Definition

An Electronic Attitude Direction Indicator (EADI) is a part of the Primary Flight Display (PFD) in glass cockpit aircraft. The EADI performs the functions of a traditional attitude indicator, along with certain guidance functions such as flight director symbology.

Description

In most Electronic Flight Instrument System (EFIS) installations, the EADI appears in the top half of the PFD, between the airspeed and altitude tapes. Like a traditional attitude indicator, the EADI displays pitch and roll, and it also includes a slip/skid indicator for turn coordination. However, an EADI also provides the display for flight director symbols, which give the pilot a visual indication of the aircraft attitude required to follow flight director guidance.

In typical installations, a symbol known as the Flight Path Vector (FPV) shows current flight path in relation to the horizon. In simple terms, when the pilot lines up the FPV with the flight director symbol, the aircraft will follow directional guidance from the flight director. Other symbols on the EADI provide information such as Instrument Landing System (ILS) glide slope deviation and ILS lateral deviation.