permitted. Also used in lieu 
of an ILS PRM and/or LDA PRM approach to 
conduct Simultaneous Offset Instrument Approach 
(SOIA) operations. 

ARMY AVIATION FLIGHT INFORMATION 
BULLETIN

 A bulletin that provides air operation 

data covering Army, National Guard, and Army 
Reserve aviation activities. 

ARO

 

(See AIRPORT RESERVATION OFFICE.) 

ARRESTING SYSTEM

 A safety device consisting 

of two major components, namely, engaging or 

PCG A

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