Cessna 172R, Operating Handbook

Page: 456 / 500

SECTION
9
-
SUPPLEMENTS
SUPPLEMENT
15
-
FAA APPROVED
CESSNA
MODEL 172R
7.
APPROACH (APR) COUPLING:
(To
enable glideslope
coupling on an ILS and more precise tracking on instrument
approaches).
a.
When equipped with DG:
1) BARO
setting
- CHECK (if installed).
2) OBS Knob
--
SELECT desired approach course.
(For
a
localizer,
set
it
to
serve
as
a memory aid.)
3) APR Mode
Selector Button
--
PRESS. Note APRARM
annunciated.
4)
Heading Selector Knob
--
ROTATE BUG
to
agree
with
desired approach.
NOTE
When APR is selected, the autopilot will flash HDG for 5
seconds
to
remind the pilot
to reset
the HDG bug
to
the
approach course.
If
HDG mode was in use
at
the time of
APR button selection, a
45°
intercept angle will
then be
automatically established based on the position
of
the bug.
I
I
NOTE
All angle intercepts
compatible with radar
vectors
may be
accomplished by selecting
ROL mode
PRIOR
to
pressing
the APR button. The HDG bug
must
still be positioned
to
agree with the desired approach course
to
provide course
datum
to
the autopilot when using a DG.
a)
If the CDI needle is
greater
than 2 to 3 dots from
center,
the autopilot will annunciate APRARM; when
the computed
capture
point
is reached
the ARM
annunciator will go
out
and the selected course will
be automatically captured and tracked.
b) If the CDI needle is less than 2
to
3 dots from
center,
the HDG mode will disengage upon selecting APR
mode; the APR annunciator will illuminate and the
capture/track
sequence will
automatically begin.
S15-28 Revision
1