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Uniter
length or other undistorted measure; ie deformation per
unit of original length.
Uniter Secure survivable fixed telecom network, part of
DFTS and particularly linking UKAdge (RAF).
unit hydraulic tail Power unit driving tailplane (horizontal
stabilizer, taileron).
unit load Also called unitized load, any collection of
cargo items packaged to fit a unit load device.
unit load device Platform or container for cargo, of
standard ISO dimensions and interfacing with handling
and restraint systems, e.g., LD3 container or 88×125
pallet.
unit of action C 2 vehicle Provides situational awareness
to land and air component commanders, sending highresolution
targeting via AOC9 by datalink.
unit of issue Measure in which commodity (esp. military)
is issued, eg by number, dozens, metres, feet, US gal
etc.
units of measurement See unit (1). In most practical
flying SI is still unattained, distances being in nautical
miles, pressures in lb/sq in, atmos, bar and various other
units (hardly ever Pa), acceleration in g, and volumes in
litres, US gal or Imp. gal instead of m 3 (but fuel mass
generally in kg).
unit stress Usually load divided by cross-section area
normal to applied force direction.
unit training device Simulator.
universal gas constant See gas constant.
Universal Metrics A set of six performance measures
designed to be applicable across the UK [and thus
probably any other] aerospace industry, launched in 2002
by the SBAC Lean Aerospace Initiative. The objective is
to enable companies to measure their performance and
that of their supply chain.
universal motor Electric motor operative on a.c. or d.c.
universal polar stereographic Grid for regions from 80°
latitude to poles.
universal receiver Operative on a.c. or d.c., with various
protective devices.
Universal Safety Oversight Audit Inspection by ICAOled
team of safety and security measures taken by 187
member states to counter terrorism.
universal shunt Resistor in parallel with ammeter to
increase range of currents measured as FSD is
approached.
universal tester Usually, hand meter for measuring
a.c./d.c. current, a.c./d.c. volts and resistances.
universal time Defined by rotation of Earth, and thus
not absolutely uniform; ** 1, corrected for polar motion;
** 2, corrected for seasonal variation in rotation.
universal timing disc Disc graduated 000°/360° with
associated pendulous pointer, attached to piston-engine
crankshaft.
universal transmission function Attempts to describe
mathematically IR propagation in atmosphere.
universal transverse Mercator Grid co-ordinate system
from 84°N to 80°S.
UNK, unk, unkn Unknown.
unknown traffic Flight details not known to the ATSU
with which you are in contact.
UNL Unlimited (altitude, ceiling).
unlgtd Unlighted (FAA).
Unlimited 1 Air race class for piston-engined aircraft: no
restriction on engine capacity.
unstable air
2 Aerobatic class: no restriction is imposed on flight
manoeuvres apart from airframe strength limits.
unlimited ceiling Traditionally, less than 50% cloud,
base 9,750+ft (2,972 m) AGL (FAA).
unload To reduce g (normal acceleration), usually to
restore lost speed.
unloading See pump unloading.
unlocked Automatic-gun action in which at moment of
firing breech is not locked (eg to barrel or case) but is of
sufficient mass (inertia) for pressure to have fallen to safe
level before breech opens significantly; usually synonymous
with blowback action.
unltd Unlimited.
unmanned Aircraft has no pilot on board [but may have
one in another aircraft or on ground].
unmask Point at which vehicle becomes visible to
defending surveillance systems.
unmkd Unmarked (eg obstruction) (FAA).
Unmovic UN Monitoring, Verification and Inspection
Commission.
UN No Four-digit number identifying a particular
dangerous material in cargo.
UNOSC UN Outer Space Committee.
unpaired channel DME channel without a corresponding
VOR or ILS frequency.
unprepared airfield Usual meaning is without permanent
paved runway.
unpumpable fuel That fuel deliberately designed to be
unpumpable, through levels of sumps and booster-pump
inlet sills, to avoid ingestion of any water.
unrefuelled range Range on fuel carried at takeoff;
usually applied to aircraft with provision for inflight
refuelling.
unreinforced ablator Without honeycomb filling or
backing.
unrel Unreliable.
unreliability coding Series of (usually five) dots
following transmissions made by unusable Tacan for calibration
or test purposes, indicating not to be used.
unrotated projectile Original name for unguided air and
ground-launched rockets (UK, WW2).
UNRSTD Unrestricted.
UNSA Unmanned naval strike aircraft [projects].
unscheduled maintenance Those unpredictable maintenance
requirements not previously planned or
programmed but which require prompt attention and
must be added to, integrated with or substituted for
previously scheduled workloads (USAF).
unsealed strip Runway with no waterproof coating;
normally means compacted earth, gravel or other
substrate with or without top layer of rolled material or
prefabricated mat of mesh or steel planking.
unshielded A major meaning is that portion of aerodynamic
surface in full slipstream, not in wake of another
part of aircraft, especially that part of rudder not in wake
from horizontal tail in established spin. The URVC is
based on this multiplied by its moment arm.
Unspec Unspecified.
unstable aerofoil Generally means one with extensive CP
travel.
unstable air Air in which temperature decreases with
height at rate greater than DALR or SALR; thus a parcel
given a small vertical movement (up or down) will
continue with increasing speed.
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