the Aviation Dictionary

terminal very high frequency ornni-directional range station (TVOR) . thermal circuit breaker
terminal very high frequency omni-directional range
station (TVOR)- A very high frequency terminal
omni-range station located on or near an airport and
used as an approach aid.
terminal VFR radar sewice - A national program
instituted to extend the terminal radar services provided
instrument flight rules (IFR) aircraft to visual flight
rules (VFR) aircraft. The program is divided into four
types of service referred to as basic radar service,
terminal radar service area (TRSA) service, Class B
service and Class C service. The type of service
provided at a particular location is contained in the
AirportiFacility Directory.
a. Basic Radar Service: These services are provided for
VFR aircraft by all commissioned terminal radar
facilities. Basic radar service includes safety alerts,
traffic advisories, limited radar vectoring when
requested by the pilot, and sequencing at locations
where procedures have been established for this
purpose and/or when covered by a letter of agreement.
The purpose of this service is to adjust the flow of
arriving IFR and VFR aircraft into the traffic pattern in
a safe and orderly manner and to provide traffic
advisories to departing VFR aircraft.
b. TRSA Service: This service provides, in addition to
basic radar service, sequencing of all IFR and
participating VFR aircraft to the primary airport and
separation between all participating VFR aircraft. The
purpose of this service is to provide separation between
all participating VFR aircraft and all IFR aircraft
operating within the area defined as a TRSA.
c. Class C Service: This service provides, in addition to
basic radar service, approved separation between IFR
and VFR aircraft, sequencing of VFR aircraft, and
sequencing of VFR arrivals to the primary airport.
d. Class B Service: This service provides, in addition to
basic radar service, approved separation of aircraft
based on IFR, VFR, and/or weight, and sequencing of
VFR arrivals to the primary airport(s).
terminal voltage - The potential difference or voltage
across the terminals of a power supply such as a battery
of cells. As soon as the power source begins to supply
current to a circuit its terminal voltage falls because
some electric potential energy is lost in driving current
against the supply's own internal resistance.
terminating decimal - A decimal fraction that ends
with a whole number.
terneplate - Lead-coated thin sheets of steel used in
some older aircraft for the construction of fuel tanks
and for the tipping on their wooden propellers.
terrestrial radiation - The radiation emitted by the
Earth and its atmosphere.
tertiary - Something at a third level of importance.
rank, or value.
test - 1. To submit a unit, component, etc. to conditions
that will show its quality, strength, etc. 2. A set of
questions, problems or exercises for determining
whether a person has a particular knowledge or skill.
test club - A wide-blade, short-diameter propeller used
for applying a load to a freshly overhauled aircraft
engine for its initial run-in.
test item - A question, problem, or exercise that
measures a single objective and calls for a single
response.
test stand - A stationary structure where engines, units,
components, etc., can be mounted for testing.
test switch - A switch used to test a system in order to
determine its operational condition.
tetraethyl lead - A heavy, oily, poisonous liquid
(Pb(C2H&) mixed into aviation gasoline to increase its
octane rating.
tetrahedron - A device normally located on
uncontrolled airports and used as a landing direction
indicator. The small end of a tetrahedron points in the
direction of landing. At controlled airports, the
tetrahedron, if installed, should be disregarded because
tower instructions supersede the indicator.
tetrode -An
electron tube having four active electrodes.
T-handle - A T-shaped handle used for turning sockets.
that is correct - During communications, this indicates:
The understanding you have is right.
theodolite - An optical instrument used to measure
vertical and horizontal angles. Theodolites are used for
surveying and weather observations.
theoretical pitch - An assumed pitch of the propeller
blades. Also referred to as as geometric pitch.
therapeutic adapter - An adapter for a continuous-flow
oxygen mask that allows oxygen to flow approximately
three times the normal rate. It is used for passengers
that have heart or respiratory problems.
thermal - Rising air that lifts because it is warmer than
surrounding air.
thermal anti-icing system - A heated leading edge of
the wing and tail surfaces to prevent the formation of
.-.. ice.
terrain following - The flight of a military aircraft
maintaining a constant A ~ altitude L above the terrain thermal circuit breaker -A circuit breaker that opens a
or the highest obstruction. The altitude of the aircraft circuit when an excessive amount of current flows
will constantly change with the varying terrain and/or through it. Made up of a bimetallic set of contacts that
obstruction.
open when heated.
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