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OSWEGO - Avionics Dictionary Category: Electronics and Engineering > Avionic terms Date & country: 11/08/2008, USA Words: 560

Above ground level (AGL).
Distance of the aircraft above the ground Synonyms: radar altitude;

Above sea level (ASL).
Distance of the aircraft above mean sea level

Absolute.
A standard, fixed reference, as opposed to moving reference; Compare: relative;

Acceleration east.
Aircraft acceleration in true east direction; Symbols: A sub E; Typical Units: ft/s-squared; Dimensions: Length / Time-squared;

Acceleration north.
Aircraft acceleration in true north direction; Symbols: A sub N; Typical Units: ft/s-squared; Dimensions: Length / Time-squared;

Acceleration.
Rate of change of velocity, either scalar or vector, often with subscripts such as ENU or XYZ to denote the coordinate frame; time derivative of velocity; time integral of jerk; Symbols: a, A; Typical Units: ft/s-squared, g; Dimensions: Length / Time-squared;

Accelerometer.
An inertial device for measuring acceleration, usually in three orthogonal axes (lateral X, longitudinal Y, and vertical Z); accelerometers usually consist of a mass, spring, and damper; accelerometers are usually included in inertial sensors, such as AHRS and INS;

Accept.
To allow to proceed, for example with a position update, usually by an operator; Compare: reject

Accuracy.
Measure of exactness, possibly expressed in percent; Compare: precision

Acquire.
To begin reception of useful data

Activate.
To begin performing a mission objective, such as flying along a radial of a radio station; usually refers to a mode of radio navigation, such flying along that radial after capturing that radial; See Also: capture criterion; Compare: arm, capture;

ADC.
Air data computer

ADDR.
Air data dead reckoning

ADF.
Automatic Direction Finding

Advisory.
A signal to indicate safe or normal configuration, condition of performance, operation of essential equipment, or to attract attention and impart information for routine action purposes (from MIL-STD-1472D); an annunciator that is the least critical (less than a caution or a warning);

AFCS.
Automatic flight control system

AGL.
Above ground level

AGR slant range.
Straight-line distance from the aircraft to a point on the ground;

AGR.
Air-ground ranging

AHOV.
Approach to hover

AHRS.
Attitude Heading Reference System

Aiding.
A process by which one or more sensors provide data to another sensor to produce results better than any single sensor; aiding occurs at the data source level or at the physical device level, depending upon specific implementation of the device and the data source (choice of implementation is transparent above the data source); aiding is automatica...

Aileron.
A control surface on fixed-wing aircraft, usually mounted on the aft edge of wings, that controls roll, and is controlled by the wheel; Symbols: delta sub A; Typical Units: rad, deg;

Air Data Computer (ADC).
A primary navigation data source. A navigation sensor based on atmospheric data sensors; usually measures static pressure, dynamic pressure, and outside air temperature; sometimes computes other atmospheric data, such as indicated airspeed, Mach number, calibrated airspeed As a guidance mode, ADC is least accurate of the listed modes and is used on...

Air data dead reckoning (ADDR).
Dead reckoning navigation based on simple instruments as source (barometric altimeter, magnetic compass, airspeed indicator, known wind conditions); sometimes called dead reckoning;

Air Traffic Control (ATC).
Standard aviation term

Air-ground ranging (AGR).
Straight-line distance from the aircraft to a point on the ground;

Air-mass flight path angle.
Angle in vertical plane of earthspeed vector and groundspeed vector; occasional definition for flight path angle; Compare: earth-referenced flight path angle; Symbols: gamma sub A; Typical Units: rad, deg;

Aircraft (ac).
A craft that flies in the air; either fixed or rotory wing.

Airspeed (as, a/s).
See Also: state data, true airspeed, indicated airspeed, calibrated airspeed; Symbols: V sub A/S; Typical Units: kt, ft/s; Dimensions: Length / Time;

Airy.
A standard model for computing earth data

Alignment.
A basic control to a data source from controls and displays to align a device. Also a procedure to align physical devices, usually navigation sensors, so that they provide the most accurate results possible; commonly required by INS, AHRS, barometric altimeter; See Also: boresighting, calibration, initialization;

Altimeter.
A device to measure altitude, either barometric altitude or radar altitude

ALTINTVAL.
Altitude integral input

Altitude error scale factor (KZSF).
A guidance control law parameter, generated by the vertical guidance modes; varies control authority of vertical guidance

