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6/17/21 

Pilot/Controller Glossary 

TACAN

 

(See TACTICAL AIR NAVIGATION.) 

TACAN­ONLY AIRCRAFT

 An aircraft, normally 

military, possessing TACAN with DME but no VOR 
navigational system capability. Clearances must 
specify TACAN or VORTAC fixes and approaches. 

TACTICAL AIR NAVIGATION (TCAN)

 An 

ultra­high frequency electronic rho­theta air naviga­
tion aid which provides suitably equipped aircraft a 
continuous indication of bearing and distance to the 
TACAN station. 

(See VORTAC.) 
(Refer to AIM.) 

TAILWIND

 Any wind more than 90 degrees to the 

longitudinal axis of the runway. The magnetic 
direction of the runway shall be used as the basis for 
determining the longitudinal axis. 

TAKEOFF AREA

 

(See LANDING AREA.) 

TAKEOFF DISTANCE AVAILABLE (TODA)– The 
takeoff run available plus the length of any remaining 
runway or clearway beyond the far end of the takeoff 
run available. 

(See ICAO term TAKEOFF DISTANCE 

AVAILABLE.) 

TAKEOFF DISTANCE AVAILABLE [ICAO]

 The 

length of the takeoff run available plus the length of 
the clearway, if provided. 

TAKEOFF HOLD LIGHTS (THL)– The THL 
system is composed of in­pavement lighting in a 
double, longitudinal row of lights aligned either side 
of the runway centerline. The lights are focused 
toward the arrival end of the runway at the “line up 
and wait” point, and they extend for 1,500 feet in 
front of the holding aircraft. Illuminated red lights 
indicate to an aircraft in position for takeoff or rolling 
that it is unsafe to takeoff because the runway is 
occupied or about to be occupied by an aircraft or 
vehicle. 

TAKEOFF ROLL 

 The process whereby an aircraft 

is aligned with the runway centerline and the aircraft 
is moving with the intent to take off. For helicopters, 

this pertains to the act of becoming airborne after 
departing a takeoff area. 

TAKEOFF RUN AVAILABLE (TORA) – The 
runway length declared available and suitable for the 
ground run of an airplane taking off. 

(See ICAO term TAKEOFF RUN AVAILABLE.) 

TAKEOFF RUN AVAILABLE [ICAO]

 The length 

of runway declared available and suitable for the 
ground run of an aeroplane take­off. 

TARGET

 The indication shown on a display 

resulting from a primary radar return, a radar beacon 
reply, or an ADS

B report. The specific target 

symbol presented to ATC may vary based on the 
surveillance source and automation platform. 

(See ASSOCIATED.) 
(See DIGITAL TARGET.) 
(See DIGITIZED RADAR TARGET.) 
(See FUSED TARGET.) 
(See PRIMARY RADAR TARGET.) 
(See RADAR.) 
(See SECONDARY RADAR TARGET.) 
(See ICAO term TARGET.) 
(See UNASSOCIATED.) 

TARGET [ICAO]

 In radar: 

a. 

Generally, any discrete object which reflects or 

retransmits energy back to the radar equipment. 

b. 

Specifically, an object of radar search or 

surveillance. 

TARGET RESOLUTION

 A process to ensure that 

correlated radar targets do not touch. Target 
resolution must be applied as follows: 

a. 

Between the edges of two primary targets or the 

edges of the ASR­9/11 primary target symbol. 

b. 

Between the end of the beacon control slash and 

the edge of a primary target. 

c. 

Between the ends of two beacon control slashes. 

Note 1: Mandatory traffic advisories and safety 

alerts must be issued when this procedure is used. 

Note 2: This procedure must not be used when 

utilizing mosaic radar systems or multi

sensor 

mode. 

TARGET SYMBOL

 

(See TARGET.) 
(See ICAO term TARGET.) 

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