Textron Cessna 172R, Pilot Operating Handbook

Page: 485 / 500

CESSNA
MODEL
172R
SECTION 9
-
SUPPLEMENTS
SUPPLEMENT 20
-
FAA APPROVED
1. MARKER BEACON ANNUNCIATOR LIGHTS - The three-light marker
beacon receiver built into the KMA 28 gives a visual and aural signal
when
the
ship's antenna
passes over a
75
MHz beacon. The blue,
amber, and white lights on the faceplate, as well
as
the audio tones,
identify the beacon type.
OUTER [O] - Light
illuminates blue
to
indicate passage of
outer
marker
beacon.
MIDDLE [M]
-
Light illuminates amber
to
indicate passage of middle
marker beacon.
INNER, AIRWAY and FAN [I]
-
Light illuminates white to
indicate
passage of ILS
inner, airway or fan marker beacons.
2.
MARKER BEACON SENSITIVITY
& TEST/MUTE SELECT SWITCH
-
The three-position switch is used
to
set
the receiver sensitivity and
to
test
the annunciator lamps. When this switch is on "HI" (upper)
position, the high sensitivity is selected which permits you
to
hear
the
outer
marker
tone
about a mile
out.
At this point you may select the
°L0‘ (middle) position
to
give you a more
accurate
location of the
Marker. When used only for approach markers,
many pilots choose to
leave the switch in the LO sensitivity position. The "T/M" (bottom)
position is a momentary switch that will illuminate all three lamps
simultaneously to
assure
they are in working order. This switch also
has
a
Marker Beacon "mute"
function. Pushing the switch
to
the T/M
position while receiving
a
marker
beacon signal will
cause
the audio to
be temporarily silenced. No action is required to restore the
audio in
time for the
next
beacon.
Figure
1
. Bendix/King KMA
28
Audio Selector Panel (Sheet 1 of 5)
Dec 30/00 S20-5
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