Altitude error.
A basic output from guidance to flight director, indicating the difference between actual altitude and desired altitude; Symbols: DELTA h; Typical Units: ft; Dimensions: Length

Altitude integral gain (KALTINT).
A guidance control law parameter, generated by the vertical guidance modes; varies control authority of the altitude integral in vertical guidance, to reduce steady-state errors in altitude error Typical Units: ft; Dimensions: Length;

Altitude.
Height, usually with respect to the terrain below (radar altitude, feet above closest dirt) or fixed earth reference (barometric altitude, feet above mean sea level); Symbols: h; Typical Units: ft; Dimensions: Length;

Angle of attack.
The difference between pitch and the air-referenced flight path angle; the angle between the aircraft center line and the airspeed vector in the vertical plane, positive when the nose is up; Symbols: alpha; Typical Units: rad, deg;

Angular acceleration.
Rate of change of angular velocity, either scalar or vector, often with subscripts such as XYZ to denote the coordinate frame; time derivative of angular position; time integral of angular acceleration; Symbols: alpha; Typical Units: rad/s-squared; Dimensions: 1/Time-squared;

Angular position.
Amount of rotation about an axis, either scalar or vector, often with subscripts such as XYZ to denote the coordinate frame; time integral of angular velocity; Synonyms: angle; Symbols: theta; Typical Units: rad, deg;

Angular velocity.
Rate of change of rotation about an axis, either scalar or vector, often with subscripts such as XYZ to denote the coordinate frame; time derivative of angular position; time integral of angular acceleration; See Also: tachometer; Symbols: omega; Typical Units: rad/s, rpm; Dimensions: 1/Time;

Annunciator.
Any one of warning, caution, or advisory; Synonyms: alert;

Aperiodic.
A process that executes based on events rather than a fixed rate, it is not synchronized to other processes of interest; Compare: periodic;

APPR.
Approach

Approach (APPR).
To fly towards a point; a basic guidance mode, providing lateral guidance, longitudinal guidance, and vertical guidance to a point at an operator selected groundspeed and radar altitude; See Also: waypoint approach, ILS approach, rendezvous approach;

Approach to hover (AHOV).
Hover approach of a rotary wing aircraft.

Arm.
To strive for a mission objective, such as flying toward a radial of a radio station; usually refers to a mode of radio navigation, such as striving to reach a specific radial of a radio station prior to flying along that radial; See Also: capture criterion; Compare: activate, capture;

ASL.
Above sea level

Astronomical latitude.
Latitude measured with respect to vector of apparent gravity; Compare: geocentric latitude, geodetic latitude; Symbols: Phi sub A; Typical Units: rad, deg,DMS;

ATC.
Air Traffic Control

Atmospheric data.
Environmental data related to the atmosphere at some point of interest

Attitude.
The primary aircraft angles in the state vector; pitch, roll, and yaw;

Australian National.
A standard model for computing earth data

Automatic Direction Finding (ADF).
A basic guidance mode, providing lateral guidance to a radio station. Equipment that determines bearing to a radio station;

Autopilot.
A mode of an automatic flight control system which controls primary flight controls to meet specific mission objectives, such as maintain a heading or altitude; Synonyms: automatic flight control system;

Averaging filter.
A filter for combining multiple data sources, usually of the same type, by adding with weighted averages; a simple average of the data sources; Compare: complementary filter, Kalman filter;

AVM.
Avionics monitor

Axis.
One direction in an orthogonal reference frame;

Azimuth.
An angle in the horizontal plane, usually measured with respect to body coordinates

BALT SEL.
Barometric altitude select

Band-pass filter (BPF).
A filter that allows frequencies between two cutoff frequencies to pass while attenuating frequencies outside the cutoff frequencies; a band-pass filter can be constructed as the composition of a low-pass filter and a high-pass filter;

Bank angle.
The angle between the horizontal plnase and the right wing in the lateral plane, positive when the right wing is down; Synonyms: roll; Symbols: phi,Phi; Typical Units: rad, deg;

Barometric altitude.
Height with respect to fixed earth reference (above mean sea level); Synonyms: pressure altitude; Symbols: h sub b; Typical Units: ft; Dimensions: Length;

