4/20/23 

Pilot/Controller Glossary 

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TACAN

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(See TACTICAL AIR NAVIGATION.) 

TACAN-ONLY AIRCRAFT

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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 (TACAN)

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An ultra-high frequency electronic rho-theta air navigation aid 

which provides suitably equipped aircraft a continuous indication of bearing and distance to the TACAN station. 

(See VORTAC.) 
(Refer to AIM.) 

TAILWIND

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 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

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(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]

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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 in-pavement 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 

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 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]

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 The length of runway declared available and suitable for the ground 

run of an aeroplane take-off. 
TARGET

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 The indication shown on a display resulting from a primary radar return, a radar beacon reply, or an 

ADS

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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.) 

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