Electronic Flight Instrument System
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An Electronic Flight Instrument System (EFIS) is a type of electronic display (usually a CRT or LCD) fitted to the cockpit of an aircraft in order to display flight information. EFIS is more efficient in use of space, easier to understand and less costly to maintain than the gauges that traditionally display information in older cockpits.
EFIS-equipped airplanes are frequently referred to as having glass cockpit, a slang reference to the TV-style displays.
In addition to the display units (DU) a complete system will include symbol generators to drive the displays and various data sources including an Attitude and Heading Reference System (AHRS) and air data computer (which may be combined in a single box). There will also be navigation inputs such as GPS, scanning distance measuring equipment (DME), or the Inertial reference system (IRS).
[edit] Components
EFIS is always composed of 2 sets of display: EADI (Electronic Attitude Display Indicator) and EHSI (Electronic Horizontal Status Indicator), or on some airplanes, PFD (Primary Flight Display) and ND (Navigation Display).
On EADI or PFD, most information of the vertical profile such as attitude, Flight Director indication, mode selection, speed indication is indicated.
On EHSI or ND, horizontal flight profile such as Heading, Ground Track, DME and such is indicated.
For redundance and also convenience of pilots, the most critical information relevant to control and safety of the aircraft such as heading and ILS deviation indication during approach is displayed on both indicators.cs:EFIS
