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Pilot/Controller Glossary 

6/17/21 

TRANSITION WAYPOINT

 The waypoint that 

defines the beginning of a runway or en route 
transition on an RNAV SID or STAR. 

TRANSITIONAL AIRSPACE

 That  portion of 

controlled airspace wherein aircraft change from one 
phase of flight or flight condition to another. 

TRANSITIONAL HAZARD AREA (THA)

 Used 

by ATC. Airspace normally associated with an 
Aircraft Hazard Area within which the flight of 
aircraft is subject to restrictions. 

(See AIRCRAFT HAZARD AREA.) 
(See CONTINGENCY HAZARD AREA.) 
(See REFINED HAZARD AREA.) 

TRANSMISSOMETER

 An apparatus used to 

determine visibility by measuring the transmission of 
light through the atmosphere. It is the measurement 
source for determining runway visual range (RVR). 

(See VISIBILITY.) 

TRANSMITTING IN THE BLIND

  A transmis-

sion from one station to other stations in 
circumstances where two-way communication 
cannot be established, but where it is believed that the 
called stations may be able to receive the 
transmission. 

TRANSPONDER

 The airborne radar beacon 

receiver/transmitter portion of the Air Traffic Control 
Radar Beacon System (ATCRBS) which automati-
cally receives radio signals from interrogators on the 
ground, and selectively replies with a specific reply 
pulse or pulse group only to those interrogations 
being received on the mode to which it is set to 
respond. 

(See INTERROGATOR.) 
(See ICAO term TRANSPONDER.) 
(Refer to AIM.) 

TRANSPONDER [ICAO]

 A receiver/transmitter 

which will generate a reply signal upon proper 
interrogation; the interrogation and reply being on 
different frequencies. 

TRANSPONDER CODES

 

(See CODES.) 

TRANSPONDER OBSERVED 

 Phraseology used 

to inform a VFR pilot the aircraft

s assigned beacon 

code and position have been observed. Specifically, 
this term conveys to a VFR pilot the transponder 

reply has been observed and its position correlated for 
transit through the designated area. 

TRIAL PLAN

 A proposed amendment which 

utilizes automation to analyze and display potential 
conflicts along the predicted trajectory of the selected 
aircraft. 

TRSA

 

(See TERMINAL RADAR SERVICE AREA.) 

TSD

 

(See TRAFFIC SITUATION DISPLAY.) 

TURBOJET AIRCRAFT

 An aircraft having a jet 

engine in which the energy of the jet operates a 
turbine which in turn operates the air compressor. 

TURBOPROP AIRCRAFT

 An aircraft having a jet 

engine in which the energy of the jet operates a 
turbine which drives the propeller. 

TURBULENCE

 An atmospheric phenomenon that 

causes changes in aircraft altitude, attitude, and or 
airspeed with aircraft reaction depending on 
intensity. Pilots report turbulence intensity according 
to aircraft’s reaction as follows: 

a. 

Light 

 Causes slight, erratic changes in altitude 

and or attitude (pitch, roll, or yaw). 

b. 

Moderate

 Similar to Light but of greater 

intensity. Changes in altitude and or attitude occur 
but the aircraft remains in positive control at all times. 
It usually causes variations in indicated airspeed. 

c. 

Severe

 Causes large, abrupt changes in altitude 

and or attitude. It usually causes large variations in 
indicated airspeed. Aircraft may be momentarily out 
of control. 

d. 

Extreme

 The aircraft is violently tossed about 

and is practically impossible to control. It may cause 
structural damage. 

(See CHOP.) 
(Refer to AIM.) 

TURN ANTICIPATION

 (maneuver anticipation). 

TVOR

 

(See TERMINAL-VERY HIGH FREQUENCY 

OMNIDIRECTIONAL RANGE STATION.) 

TWO-WAY RADIO COMMUNICATIONS FAIL-
URE

 

(See LOST COMMUNICATIONS.) 

PCG T