Cessna 172R, 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