737 MAX Flight Crew Operations Manual
Flight Management, Navigation -
Flight Management Computer
11.32.4
MN-FLT-OH-201
Derated Thrust Climb
Two fixed climb thrust derates can be selected on the N1 LIMIT page. CLB–1
provides a climb limit reduced by 3% N1 (approximately 10% thrust). CLB–2
provides a climb limit reduced by 6% N1 (approximately 20% thrust). The
reduced climb setting gradually increases to full rated climb thrust by 15,000 feet.
In cruise, the thrust reference automatically changes to CRZ. The reference can be
manually selected on the N1 LIMIT page.
Use of an assumed temperature reduced thrust takeoff or takeoff derate affects the
FMCs climb derate computation. If a reduced thrust takeoff has been specified on
the TAKEOFF REF page, the FMC will re-compute CLB-1 and CLB-2 values as
required to avoid a climb N1 value greater than the reduced thrust takeoff N1
value.
Use of derated climb thrust reduces engine maintenance costs, but increases total
trip fuel.
Fuel Monitoring
The FMC receives fuel quantity data from the Fuel Quantity Indicating System
(FQIS) or from manual entries on the CDU. The fuel quantity source is selected
on PROGRESS 5/5 page. Selections include a TOTALIZER (6L) and
CALCULATED (6R). TOTALIZER is the default value.
March 1, 2021