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The navigation database includes most data found on navigation charts. This data
can be displayed on the CDU or ND. The database contains:
• location of VHF navigation aids
• airports
• runways
• other airline selected data, such as SIDs, STARs, approaches, and
company routes
• transition altitudes
The FMC contains two sets of navigation data, each valid for 28 days. Each set
corresponds to the navigation chart revision cycle. The FMC uses the active data
for navigation calculations. The contents of the navigation database are
periodically updated and transferred to the FMC before the expiration date of the
active data.
Thrust Management
The thrust management function operates the autothrottle in response to flight
crew mode control panel inputs or to FMC commands. Reference thrust limits can
be selected on the THRUST LIM page. FMC autothrottle commands are made
while VNAV is engaged. Thrust management:
• calculates reference thrust limits and thrust settings, or follows FMC
thrust settings
• commands thrust levers
• senses and transmits autothrottle failures
• commands thrust equalization through the engine electronic controls
Thrust limits are expressed as N1 limits. Thrust equalization references N1.
December 01, 1999
747 Operations Manual
Copyright © The Boeing Company. See title page for details.
11.32.2 D6-30151-425
Flight Management, Navigation -
Flight Management Computer
Thrust management calculates a reference thrust for the following thrust settings:
With VNAV active, the reference thrust limit changes for the phase of flight.
Thrust settings can be selected on the THRUST LIM page. The reference thrust
limit displays at the top of the EICAS display.
With VNAV active, an engine failure, and flaps fully retracted, the reference thrust
limit changes to CON at VREF + 98. The planned thrust reduction point is
inhibited.
The flight crew can specify the thrust reduction height where the change from
takeoff to climb thrust takes place by making an entry on the CDU TAKEOFF
REF page. This can be an altitude from 400 feet to 9,999 feet or an entry of 5 for
flaps 5.
Reduced Thrust Takeoff
Reduced thrust takeoffs lower EGT and extend engine life.
Derate/Variable Takeoff Rating
Two fixed derates, TO1 and TO2, can be selected on the THRUST LIM page.
With both TO1 and TO2, the thrust setting parameter is considered a limitation for
takeoff; therefore, thrust levers should not be advanced further except in an
emergency. A further thrust increase following an engine failure could result in a
loss of directional control. Use the takeoff speeds calculated by the FMC for the
selected derate or variable takeoff rating condition.
Assumed Temperature Thrust Reduction Takeoff
Entering an assumed temperature higher than the actual temperature reduces
takeoff thrust.
Themaximum thrust reduction authorized is 25 percent belowany certified rating.
The assumed temperature thrust setting is not considered a limitation. The
assumed temperature reduction can be removed. If conditions are encountered
where more thrust is necessary, the crew can manually apply full thrust.
• TO–takeoff
• TO 1 – takeoff one
• TO 2 – takeoff two
• D–TO – assumed temperature
takeoff
• D–TO 1 – derate one assumed
temperature takeoff
• D–TO 2 – derate two assumed
temperature takeoff
• CLB–climb
• CLB 1 – climb one
• CLB 2 – climb two
• CRZ–cruise
• CON – continuous
• GA – go–around
April 01, 2001
747 Operations Manual
Flight Management, Navigation -
Flight Management Computer
Copyright © The Boeing Company. See title page for details.
D6-30151-425 11.32.3
Derated Thrust Climb
During climb, CLB 1 and CLB 2 derates are gradually removed. In cruise, the
thrust reference defaults to CLB or CRZ as set by maintenance.
Two fixed climb thrust derates can be selected on the THRUST LIM page. CLB 1
uses a 10% derate of CLB thrust to 10,000 feet, then increases thrust linearly with
altitude to CLB thrust at 15,000 feet. CLB 2 uses a 20% derate of CLB thrust to
10,000 feet, then increases thrust linearly with altitude to CLB thrust at 15,000
feet.
Use of an assumed temperature reduced thrust takeoff or takeoff derate affects
automatic selection of climb derate. For a thrust reduction of up to 5 percent,
maximum climb thrust is selected by the FMC. For takeoff thrust reductions or
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