Cessna 172P Pilot's Operating Handbook And Flight Manual page 275

PILOT'S
OPERAÎING
HANDBOOK
SUPPLEMENT
12
FOSTER,
AN,EA NAVIGATION
(TYPE
511)
sEciloN
4
NORMAL OPERATION
VOR/LOC
OPERATION
VOR,
NAVIGATION
CIRCUTTS
VERIFICATION TESTS:
1.
See
appropriate Nav/Com supplement.
AREA NAVIGATION OPERATING NOTES
1.
Ioss may
be
experienced enroute.
2.
When
a
waypoint from
one
VORTAC
is
displaoed over
a second
VORTAC, interfereuoe
from the
seoond VORTAC eometimes
causes
erratio
and
unusabte BEARING and RANGE displays on
the F,NAV at low altitude.
3.
The RNAV BEARING readout
(to the
waypoint)
becomes
extremely sensitive aud may
become
unusable
within
t '
L
LIZ
miles
of the waypoint. Thus, the RANGE readout is
the
primary
means of approximating waypoint passage'
4.
Tracking from a waypoint
is
not reoommended since the
pilot
would
have to
fty
a
reciprocal bearing
and
make error oorrections
in
the opposite direotion from
flying
to
a
waypoint.
DIAGNOSTIC FUNCTIONS
All
RNAV
systems
ars
rendered
inoporative under
certain
conditions.
The
RNAV
õ11
provides
a
Flag
mode
and
permits
a
diagnostic interpreta-
tion of why the system is inoperative.
FLAG MODE INDICATIONS:
Six "Bars"
Appear in the
Digital Displays
(2
&
6):
a.
PRESS
VOR/DME button (õ) to determine
if
the
VOR,
radial
signal
is
abeeut,
If
VOR
radial signal is
absent,
bars
wíll
change
to
show
&s
"000"
in the BEARING window (2). (One
possible
cause of
this condition
could
be
that the
NAV receiver
is
channeled
to
a
localizer signal.)
1
õ
30
May
1980