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ATIC
2 Anti-trust immunity [DoT] (US).
3 Air Technical Intelligence (USAAF, USAF).
ATIC Avionics Test and Integration Complex
(Edwards AFB).
ATIF 1 Aeronautical telecommunications network
trials infrastructure (ICAO).
2 All-source track and identification fusion.
ATIG Air Technical Intelligence Group, of FEAF
(1945–6).
Atigs Advanced tactical inertial guidance system.
ATILO Air technical-intelligence liaison officer.
ATIMS Airborne target-information management
system.
ATIMU Advanced tactical inertial-measurement unit.
ATIR Air-traffic incident report.
ATIRCM Advanced threat, or theatre, IR countermeasures.
ATIS 1 Automatic, or automated, terminal information
service (ICAO, FAA); continuous broadcast of
recorded non-control information in selected highactivity
terminal areas (to improve controller
effectiveness, and relieve congestion by automating
repetitive transmission of routine information.
2 Airfield-terminal information system.
3 Air-traffic information service, or server, or system.
ATISD Air Training Information Systems Division
(Randolph AFB).
ATITA Air Transport Industry Training Association
(UK).
ATITB Aviation and Travel Industry Training Board
(NZ).
ATK Aviation turbine kerosene; F adds fuel.
ATKHB Attack Helicopter Battalion (USA).
ATk 1 Available tonne-kilometres.
2 Anti-tank.
ATL 1 Airborne, or advanced, tactical laser.
2 Auto-trim loop.
3 Acquisition, technology and logistics (DoD).
4 Automatic tape layer, or tapelaying.
ATLA Air Transport Licensing Authority (Hong
Kong, formerly).
Atlantic Airborne targeting low-altitude navigation
thermal imaging and cueing.
Atlas 1 Abbreviated test language for avionics systems.
2 Advanced tactical low arresting system (overrun
barrier).
3 Advanced tactical light arresting system (Aerazur
cable/drum).
4 Advanced-technology ladar system.
5 Airborne topography and land-use assessment
system.
6 Azimuth target-intelligence and acquisition system
(Israel).
7 Antenna-testing laboratory automated system (NAS
Patuxent).
8 Aircraft total lightning advisory system.
Atlass Advanced technology low-altitude surveillance
system.
ATLB Air Transport Licensing Board (UK).
Atlis Automatic tracking laser illumination system.
ATLND Automatic takeoff and landing (UAV).
ATM 1 Air-turbine motor.
2 Air transport movement, or management.
atmospheric electric field
3 Air tasking [previously base] message, request for a
particular combat mission to be flown (RAF).
4 Anti-tactical missile.
5 Anti-tank missile, or mine, or munition.
6 Asynchronous transfer, or transmission, mode.
7 Airspace, or air, [and] traffic management [C adds
centre, MG management group].
8 Aileron trim motor.
9 Air-targeting mode.
atm Atmospheres pressure (UK usage, see ata).
ATMA 1 Association Technique Maritime et
Aéronautique (F).
2 Active tuned mass absorber.
Atmac Air Traffic Management Advisory Committee
(RTCA).
ATMDC Air Traffic Management Development Centre
[Christchurch BT23 6DF] (UK).
ATMG Arms Transfer Management Group (US DoD).
Atmos Ammunition, toxic material open space.
atmosphere 1 Gaseous envelope surrounding Earth,
subdivided into layers (see atmospheric regions, model
atmosphere). For composition see Air.
2 Gaseous or vaporous envelope surrounding other
planets and celestial bodies.
3 Theoretical model atmosphere providing standard
basis for performance and other calculation.
4 Any of group of units of pressure all approximately
equal to pressure of atmosphere on Earth at sea level.
Most important is Standard * (abb. ata on European
continent, atm in UK) equal to 101,325 Nm -2 =
101,325 Pa = 101.325 kPa = 1,013.25 mb = 1.01325 bars
or hectopièze = 14.6959 lbf in -2 = 761.848 mm (29.994 in)
Hg at 16.6°C. Second is Metric * (also ata) equal to
0.98642 Standard * and defined as 0.981117 bars (981.117
mb, ie acceleration due to 1 g) or 14.223 lbf in -2 . Third is
Technical * (at), usually identical with Metric. Fourth is
bar (b), 1000 mb = 750.07 mm Hg = 14.5038 lbf in -2 (see
pressure).
atmospheric absorption Absorption of EM radiation
due to ionisation in atmosphere. Apparent loss of signal
or beam power may be much greater, as result of diffraction
and dispersion by vapour and particular matter.
atmospheric boundary layer Generally defined as
Earth’s surface up to 5,000 ft or 1.5 km.
atmospheric braking Use of air drag, esp. of upper
atmosphere on re-entering spacecraft or RV, converting
very high kinetic energy into heat.
atmospheric circulation Gross quasi-permanent wind
system of Earth, based on bands between parallels of
latitude.
atmospheric constituents See air.
atmospheric diffraction Of importance chiefly with
sound waves, which can be substantially changed in direction
and intensity distribution by changes in air velocity
and density. Effect with most EM radiation is small.
atmospheric duct Almost horizontal layer or channel in
troposphere apparently defined by values of refractive
index within which EM radiation, esp. in microwave
region, is propagated with abnormal efficiency over
abnormally great distances.
atmospheric electric field Intensity of electrostatic field
of Earth varies enormously, but on fine day may be about
100 V m –1 at SL falling to around 5 V m –1 at 10 km height.
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