Pilot/Controller Glossary

(A-RNP), through tools that support the merging of mixed-equipage traffic flows. For example, merging aircraft
flying RNP APCH AR with RF, A-RNP, and non-RNP approach procedures. Additional fields in the flight plan
will identify those flights capable of flying the RNP APCH with RF or A-RNP procedures, and those flights
will be scheduled for those types of procedures when available. TSAS will schedule these and the non-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- 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
U.S.
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 CHART SUPPLEMENT U.S.)

TERMINAL-VERY HIGH FREQUENCY OMNIDIRECTIONAL RANGE STATION (TVOR)- 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.)

TFDM-
(See TERMINAL FLIGHT DATA MANAGER.)