737 Flight Crew Operations Manual
Automatic Flight -
System Description
Boeing Proprietary. Copyright © Boeing. May be subject to export restrictions under EAR. See title page for details.
D6-27370-866-EGP 4.20.7
• LNAV (engaged) – the AFDS intercepts and tracks the active FMC
route. Either of the following capture criteria must be met:
• on any heading and within 3 NM of the active route segment
• if outside of 3 NM of active route segment, airplane must be on an
intercept course of 90 degrees or less and intercept the route segment
before the active waypoint.
• HDG SEL – the airplane is turning to, or is on the heading selected in
the MCP Heading Display
• VOR/LOC (armed) – AFDS is armed to capture selected VOR or LOC
COURSE
• VOR/LOC (engaged) – AFDS tracks selected VOR course or tracks
selected localizer course along the inbound front course bearing.
Autopilot Control Wheel Steering
CWS Engage Switch Selected
Pushing a CWS engage switch engages the A/P pitch and roll axes in the CWS
mode and displays CWS P and CWS R on the FMAs.
With CWS engaged, the A/P maneuvers the airplane in response to control
pressures applied by either pilot. The control pressure is similar to that required
for manual flight. When control pressure is released, the A/P holds existing
attitude.
If aileron pressure is released with 6 degrees or less bank, the A/P rolls the wings
level and holds existing heading. This heading hold feature with bank less than 6
degrees is inhibited when any of the following conditions exists:
• below 1,500 feet RA with the landing gear down
• after F/D VOR capture with TAS 250 knots or less
• after F/D LOC capture in the APP mode.
Pitch CWS with a CMD Engage Switch Selected
The pitch axis engages in CWS while the roll axis is in CMD when:
• a command pitch mode has not been selected or was deselected
YK981 - YQ456
• A/P pitch has been manually overridden with control column force. The
force required for override is greater than normal CWS control column
force.
• selecting CMD while not following a large deviation in the pitch flight
director command.
CWS P is annunciated on the FMAs while this mode is engaged. Command pitch
modes can then be selected.
When approaching a selected altitude in CWS P with a CMD engage switch
selected, CWS P changes to ALT ACQ. When at the selected altitude, ALT HOLD
engages.
September 15, 2016
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