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Pilot/Controller Glossary 

b. 

Concerning a precision radar approach (PAR), it is the point where the glide path intercepts the landing 

surface. 

(See ICAO term TOUCHDOWN.) 

TOUCHDOWN [ICAO]

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 The point where the nominal glide path intercepts the runway. 

Note: Touchdown as defined above is only a datum and is not necessarily the actual point at which the aircraft 

will touch the runway. 

TOUCHDOWN RVR

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(See VISIBILITY.) 

TOUCHDOWN ZONE

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 The first 3,000 feet of the runway beginning at the threshold. The area is used for 

determination of Touchdown Zone Elevation in the development of straight-in landing minimums for instrument 

approaches. 

(See ICAO term TOUCHDOWN ZONE.) 

TOUCHDOWN ZONE [ICAO]

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 The portion of a runway, beyond the threshold, where it is intended landing 

aircraft first contact the runway. 
TOUCHDOWN ZONE ELEVATION

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 The highest elevation in the first 3,000 feet of the landing surface. TDZE 

is indicated on the instrument approach procedure chart when straight-in landing minimums are authorized. 

(See TOUCHDOWN ZONE.) 

TOUCHDOWN ZONE LIGHTING

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(See AIRPORT LIGHTING.) 

TOWER

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A terminal facility that uses air/ground communications, visual signaling, and other devices to 

provide ATC services to aircraft operating in the vicinity of an airport or on the movement area. Authorizes 

aircraft to land or takeoff at the airport controlled by the tower or to transit the Class D airspace area regardless 

of flight plan or weather conditions (IFR or VFR). A tower may also provide approach control services (radar 

or nonradar). 

(See AIRPORT TRAFFIC CONTROL SERVICE.) 
(See APPROACH CONTROL FACILITY.) 
(See APPROACH CONTROL SERVICE.) 
(See MOVEMENT AREA.) 
(See TOWER EN ROUTE CONTROL SERVICE.) 
(See ICAO term AERODROME CONTROL TOWER.) 
(Refer to AIM.) 

TOWER EN ROUTE CONTROL SERVICE

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The control of IFR en route traffic within delegated airspace 

between two or more adjacent approach control facilities. This service is designed to expedite traffic and reduce 

control and pilot communication requirements. 
TOWER TO TOWER

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(See TOWER EN ROUTE CONTROL SERVICE.) 

TRACEABLE PRESSURE STANDARD

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 The facility station pressure instrument, with certification/calibra-

tion traceable to the National Institute of Standards and Technology. Traceable pressure standards may be 

mercurial barometers, commissioned ASOS or dual transducer AWOS, or portable pressure standards or DASI. 
TRACK

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 The actual flight path of an aircraft over the surface of the earth. 

(See COURSE.) 
(See FLIGHT PATH.) 
(See ROUTE.) 
(See ICAO term TRACK.) 

TRACK [ICAO]

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 The projection on the earth’s surface of the path of an aircraft, the direction of which path at 

any point is usually expressed in degrees from North (True, Magnetic, or Grid). 

PCG T

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