737 MAX Flight Crew Operations Manual
Flight Management, Navigation -
FMC Messages
MN-FLT-OH-201
11.60.5
ALERTING MESSAGE
CAUSE
CORRECTIVE ACTION
FMC APP/TUNE
DISAGREE
(U14.0 and above)
An approach that utilizes
FMC generated glide
path is in the active flight
plan but an approach
navaid (ILS/GLS/LPV)
has been tuned with G/S
ON.
Confirm the tuned
frequency and approach
selected in the FMC are
both consistent with the
actual approach intended
to be flown. Resolve
tuning or approach
selection inconsistency.
Clear the message.
FMC DISAGREE
During approach or on
the ground, monitored
parameters required for
dual FMC operation are
in disagreement. (Dual
FMC as installed)
Message will remain
displayed until the
condition has been
resolved. The FMC does
not check for mach and
indicated airspeed
miscompares on the
ground.
Monitor FMCs closely.
Both FMCs remain
online. Limit approaches
to single FMC only. If
desired, revert to
SINGLE FMC
OPERATION in this
section.
FMC DISAGREE -
VERTICAL
A vertical deviation,
FMC Airspeed, or FMC
Mach value
disagreement between
the FMCs by more than
the allowed tolerance
occurs and long enough
that all attempts to
resynchronize failed
while the aircraft in a
path descent. Message
display is inhibited when
in the Approach Nav
environment. (dual FMC
as installed)
Do not move the FMC
source select switch.
Monitor crossing
altitudes to ensure
compliance.
March 1, 2021
