Pilot/Controller Glossary

4/3/14

PCG T−3

TRSAs are depicted on VFR aeronautical charts.

Pilot participation is urged but is not mandatory.
TERMINAL VFR RADAR SERVICE− 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 Airport/Facility Directory.

a.

Basic Radar Service− 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− 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− 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− 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 AIRPORT/FACILITY DIRECTORY.)

TERMINAL-VERY HIGH FREQUENCY OMNI-

DIRECTIONAL RANGE STATION− 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)− An on−board, terrain proximity alerting

system providing the aircrew ‘Low Altitude

warnings’ to allow immediate pilot action.
TERRAIN FOLLOWING− 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− 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−

(See TERRAIN FOLLOWING.)

THAT IS CORRECT

− The understanding you have

is right.
THREE−HOUR TARMAC RULE– Rule that relates

to Department of Transportation (DOT) requirements

placed on airlines when tarmac delays are anticipated

to reach 3 hours.
360 OVERHEAD−

(See OVERHEAD MANEUVER.)

THRESHOLD− The beginning of that portion of the

runway usable for landing.

(See AIRPORT LIGHTING.)
(See DISPLACED THRESHOLD.)

THRESHOLD CROSSING HEIGHT− The theoreti-

cal height above the runway threshold at which the

aircraft’s glideslope antenna would be if the aircraft

maintains the trajectory established by the mean ILS

glideslope or MLS glidepath.

(See GLIDESLOPE.)
(See THRESHOLD.)

THRESHOLD LIGHTS−

(See AIRPORT LIGHTING.)

TIBS−

(See TELEPHONE INFORMATION BRIEFING

SERVICE.)

TIE-IN FACILITY– The FSS primarily responsible

for providing FSS services, including telecommu-

nications services for landing facilities or