Glossary of Aviation Terminology

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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 altitude select (BALT SEL): A basic guidance mode, providing vertical guidance to an operator selected barometric altitude;

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: The aircraft, usually referring to a coordinate system;

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

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 result in correction factors to be downloaded from the host processor to the device; during boresighting, the device is usually not available; See Also: alignment, calibration, initialization;

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 maintenance crews; Compare: real-time engineering simulation;

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

A , B , C , D , E , F , G , H , I , J - K , L , M , N , O , P , Q - R , S , T , U , V, W, X - Z