34-21-00  STANDBY INSTRUMENTS Back

A. System Function

The standby instruments give the flight crew the secondary (standby) indication of the:
  • Magnetic heading of the aircraft
  • Attitude of the aircraft
  • Position of the aircraft in relations to the runway Instrument Landing System (ILS).

B. System Components (Ref. Fig. 1 and Fig. 2)

The primary components of the system are the:
  • Standby compass (Ref. Fig. 1)
  • Standby Artificial Horizon (AH) (Ref. Fig. 2)

C. System Operation

(1) The standby compass operates independently from all other aircraft systems. It contains a magnetic compass card which shows the aircraft heading in relation to magnetic north.

(2) The standby AH contains a gyroscope. The position of the gyroscope, in relation to the longitudinal axis and the lateral axis of the aircraft gives the:
  • Aircraft roll attitude (the roll)
  • Aircraft pitch attitude (the pitch)
(3) The standby AH also gets ILS glideslope (G/S) and localizer (LOC) deviation signals from the VOR/ILS/marker system (Ref. 34-54-00). These inputs move pointers which show the:
  • Vertical position of the aircraft, in relations to glideslope beam (G/S deviation)
  • Horizontal position of the aircraft, in relation to the runway localizer beam (LOC deviation)

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