Pilot/Controller Glossary 

3/21/24 

(A

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RNP), through tools that support the merging of mixed

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equipage traffic flows. For example, merging aircraft 

flying RNP APCH AR with RF, A

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RNP, and non

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RNP approach procedures. Additional fields in the flight plan 

will identify those flights capable of flying the RNP APCH with RF or A

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RNP procedures, and those flights 

will be scheduled for those types of procedures when available. TSAS will schedule these and the non

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RNP 

aircraft to a common merge point. Terminal traffic management personnel have improved situation awareness 

using displays that allow for the monitoring of terminal metering operations, similar to the displays used today 

by center traffic management personnel to monitor en route metering operations. 
TERMINAL VFR RADAR SERVICE

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 A national program instituted to extend the terminal radar services 

provided instrument flight rules (IFR) aircraft to visual flight rules (VFR) aircraft. The program is divided into 

four types service referred to as basic radar service, terminal radar service area (TRSA) service, Class B service 

and Class C service. The type of service provided at a particular location is contained in the Chart Supplement. 

a. 

Basic Radar Service

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 These services are provided for VFR aircraft by all commissioned terminal radar 

facilities. Basic radar service includes safety alerts, traffic advisories, limited radar vectoring when requested 

by the pilot, and sequencing at locations where procedures have been established for this purpose and/or when 

covered by a letter of agreement. The purpose of this service is to adjust the flow of arriving IFR and VFR aircraft 

into the traffic pattern in a safe and orderly manner and to provide traffic advisories to departing VFR aircraft. 

b. 

TRSA Service

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 This service provides, in addition to basic radar service, sequencing of all IFR and 

participating VFR aircraft to the primary airport and separation between all participating VFR aircraft. The 

purpose of this service is to provide separation between all participating VFR aircraft and all IFR aircraft 

operating within the area defined as a TRSA. 

c. 

Class C Service

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 This service provides, in addition to basic radar service, approved separation between IFR 

and VFR aircraft, and sequencing of VFR aircraft, and sequencing of VFR arrivals to the primary airport. 

d. 

Class B Service

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 This service provides, in addition to basic radar service, approved separation of aircraft 

based on IFR, VFR, and/or weight, and sequencing of VFR arrivals to the primary airport(s). 

(See CONTROLLED AIRSPACE.) 
(See TERMINAL RADAR SERVICE AREA.) 
(Refer to AIM.) 
(Refer to CHART SUPPLEMENT U.S.) 

TERMINAL-VERY HIGH FREQUENCY OMNIDIRECTIONAL RANGE STATION (TVOR)

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 A very high 

frequency terminal omnirange station located on or near an airport and used as an approach aid. 

(See NAVIGATIONAL AID.) 
(See VOR.) 

TERRAIN AWARENESS WARNING SYSTEM (TAWS)

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 An on

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board, terrain proximity alerting system 

providing the aircrew ‘Low Altitude warnings’ to allow immediate pilot action. 
TERRAIN FOLLOWING

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 The flight of a military aircraft maintaining a constant AGL altitude above the terrain 

or the highest obstruction. The altitude of the aircraft will constantly change with the varying terrain and/or 

obstruction. 
TETRAHEDRON

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 A device normally located on uncontrolled airports and used as a landing direction indicator. 

The small end of a tetrahedron points in the direction of landing. At controlled airports, the tetrahedron, if 

installed, should be disregarded because tower instructions supersede the indicator. 

(See SEGMENTED CIRCLE.) 
(Refer to AIM.) 

TF

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(See TERRAIN FOLLOWING.) 

TFDM

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(See TERMINAL FLIGHT DATA MANAGER.) 

TGUI

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(See TIMELINE GRAPHICAL USER INTERFACE.) 

PCG T

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