Automatic horizon

Article By:

Angus, James W. Formerly, Intercontinental Dynamics Corporation, Englewood, New Jersey.

Last reviewed:November 2019

DOI:https://doi.org/10.1036/1097-8542.063400

A device that provides the pilot with symbols representative of the attitude of an aircraft relative to an artificial horizon. In an automatic or artificial horizon a vertical gyro moves a horizon bar relative to a fixed aircraft index. Motion of the bar simulates changes in pitch or roll of the aircraft. As the indicator is viewed, the pilot sees the horizon relative to the aircraft as the horizon would appear if it could be seen through the windscreen (see illustration). The vertical gyro may be contained within the indicator, or it may be remote as part of a flight-director system. The gyro can be air-driven (for low-flying aircraft) or electrically driven. The display has been improved by making the space above the horizon bar blue and the area below either black, brown, or green. The aircraft marker, which was formerly a W-shaped wire, now looks much like an aircraft wing. For extreme pitch up or down, the command for the aircraft control is printed on the display as dive or climb. Improvements resulted in optical displays created electronically to increase the information on the display. Means are also included to continuously correct the gyro for precession errors. See also: Gyroscope

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