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Pilot/Controller Glossary 

THAT IS CORRECT

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The understanding you have is right. 

THA

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(See TRANSITIONAL HAZARD AREA.) 

THE RECREATIONAL UAS SAFETY TEST (TRUST)

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 The electronically administered free test required for 

all recreational UAS operators referred to as the aeronautical knowledge and safety test, under 49 USC §44809 

(g). 
THREE

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HOUR TARMAC RULE– Rule that relates to Department of Transportation (DOT) requirements 

placed on airlines when tarmac delays are anticipated to reach 3 hours. 
360 OVERHEAD

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(See OVERHEAD MANEUVER.) 

THRESHOLD

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 The beginning of that portion of the runway usable for landing. 

(See AIRPORT LIGHTING.) 
(See DISPLACED THRESHOLD.) 

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 telecommunica-

tions services for landing facilities or 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 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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 A foundational Decision Support Tool for time

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based 

management in the en route and terminal environments. TBFM’s core function is the ability to schedule aircraft 

within a stream of traffic to reach a defined constraint point (e.g., meter fix/meter arc) at specified times, creating 

a time

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ordered sequence of traffic. The scheduled times allow for merging of traffic flows, efficiently utilizing 

airport and airspace capacity while minimizing coordination and reducing the need for vectoring/holding. The 

TBFM schedule is calculated using current aircraft estimated time of arrival at key defined constraint points 

based on wind forecasts, aircraft flight plan, the desired separation at the constraint point and other parameters. 

The schedule applies spacing only when needed to maintain the desired separation at one or more constraint 

points. This includes, but is not limited to, Single Center Metering (SCM), Adjacent Center Metering (ACM), 

En Route Departure Capability (EDC), Integrated Departure/Arrival Capability (IDAC), Ground

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based Interval 

Management

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Spacing (GIM

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S), Departure Scheduling, and Extended/Coupled Metering. 

TIME

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BASED MANAGEMENT (TBM)

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 A methodology for managing the flow of air traffic through the 

assignment of time at specific points for an aircraft. TBM applies time to manage and condition air traffic flows 

to mitigate demand/capacity imbalances and enhance efficiency and predictability of the NAS. Where 

implemented, TBM tools will be used to manage traffic even during periods when demand does not exceed 

capacity. This will sustain operational predictability and assure the regional/national strategic plan is maintained. 

TBM uses capabilities within TFMS, TBFM, and TFDM. These programs are designed to achieve a specified 

interval between aircraft. Different types of programs accommodate different phases of flight. 
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 

PCG T

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