I
30
NAVIGATION (NAV ARM and NAV
CPLD) Mode
The NAV mode provides visual ,bank
commands on the Flight Command Indicator
and deviation guidance on the PNI to inter-
cept and track a VOR course or an RNAV
course.
Operation of the NAV mode requires the
pilot to:
1.
Tune to the frequency of the selected
VOR (or VORTAC) station. For RNAV oper-
ation, set in waypoint distance and bearing
from the VORTAC station.
2.
Set the PNI course pointer on the de-
sired course.
3.
Establish a;gle
of
intercept by setting
heading "bu and activate "HDG" mode.
4.
Depress tfe NAV button on the Mode
Controller.
When the "NAV" button on the Mode
Controller is depressed, "NAVIARM" will be
lighted on the Annunciator Panel and the
automatic capture circuit is armed. Heading
select,
if
operatng, is retained until capture
occurs.
The VOR or RNAV "course-capture"
point is variable to prevent overshoot and
depends on angle of intercept and the rate
the course deviation is changing. Upon cap-
ture, a bank command will be displayed on
the FCI; the HDG,
if
on,
wit1 be cancelled and
'NAVICPLD" will be lighted on the Annun-
ciator Panel.
The pilot can manually bank the aircraft
to satisfy the command display which will call
for a rollout to wings level when on course
centerline to track the course. Crosswind
compensation is provided in the "track"
state.
If
the NAV mode is selected with the air-
craft level within 24"of bankand within three
dots
of
course deviation, NAVIARM will be
bypassed and NAVICPLD will engage di-
rectl
\
the Autopilot is engaged, the aircraft
will bank to satisfy the command display and
rollout on course automatically.
Upon station (or waypoint) passage, an
outbound course other than the inbound re-
ciprocal can be selected by resetting the
NAV course arrow on the PNI. This will cause
an immediate V-bar deflection on the FCI di-
recting a turn to the new &me.
The NAV mode is cancelled by depres-
sing the NAV button, or selecting HDG (when
in NAV coupled) or APPR modes, or pushing
FD to
"OFF".
Goin back to HDG while adjust-
ing
OBS
is
desiratle.
NOTE:
Operation
of
the Marker Test function
of
the marker beacon receiver after AP-
PROACH CPLD will reduce the Flight Control
system gains.
If
this should occur, the AP-
PROACH mode should
be
recycled.
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