Specifications

SECTION III
MODEL 560 INSTRUMENTATION AND AVIONICS
STANDBY HORIZONTAL SITUATION INDICATOR (HSI)
The standby horizontal situation indicator is a three-inch instrument located on the left side of the
center instrument panel. It provides navigational guidance in case of PFD/flight director failure.
The standby HSI displays compass heading, glideslope and localizer deviation and airplane position
relative to VOR radials. The compass card is graduated in 5-degree increments and a lubber line is fixed at
the fore and aft positions. Azimuth markings are fixed at 45, 135, 225, 270, and 315 degrees on the
compass face. A fixed reference airplane is in the center of the HSI, aligned longitudinally with the lubber
line markings.
The course cursor is set by a knob on the instrument. Once set, the cursor rotates in its set position
with the compass card. The course deviation bar, which forms the inner segment of the course cursor,
rotates with the course cursor.
A blue ADF needle, which displays ADF 1 bearings, rotates around the outer portion of the dial.
A heading (HDG) flag will appear in the instrument when the compass system is OFF, the heading
signal from the directional gyro (DG 1) becomes invalid, primary power to the indicator is lost, or the error
between the displayed heading and the received signal becomes excessive.
The course deviation bar moves laterally in the HSI, in relation to the course cursor. Course deviation
dots in the HSI act as a displacement reference for the course deviation bar. When tracking a VOR, the
outer dot represents 10 degrees, while on an ILS localizer it represents 2-1/2 degrees. White TO-FROM
flags point to or from a station along the VOR radial when operating on a VOR. A red warning flag comes
into view when power is OFF, when NAV information is unreliable, or when signals from the NAV receiver
are not valid. The standby HSI displays only NAV 1 information.
The glideslope deviation pointer is located to the right side of the display. When receiving glideslope
information during an ILS approach, the green deviation pointer will be uncovered by the red VERT warning
flag which will otherwise be in evidence. If an ILS frequency is not tuned and being received, or the ILS
signal is unusable or unreliable, the deviation pointer will be covered by the red warning flag.
Figure 3-14. Standby Horizontal Situation Indicator (HSI)
I 56OMB-01 Configuration AA 3-29