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BALT SEL: Barometric altitude select.

Band-Pass Filter: 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 plans and the right wing in the lateral plane, positive when the right wing is down.

Barometric Altitude Select: A basic guidance mode, providing vertical guidance to an operator selected barometric altitude.

Barometric Altitude: Height with respect to fixed earth reference (above mean sea level).

Barometric Pressure: Height with respect to fixed earth reference (barometric altitude, feet above mean sea level).

BC: Bus Controller.

Bench Trial: A trial without a jury. The judge rules on facts and evidence presented to him.

Bessel 1841: A standard model for computing earth data.

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

BIS: Built-in simulation

Black Out Dates: Not available. Dates on which tickets or certain fares are not available. Blackout dates usually coincide with holidays and peak travel seasons.

Body Coordinates: Coordinates referenced to the body of the aircraft.

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, known as 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.

BPF: Band-pass filter.

BRG: Bearing.

Bucket Shop: A consolidator; any retail outlet dealing in discounted airfares.

Built-in simulation: 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.

Burden of Proof: The obligation of one party in a suit to prove all the requirements necessary to show entitlement to recovery. If the burden is not met, the party with the burden will lose the issue or the case.

Bus Controller: A term used to define the role of a device on a MIL-STD-1553 bus as being master.