TM 1-5855-265-20
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Section II. DEFINITION OF UNUSUAL TERMS
Afocal
- An optical system focused on infinity.
Avionics
- An acronym for aviation electronics.
Boresight
- The line-of-sight of a weapon sighting
instrument parallel to the axis of the
weapon bore.
Chafing
- Wear caused by friction or rubbing.
Fault Detection (FD/LS)
- Computer controlled built-in test (BIT) for
Location System
the helicopter and avionics.
Fixed Forward
- A position of the PNVS turret assembly
window such that it is lined up with
horizontal centerline of helicopter.
Flyaway Storage
- Storage items subject to immediate
flyaway.
Forward Looking
- Looking directly at infrared energy rather
than reflected infrared energy.
Image
A likeness of an object produced by
means of light rays.
Infrared
- Pertaining to radiations of heat from a
body or object
Line-of-Sight
- The straight line connecting the observer
with the aiming point; the line along
which a sight is set.
Maintenance Operational Check (MOC)
- A procedure used to determine opera-
tional status of equipment. It is performed
after a maintenance task and during trou-
bleshooting.
Nap-of-the-Earth (NOE)
- The technique of flying above the earth’s
terrain below 50 feet altitude and avoid-
ing terrain features.
Operator Interaction
- The use of semiautomatic equipment that
requires intervening actions by the opera-
tor.
Outgas
- The releasing of gases from a material
usually by heating. These gases can be
harmful to optics if the gases are trapped
in confined spaces.
Squat Switch
- A safety switch located near the helicop-
ter left main landing gear that disables
laser and anti-ice circuits while helicopter
is on the ground.
Tack Free
- Not sticking under pressure.
