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attenuation
attenuation Loss of signal strength of EM radiation, esp.
broadcast through atmosphere, due to geometric spread
of energy through volume increasing as cube of distance,
loss of energy to Earth, water vapour, air and possibly
ionised E and F layers.
attenuation factor Ratio of incident dose or dose rate to
that passing through radiation shield.
ATTG Automated tactical target graphic[s].
AT 3 , AT3, AT- three See ATTT.
Attinello flap Blown flap.
ATTITB Air Transport and Travel Industry Training
Board (UK).
attitude Most, if not all, aircraft * described by relating
to outside reference system three major axes OX/OY/OZ
(see axes); * of flight relates these mutually perpendicular
co-ordinates to relative wind; * with respect to ground
relates axes to local horizontal.
attitude control system, ACS Control system to alter or
maintain desired flight attitude, esp. in satellite or spacecraft
to accomplish this purpose in Earth orbit or other
space trajectory. Typical *** uses sensing system, referred
to Earth’s limb, star or other ‘fixed’ point or line, and
imparts extremely small turning moments to structure by
means of gas jets or small rocket motors. In some cases
passive *** used (PACS), or vehicle stabilized by spin
about an axis, with portions despun if necessary.
attitude gyro Loosely, gyro instrument designed to indicate
attitude of vehicle. Specif., instrument similar to
artifical horizon but with 360° freedom in roll and preferably
360° freedom in pitch. Also applicable to
conventional horizon with restricted indications of movement
in aircraft not intended for aerobatics.
attitude jet 1 Reaction jet imparting control moments to
aircraft at low airspeed (see RCS).
2 Sometimes applied to small thrusters or attitude
motors used for same purpose on spacecraft.
attitude motor Small rocket motor used to control attitude
of space vehicle (see thruster, reaction control engine).
attitude reference symbol Usually an inverted T giving
heading and pitch attitude in HUD symbology.
ATTLA Air transportability test-loading agency (US).
ATTMA Advanced technology [or tactical, or theater]
transport mission analysis.
ATTN Attention.
atto Prefix, ×10 –18 , symbol a; thus, 1 am (attometre) =
0.000000000000000001 m.
attributes Inherent characteristics of a finished part that
determine its capability.
attrition Wastage of hardware in operational service,
esp. of combat or other military aircraft.
attrition buy Additional increment of production run
ordered to make good anticipated attrition over active life
of system.
attrition rate Usually means average [actual or
predicted] loss per year.
attrition ratio Many meanings, none of which compare
losses with those of enemy.
ATTS Air-transportable towed system.
ATTT Advanced tactical targeting technology.
ATTU 1 Atlantic to the Urals (NATO).
2 Advanced Tactics and Training Unit (RAF Valley).
ATU 1 Antenna, or automatic, tuning unit.
2 Aerial [or aircraft] target unit.
ATUA Air Transport User’s Association (UK).
AUEW
ATUC Air Transport Users’ Council [London WC2B
6TE] (UK).
Atugs Armed tactical unattended ground sensor.
ATV 1 Associazione Tecnici di Volo Aviazione Civile
(I).
2 Automated transfer vehicle, also called space tug.
3 Atmospheric test vehicle.
4 Aircrew training vessel (UK MoD).
ATVA Active tuned vibration attenuator, or absorber.
AT-Vasi Abbreviated T-Vasi, ten light units on one side
of runway in single 4-unit wing bar plus 6-unit bisecting
longitudinal line.
ATVC Ascent thrust-vector control.
ATVP Aerospace technology validation programme
(UK).
ATVS Advanced TV seeker.
ATW Advanced tactical workstation.
ATW Wing-on-tail aerodynamic influence coefficient.
ATWGS Advanced tactical weapon guidance system.
A2I2 Accelrated-accuracy improvement initiative
(Navstar/GPS).
ATWS Active tail-warning system.
ATZ Aerodrome traffic zone.
AU, a.u. Astronomical Unit[s].
AU 1 Air University (Maxwell AFB, USAF, founded
15 March 1946).
2 Utility aircraft (USA, USAF, 1956–62).
AUAP Andrews University Air Park [Berrien Springs,
MI 49104–0001] (US).
AUC See ATUC.
audio box, audio control Governs voice communication
and broadcast throughout aircraft and by telephone to
ground crew.
audio frequency Frequency within range normally heard
as sound. Limits vary widely with individuals but
normally accepted 15 Hz to 20 kHz, upper limit being
depressed with advancing age.
audio integration unit Interlinks ‘classic’ cockpit with
TCAS, EGPWS and other newer audio systems.
audiometer Instrument for measuring subject’s ability to
hear speeches and tones at different frequencies.
audio oscillator Multi-valve (tube) or multi-transistor
stage in superheterodyne receiver serving as local oscillator
and amplifier (detector).
audio panel Cockpit panel controlling all communications
systems.
audio speed signal Aural indication of vehicle speed,
either on board or at ground station; usually has pitch
proportional to sensed velocity, indication being qualitative
only (see aural high-speed warning).
audio warning Loud warning by horn, buzzer, bell or
voice tape in headphones or cockpit loudspeaker indicating
potential danger. Examples: incorrect speed
(usually sensed airspeed) for regime, configuration or
other flight condition; potentially dangerous excursion of
angle of attack; ground proximity; incorrect configuration
(gear up, wings at maximum sweep, etc).
Audist Agence Universitaire de Documentation et
d’Information Scientifiques et Techniques (F).
audit Comprehensive detailed examination of aiframe
structure of aircraft in line service, esp. after fatigue problems
encountered on type.
AUEW Amalgamated Union of Engineering Workers
(UK).
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