OPERATIONS MANUAL

Automatic Flight
MCP:
Lateral navigation switch
Push If LNAV mode is armed:
Disarms LNAV mode.
If LNAV is not armed and not engaged:
Arms LNAV mode.
When armed or engaged, switch light illuminates
and PFDs annunciate LNAV in white (armed) or
green (engaged).
Armed LNAV will automatically engage when all
of the following conditions are true:
+ Aircraft is above 50 ft during takeoff, or above
400 ft in other flight phases.
+ Master FMC is operative.
+ An active route leg exists in FMC.
+ Aircraft is on intercept heading to active leg,
or within 2.5 nm abeam the active leg.
+ Three or four engines are running.
+ IRS is aligned.
+ Pitot/static and TAT probe heat power is
available.
When LNAV is engaged:
AFDS commands roll to follow active FMC
route; or commands roll to maintain last
heading after any of the following events:
• Last waypoint of active route is overflown.
• Last waypoint of route offset is overflown.
• Route discontinuity occurred in active leg.
• Airway intercept modification or inactive
route is activated, and aircraft is not on
intercept heading to, and not within 2.5 nm
abeam the new active leg.
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