Pilot/Controller Glossary 

6/17/21 

THRESHOLD CROSSING HEIGHT

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 The 

theoretical height above the runway threshold at 
which the aircraft’s glideslope antenna would be if 
the aircraft maintains the trajectory established by the 
mean ILS glideslope or the altitude at which the 
calculated glidepath of an RNAV or GPS approaches. 

(See GLIDESLOPE.) 

(See THRESHOLD.) 

THRESHOLD LIGHTS

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(See AIRPORT LIGHTING.) 

TIE-IN FACILITY– The FSS primarily responsible 
for providing FSS services, including telecommu-
n i ca t i o n s   s e rv i ce s   fo r   l a n d i n g   f ac i l i t i e s   o r  
navigational aids located within the boundaries of a 
flight plan area (FPA). Three-letter identifiers are 
assigned to each FSS/FPA and are annotated as tie-in 
facilities in the Chart Supplement U.S., the Alaska 
Supplement, the Pacific Supplement, and FAA Order 
JO 7350.9, Location Identifiers. Large consolidated 
FSS facilities may have many tie-in facilities or FSS 
sectors within one facility. 

(See FLIGHT PLAN AREA.) 

(See FLIGHT SERVICE STATION.) 

TIME

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BASED FLOW MANAGEMENT (TBFM)

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The hardware, software, methods, processes, and 
initiatives to manage air traffic flows based on time 
to balance air traffic demand with system capacity, 
and support the management of PBN.  This includes, 
but not limited to, Adjacent Center Metering (ACM), 
En Route Departure Capability (EDC), 
Ground

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based Interval Management-Spacing 

(GIM-S), Integrated Departure/Arrival Capability 
(IDAC), Single Center Metering (SCM), 
Time

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Based Metering (TBM), Time

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Based 

Scheduling (TBS), and Extended/Coupled Metering. 

TIME GROUP

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 Four digits representing the hour 

and minutes from the Coordinated Universal Time 
(UTC) clock. FAA uses UTC for all operations. The 
term “ZULU” may be used to denote UTC. The word 
“local” or the time zone equivalent shall be used to 
denote local when local time is given during radio and 
telephone communications. When written, a time 
zone designator is used to indicate local time; e.g., 
“0205M” (Mountain). The local time may be based 
on the 24-hour clock system. The day begins at 0000 
and ends at 2359. 

TIS

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B

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(See TRAFFIC INFORMATION 

SERVICE

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BROADCAST.) 

TMPA

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(See TRAFFIC MANAGEMENT PROGRAM 

ALERT.) 

TMU

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(See TRAFFIC MANAGEMENT UNIT.) 

TODA

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(See TAKEOFF DISTANCE AVAILABLE.) 
(See ICAO term TAKEOFF DISTANCE 

AVAILABLE.) 

TOI

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(See TRACK OF INTEREST.) 

TOP ALTITUDE

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 In reference to SID published 

altitude restrictions, the charted 

“

maintain” altitude 

contained in the procedure description or assigned by 
ATC. 

TORA

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(See TAKEOFF RUN AVAILABLE.) 
(See ICAO term TAKEOFF RUN AVAILABLE.) 

TORCHING

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 The burning of fuel at the end of an 

exhaust pipe or stack of a reciprocating aircraft 
engine, the result of an excessive richness in the fuel 
air mixture. 

TOS

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(See TRAJECTORY OPTIONS SET) 

TOTAL ESTIMATED ELAPSED TIME [ICAO]

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For IFR flights, the estimated time required from 
takeoff to arrive over that designated point, defined 
by reference to navigation aids, from which it is 
intended that an instrument approach procedure will 
be commenced, or, if no navigation aid is associated 
with the destination aerodrome, to arrive over the 
destination aerodrome. For VFR flights, the 
estimated time required from takeoff to arrive over 
the destination aerodrome. 

(See ICAO term ESTIMATED ELAPSED TIME.) 

TOUCH-AND-GO

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 An operation by an aircraft that 

lands and departs on a runway without stopping or 
exiting the runway. 

TOUCH-AND-GO LANDING

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(See TOUCH-AND-GO.) 

TOUCHDOWN

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a. 

The point at which an aircraft first makes 

contact with the landing surface. 

PCG T

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