Beechcraft C-12C Operator And Technical Reference Manual page 385

HEADING SWITCH
SELECTION
All on Compass 1
All on Compass 2
Normal
(26) Wind Pointer.
consists of a green symbol located on the outside
edge of the compass and graphically layered to not
obscure the heading bug symbol, lubber line, or
heading readout. The wind indicator rotates about the
aircraft symbol such that the arrow is always pointing
into the compass at the wind direction.
displays zero to five green fins on its tail to represent
wind speed. Long fins represent 10 knots and short
fins represent 5 knots. If the wind velocity is 0 knots,
the arrow is removed from the display. If the wind
velocity is less than 2.5 knots, the arrow is displayed
with no fins. The wind indicator indicates wind from .1
knots to 45.5 knots. If the wind exceeds 45.5 knots,
the wind indicator changes to a maximum wind symbol
(wind indicator with a filled triangle fin at the tail).
When the wind speed or wind direction is invalid or
unavailable, the wind indicator is removed from the
display.
(27) To/From Indicator. A white triangle to or
from indicator rotates around the aircraft symbol on the
course needle. It indicates TO the station when the
triangle points towards the head of the course needle
and FROM the station when the triangle points
towards the tail of the course needle. If FMS is the
selected course and FMS outputs a waypoint alert, the
TO / FROM flag flashes.
If the course source is not FMS, the indicator is
set to TO when the angular difference between the
relative bearing to the station and the primary course
is less than 89q. When the angle is greater than 91q
FROM is indicated. The indicator is OFF when the
angle is between 89q and 91q.
primary source then the FMS determines the TO /
FROM indication. If the TO / FROM indication is
invalid or unavailable, an active navaid has not been
selected, or the indicator is OFF, the TO / FROM flag
will be removed from the display.
(28) Miniature Aircraft.
symbol is located in the center of the compass rose.
Table 3C-7. Heading Reference Indicator Values
ACTIVE FREE / SLAVE
SWITCH
Pilot
Copilot
On-side
The wind indicator
The arrow
When FMS is the
The white aircraft
FREE / SLAVE HEADING REFERENCE
SELECTION INDICATOR DISPLAYED
Free
Slave
Free
Slave
Free
Slave
f. EHSI Operations
(1) OBS Backup Mode. When the heading is
invalid, the compass rose rotates about the aircraft
such that the selected course is always referenced at
the top of the display. When the selected course is
invalid, the compass freezes at the last known
position.
(2) Course
navigation information for the selected course is
flagged invalid, the course source label is removed
from the display and replaced with the course source
annunciation drawn in black on a solid red box. The
deviation bars and scale are removed from the display
with a navigation flag.
invalid, the selected course readout is replaced with
red dashes. If FMS-800 or the KLN 90 is selected and
an FMS NAV Warn occurs (RAIM Alert), the MS NAV
source annunciator turns amber and all the navigation
information remains on the display.
(3) LOC/BC. If an LOC frequency has been
tuned and backcourse is selected on the flight director,
BC is displayed in place of the LOC source. Once BC
has been set it will remain set as long as the BC
discrete is set.
g. HSI ARC Format. The compass arc format,
Figure 3C-11, is a graphic representation of the
current heading of the aircraft.
compass rose, except that only an 80q slice is shown.
The arc format is an expanded compass with the
compass segment at the top of the display and the
aircraft symbol centered laterally at the bottom. The
compass rotates about the center point of the aircraft
such that the current heading is indicated directly
below the lubber line.
The HSI format with the 360q compass rose
display is the same as the HSI Arc display with the
following exceptions.
TM 1-1510-218-10
DG1 (amber)
MAG1 (amber)
DG2 (amber)
MAG2 (amber)
DG (white)
Blank
Source Flag. When
If the primary course goes
It is similar to the
the
3C-31