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MAINTENANCE MANUAL
L33470
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MAINTENANCE MANUAL
F. Trajectory Predictions
(1) Trajectory predictions are made for the takeoff, climb, cruise, descent, and approach phases of the flight path. This function also generates three dimensional descent paths. These paths are designed to optimize the time the airplane is in an idle engine configuration while meeting the altitude and speed restrictions of the descent phase.
G. Performance Data Base (PDB)
(1) Data contained in the PDB pertain to airplane drag characteristics. This data is stored in the form of constants and look-up tables. The performances function utilizes this data for calculations and predictions on airplane performance.
H. Reference Parameters
(1) The performance function calculates a variety of reference parameters for display on the CDU and for use by the thrust managment function. These reference parameters consist of maximum altitude and altitude rate, optimum altitude, pitch and roll limits, thrust limits and speed limits.
I. Speed tape display
(1) The speed tape, displayed on the PFD, is a vertical, linear display which moves with respect to a fixed pointer representing the current airspeed. The FMC supplies the following data to the PFD via the EIUs:
(a)
V1, V2 and VR speeds, pilot entered or selected on the TAKEOFF REF page.
(b)
VREF speed, pilot entered or selected on the APPROACH REF page.
(c)
Flaps-up maximum maneuver speed, VM(HI)
(d)
Flaps-up minimum buffet speed, VBF(LO).
(e)
Flap extension and retraction speed schedules VFXR.
J. Performance Factors
(1) The performance prediction calculations may be tailored to specific airplane configuration. This tailoring is accomplished through CDU entry of drag and fuel flow factors on the PERF FACTORS page. The allowable entries are as follows:
(a) Performance (PERF) Code
1) The PERF CODE display, on the CDU PERF FACTORS 1/1 page, is in binary form, and represents the state of the FMC performance option program pins.
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(b)
(c)
(d)
(e)
(f)
(g)
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747-400 MAINTENANCE MANUAL
Drag/Fuel Flow Factors (DRAG/F-F)
1) The drag and fuel flow factor are the corrections to be applied to the airplane drag level and fuel flow model, respectively, stored in the data base. Its purpose is to compensate for airplane and engine modifications and changes. The allowable entry range will be -9.9 to +9.9 with a slash preceeding the fuel flow factor entry.
Manuever (MNVR) Margin
1) The maneuver margin is used for limiting speed targets and advisory altitude displays. The allowable entry range for manuever margin is 1.15 to 1.60.
Minimum Cruise (MIN CRZ) Time
1) The minimum cruise (MIN CRZ) time (in minutes) is used to calculate TRIP altitude for short range operation. The value is used to approximate the minimum fuel profile, and has an allowable entry range of 1 to 20 minutes.
Minimum Rate of Climb (R/C), Climb (CLB)
1) The minimum rate-of-climb (R/C), climb (CLB) values are used in the determination of the minimum rate of climb margin, for flight envelope calculations at climb speed. Maximum altitudes are calculated such that there remains some excess thrust available, equivalent to the minimum rate of climb values. These values may be different for each thrust level (CLB, CRZ and ENG OUT). Allowable entry range is 0 - 999 feet per minute.
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