.  
annunciates HDG SEL as FMA roll mode and illuminates HDG SEL
switch light.

Heading Select Command Mode
The HDG SEL mode commands roll to turn to and maintain heading shown in MCP HEADING display:
.  
initial selection commands turn in shortest direction toward selected
heading bug

.  
after mode engagement, roll commands are given to turn in same
direction as rotation of heading selector

.
bank angle limit is established by bank angle selector

.  
HDG SEL mode automatically disengages upon capture of selected radio
course in VOR LOC and APP modes (VOR/LOC armed).

Approach (APP) Switch
Push –
.
illuminates APP switch light

.
arms the AFDS for localizer and glideslope capture

.
roll mode annunciates VOR/LOC armed

.
pitch mode annunciates G/S armed

.
enables engagement of both autopilots.

APP Mode
The approach mode arms AFDS to capture and track localizer and glideslope and can be engaged for dual or single autopilot operation.
One VHF NAV receiver must be tuned to an ILS frequency before approach mode can be engaged. With one VHF NAV receiver tuned, onside AFDS is enabled for guidance and operation.
For dual autopilot operation, both VHF NAV receivers must be tuned to the ILS frequency and both autopilots must be selected in CMD prior to 800 feet RA. APP mode operation:
. on some airplanes, localizer must be captured prior to glideslope
.
localizer can be intercepted in HDG SEL, LNAV, or CWS R

.
glideslope capture occurs at 2/5 dot below glideslope

.
APP switch light extinguishes after localizer and glideslope capture.

Copyright . The Boeing Company. See title page for details.
4.10.12   December 1, 2000

Automatic Flight -Controls and Indicators 737 Operations Manual
After localizer and glideslope capture, APP mode can be disengaged by:
.  
pushing a TO/GA switch

.  
disengaging autopilot(s) and turning off both F/D switches

.  
retuning the VHF NAV receiver.

.  on some airplanes, during a single autopilot approach, overriding pitch or
roll into CWS.

While engaged in the APP mode:
.  
the A autopilot and Captain’s F/D use information from Captain’s Course
Selector and No. 1 VHF NAV receiver

.  
the B autopilot and First Officer’s F/D use information from First
Officer’s Course Selector and No. 2 VHF NAV receiver

.  
different courses and/or frequencies for the two VHF NAV receivers can
cause disagreement between Captain’s and First Officer’s F/D displays
and affect A/P operation.

Note:  After localizer and glideslope capture during a dual autopilot approach, CWS cannot be engaged by manually overriding pitch and roll. Manual override of autopilots causes autopilot disengagement.
Autopilot / Flight Director

Automatic Flight -Controls and Indicators 737 Operations Manual

Autopilot Engage Paddle:
CMD –
.
engages related A/P

.
enables all command modes

.
displays CMD in A/P status display

.  
selecting a second A/P in CMD disengages the first A/P, unless in APP
mode.

.
enables CWS operation

.
CWS engages if:

.
pitch or roll mode not selected

.
pitch or roll mode deselected

.
pitch or roll mode manually overridden with control column force.

Note:  After localizer and glideslope capture during a dual autopilot approach, CWS cannot be engaged by manually overriding pitch and roll. Manual override of autopilots causes autopilot disengagement.
.
CWS engaged displays:

.
CWS P and/or CWS R in A/P status display

.
blank in pitch and/or roll mode FMA

.  
when approaching a selected altitude in CWS P, the pitch mode engages
in ALT ACQ and ALT HOLD when reaching selected altitude

.  
when approaching a selected radio course in CWS R with VOR/LOC or
approach mode armed, VOR/LOC engages when course is intercepted

.  
if pitch is manually overridden while in ALT HOLD and control force is
released within 250 feet of selected altitude, A/P pitch mode engages in
ALT ACQ and return to selected altitude in ALT HOLD mode.

Note:  During F/D only operation while pitch or roll commands are more than 1/2 scale from center, selecting CMD A or B engages the A/P in CWS for pitch and/or roll and the related F/D bar(s) retract.
　
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