Barometric pressure.
Height with respect to fixed earth reference (barometric altitude, feet above mean sea level); Synonyms: pressure; Symbols: p sub a; Typical Units: in HG,mbar; Dimensions: Mass /Time-squared * Length;

BC.
Bus controller

Beacon.
A device, usually based on the ground, that aids in determining position or direction;

Bearing (BRG).
Direction on a compass; Synonyms: direction; Symbols: B; Typical Units: rad, deg;

Bessel 1841.
A standard model for computing earth data

Bias.
An offset applied to a measurement for error correction; Synonyms: offset

BIS.
Built-in simulation

Body coordinates.
Coordinates referenced to the body of the aircraft; See Also: XYZ; Compare: earth coordinates, stability coordinates

Body.
The aircraft, usually referring to a coordinate system;

Boresight angle.
The angle between the center line of a sensor and aircraft center line, either by design or by misalignment;

Boresighting.
A basic control to a data source from controls and displays to boresight a device; Also, a procedure to align the center line of physical devices, usually update sensors, so that they provide the most accurate results possible; a basic control to a data source from controls and displays; commonly required by FLIR, MMR; boresight procedures commonly...

BPF.
Band-pass filter

BRG.
Bearing

Built-in simulation (BIS).
Function in avionics software that simulates sensors, aircraft, and pilot, to exercise avionics software (including navigation, radio navigation, guidance and flight director); BIS is often used by a development team to check basic operation following installation of new software or patches; BIS is seldom used by aircraft flight crews or maintenanc...

Bus controller (BC).
Term defining role of device on a MIL-STD-1553 bus as being master; Compare: remote terminal;

Calibrated airspeed (CAS).
Indicated airspeed corrected for instrumentation errors, but not for air density; See Also: airspeed; Symbols: V sub 'CAS'; Typical Units: kt,ft/s; Dimensions: Length / Time;

Calibration.
A basic control to a data source from controls and displays for calibrating a device; Also, a procedure to adjust physical devices so that they provide the most accurate results possible; calibration procedures commonly result in correction factors to be downloaded from the host processor to the device; during calibration, the device is usually not...

Cant angle.
Angle of nacelle mounting; Typical Units: rad, deg;

Capture criterion.
A test case to determine if an armed objective has been captured; In avionics, an aircraft might have an objective to fly to a radial of a radio station, then to fly along it. While enroute, the objective is armed, meaning that the crew and software are attempting to reach the radial. The radial is captured and the objective is met when the capture...

Capture.
To attain an objective, such as reaching a radial of a radio station; See Also: capture criterion; Compare: activate, arm;

CAS.
Calibrated airspeed

Caution.
A signal which alerts the operator to an impending dangerous condition requiring attention, but not necessarily immediate action (from MIL-STD-1472D); an annunciator that is more critical than an advisory but less critical than a warning;

CCLIM.
Course cut limit

Center line.
Standard aviation term

CEP.
Circular error probability

Channel.
A number that maps to a frequency;

Circular error probability (CEP).
A probability that a percentage of two-dimension measurements will lie within a circle of given radius, with the circle centered at truth or mean of the measurements; Compare: radial error probability, spherical error probability; CEP specifies test cases for measurement errors of sensors of two dimensions, such as velocity east and north.

Clarke 1866.
A standard model for computing earth data

Clarke 1880.
A standard model for computing earth data

Collective cue.
A vertical flight director cue for rotary-wing aircraft, primarily to control altitude, by changing power; Compare: yoke cue; Symbols: Gamma sub 'VERT'; Typical Units: percent,in;

Collective.
A flight control operated by moving up or down with hand in rotary-wing aircraft, primarily to control lift (altitude); controls collective (total) pitch of the rotors on a rotary-wing aircraft;

Commanded.
Controls given to a device, not that the device necessarily obeyed the controls

Communications.
How well equipment is communicating; Values: operational, degraded, failed

Complementary filter.
A filter in which the complement of the filter is desired, giving the effect of a high-pass filter by implementing a low-pass filter; a filter for combining multiple data sources, usually of different types, by adding filtered values, where the sum of the filters in the frequency domain is unity; a Kalman filter with fixed gains; Complementary filt...

Computer cycle.
In a periodic, cyclical computer system, the most basic, fastest timing loop

Continuous time.
Time which can have any point expressed as a real quantity, without regard for any specific interval or processing rate; Compare: discrete time;