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terrain-avoidance system
terrain-avoidance system System, usually radar-based,
providing pilot or other crew member with situation
display of ground or obstacles ahead which project above
either horizontal plane parallel to aircraft or plane
containing aircraft pitch/roll axes so that pilot can
manoeuvre aircraft laterally to avoid obstruction. Radar
becomes primary flight instrument.
terrain board Physical model of landscape formerly used
in simulation of air activity.
terrain-clearance system System, usually radar-based,
providing pilot or autopilot with climb/dive signals such
that aircraft maintains preset flight level while clearing
peaks within selected height in vertical plane through
flight vector. Unlike terrain-following, after each
protruding peak aircraft levels out at prescribed FL.
terrain comparison See Tercom.
terrain database Comprises computer-stored 2-D grid of
ground spot heights plus land culture information.
terrain-following system System, usually radar-based,
which provides pilot or autopilot with climb/dive signals
such that aircraft will maintain as closely as possible a
selected lo height above ground contour in vertical plane
through flight vector. In effect system projects radar skitoe
locus which slides over terrain ahead to give minimum
safe clearance.
terrain masking Obscuration of aerial and other targets
by hills or buildings, esp. as seen at acute grazing angles
by overland downlook radar.
terrain orientation Holding topographical map so that
aircraft heading is at top of sheet or folded sheet.
terrain profile Outline of profile of ground surface,
usually with vertical scale × 5 (sometimes × 10) published
on approach chart or other documents to assist pilots.
terrain-profile recorder Airborne instrument, recording
sensitive radar or laser altimeter, giving hard-copy
readout for mapping and surveying.
terrain-referenced navigation Terrestrial reference
guidance.
terrestrial radiation Earth IR radiation; also called
eradiation.
terrestrial reference guidance Any method providing
steering intelligence from characteristics (usually stored as
quantified digital measures) of surface being overflown,
thereby achieving flight along a predetermined path
without the need for emissions. One example is Tercom.
Also called terrain-reference [or referenced] navigation.
terrestrial refraction Refraction observed in light from
source within Earth atmosphere; thus caused only by
inhomogeneities of atmosphere itself.
terrestrial scintillation Generalized term for scintillation
effects observed in light from sources within Earth atmosphere;
also called atmospheric boil, optical haze and
shimmer.
Tersi Series of EW jamming and aerial-pattern
simulators.
tertiary airflow That passing through tertiary holes.
tertiary holes Apertures in gas-turbine flame tube or
combustor downstream of secondary holes admitting air
purely for dilution and cooling purposes to achieve
desired uniform gas temperature across chamber exit
plane.
tertiary initiation Impact with Earth’s surface, especially
land (NW).
TERTM Thermal-expansion resin transfer machine.
test vehicle
TES 1 Test and evaluation squadron.
2 Technology Experiment Satellite (India).
3 Tactical environment, or engagement, simulation [or
system].
4 Thermal emission spectrometer.
5 Transportable Earth station.
6 Threat-emitter system.
7 Trials end system (ATN).
8 Total engine support.
9 See next.
TES-A Tactical Exploitation System-Army [EA-6B]
(USN).
TESAC, Tesac Training and evaluation system for
active countermeasures.
Tesar 1 Tactically enhanced synthetic-aperture radar.
2 Tactical-endurance synthetic-aperture radar (UAV)
or search and rescue.
tesla SI unit of magnetic flux density; 1T = 1 Wb/m 2 =
10 4 G.
tesla coil Induction coil without iron core normally
giving HF output.
TES-N Tactical exploitation system – Navy (USN).
Tess 1 Tactical engagement, or threat-emitter, simulation
system.
2 Transport efficiency support system.
Test Checklist at start of takeoff: time, engine instruments,
strobe, transponder.
testbed Mounting, either on ground or in form of
aircraft, upon which item can be mounted or installed for
test purposes. When an aircraft may be, but not necessarily,
prefixed by ‘flight’ or ‘flying’. In US normally
called test stand.
test cell Usually horizontal test stand, eg for rocket
motor, surrounded except on operative side by protective
shelter giving protection from weather and limited protection
externally from explosion inside.
test chamber Environmentally controlled sealed
chamber in which test can take place; eg can simulate
stratosphere or hard vacuum with space solar radiation.
test clip Spring-steel clip for quick electrical connections
to terminals.
test club Club propeller making no pretence at aerofoil
shape but merely having stubby projecting arms in correct
balance.
test diamond Region in supersonic tunnel working
section within which model is placed and within which
flow conditions are essentially constant at any one time.
test firing Firing of rocket, of any type, while mounted
on testbed (test stand).
test flight Flight by aircraft, winged spacecraft or cruise
missile for purpose of evaluating or measuring performance,
handling or system operation.
test pattern Geometric pattern used in testing electronic
displays.
test program[me] set Small box which is brought to
check out cockpit processors.
test rig See rig (3).
test section 1 Tunnel working section.
2 Special glove aerofoil carried on flying testbed.
test set Packaged equipment, either versatile or for
testing specific system, of electronic, hydraulic, pneumatic,
microwave/RF or any other character, which can
readily be brought to aircraft or have device brought to it.
test vehicle Air vehicle, normally unmanned, built to test
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