Boeing 747-400 Flight Management System Pilot’s Guide

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Boeing 747-400 Flight Management System Pilot’s Guide

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Boeing 747-400 Flight Management System Pilot’s Guide

This Honeywell FMS Pilot’s Guide was written as a training aid to the

operation of the Flight Management System in the B747-400 aircraft.

In no case will this guide be used as an authorized check list or

procedural aid replacing FAA or other certifying authority approved

flight manuals or check lists. Contact Honeywell Flight Operations

Programs Pilots at 602-436-1446 with any aircrew related questions,

problems, or comments.

Pilots using the avionics system described in this document are

required to maintain Lateral and Vertical Situational Awareness at all

times through the use of current and approved en route, sectional,

and other topographical and navigational charts. The avionics system

herein described is designed to aid pilots in enhancing navigational

precision. However, pilots are advised to use all flight following

techniques normally employed, to insure that a valid mental picture

of the topography and desired route is maintained at all times.

Helping You Control Your World

C28-3641-21-01

December 1996

Printed in U.S.A.

©1996 Honeywell Inc.

Rev 1 12/96

PROPRIETARY NOTICE

This document and the information disclosed herein are proprietary

data of Honeywell Inc. Neither this document nor the information

contained herein shall be reproduced, used, or disclosed to others

without the written authorization of Honeywell Inc., except for training

on recipient's equipment.

NOTICE – FREEDOM OF INFORMATION ACT (5 USC 552) AND

DISCLOSURE OF CONFIDENTIAL INFORMATION GENERALLY

(18 USC 1905)

This document is being furnished in confidence by Honeywell Inc.

The information disclosed herein falls within excemption (b)(4) of 5

USC 552 and the prohibitions of 18 USC 1905.

Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

B747-400 FMS PILOT’S GUIDE LR-i

List of Revised Pages

PAGE NO. REV STATUS

Title Page Rev 1 12/96

Proprietary Notice

— 3/94

Table of Contents

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FMS PILOT’S GUIDE

i

Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

PAGE

1 PILOT OVERVIEW .......................................................1-1

2 FLIGHT MANAGEMENT ...............................................2-1/2

2.1 GENERAL OVERVIEW ..........................................2-1/2

2.2 FLIGHT DECK CONFIGURATION ........................2-5

2.3 SYSTEM INTERFACES .........................................2-7

2.4 FLIGHT PHASES ...................................................2-8

2.5 OPERATION ..........................................................2-11

2.5.1 Dual Mode ...................................................2-11

2.6 FUNCTIONS ..........................................................2-13

2.6.1 Navigation....................................................2-13

2.6.2 Performance ................................................2-16

2.6.3 Guidance .....................................................2-17

2.6.4 Thrust Management ....................................2-19

2.6.5 Flight Displays .............................................2-20

2.7 SOFTWARE AND DATA BASE ............................2-22

2.8 MULTIPURPOSE CONTROL DISPLAY UNIT ......2-24

2.8.1 Display Functional Areas ...........................2-26

2.8.1.1 Display ..........................................2-26

2.8.1.2 Lines Select Keys (LSK) ............... 2-27

2.8.1.3 Brightness (BRT) Control .............2-27

2.8.1.4 Annunciators .................................2-27

2.8.2 Alpha Numeric Keys ....................................2-28

2.8.2.1 Slash Key......................................2-28

2.8.2.2 Space Key ....................................2-28

2.8.2.3 Plus/Minus Key .............................2-29

TABLE OF CONTENTS

ii

Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

B747-400 FMS PILOT’S GUIDE 2.8.3 Function Keys ............................................2-29

2.8.4 Mode Keys ................................................. 2-31

2.8.5 Page Formats and Data Labels .................2-33

2.8.6 Data Entry ..................................................2-36

2.8.6.1 Button Push Processing ............... 2-36

2.8.7 Navigational Display (ND) Symbology .......2-37

2.8.8 Initial Power-up Operation .........................2-40

2.8.9 Flight Management System Terminology ..2-40

3 FLIGHT OPERATIONS .................................................3-1

3.1 FLIGHT DATA .......................................................3.1-1

3.2 PREFLIGHT ..........................................................3.2-1

3.2.1 Aircraft Identification .................................. 3.2-2

3.2.2 INIT/REF INDEX........................................3.2-6

3.2.3 Position Initialization ..................................3.2-8

3.2.4 Position Reference ....................................3.2-14

3.2.5 Flight Plan Route Entry.............................. 3.2-16

3.2.6 Departure Selection ...................................3.2-24

3.2.6.1 SID and Departure Runway Entry 3.2-26

3.2.7 Route Discontinuity ....................................3.2-29

3.2.8 Flight Plan Route Activation ......................3.2-32

3.2.9 Performance Initialization ..........................3.2-34

3.2.10 Thrust Limit Data .......................................3.2-40

3.2.10.1 Thrust Lim Page – Airborne ...... 3.2-43

3.2.11 Takeoff Data Entry ....................................3.2-44

3.3 TAKEOFF/CLIMB ..................................................3.3-1

3.3.1 Autothrottle Takeoff ...................................3.3-1

3.3.2 Climb Phase .............................................. 3.3-2

3.3.3 CLB Page ..................................................3.3-2

3.3.4 Climb Profile ..............................................3.3-8

3.3.5 Climb Performance Change ......................3.3-9

3.3.6 RTE LEGS Pages ..................................... 3.3-10

3.3.6.1 RTE DATA ....................................3.3-11

3.3.6.2 Climb Airspeed/Altitude

3.3.6.2 Constraints....................................3.3-16

3.3.6.3 Rules for Airspeed/Altitude

3.3.6.3 Constraints....................................3.3-18

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B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

3.4 CRUISE .................................................................3.4-1

3.4.1 CRZ Page ..................................................3.4-1

3.4.1.1 Route Copy ...................................3.4-5

3.4.1.2 Abeam Points ...............................3.4-7

3.4.1.3 Direct-To/Intercept Course ...........3.4-12

3.4.2 PROGRESS Page .....................................3.4-17

3.4.3 Altitude Step Points ...................................3.4-23

3.4.3.1 Optimum Steps .............................3.4-23

3.4.3.2 Planned Steps ..............................3.4-24

3.4.4 Lateral Offset Route ..................................3.4-26

3.4.5 Holding Patterns ........................................3.4-28

3.4.5.1 RTE 1 LEGS – HOLD AT – Page .3.4-28

3.4.5.2 MOD RTE 1 HOLD Page ..............3.4-29

3.4.5.3 ACT RTE 1 HOLD ........................3.4-34

3.4.5.4 Holding Pattern Guidance ............3.4-35

3.4.6 FIX INFO Page ..........................................3.4-37

3.4.7 REF NAV DATA Page ...............................3.4-41

3.4.8 SELECT DESIRED WPT ..........................3.4-46

3.4.9 DESCENT FORECASTS ..........................3.4-49

3.4.10 Altitude Intervention ...................................3.4-51

3.4.10.1 Cruise Altitude Modification ........3.4-51

3.5 DESCENT .............................................................3.5-1

3.5.1 DES Page ..................................................3.5-2

3.5.2 OFFPATH DES Page ................................3.5-7

3.5.3 ARRIVALS Page .......................................3.5-10

3.5.3.1 VFR Approach ..............................3.5-15

3.5.3.2 Runway Extension ........................3.5-16

3.5.4 Descent Profile ..........................................3.5-17

3.5.5 Altitude Intervention ...................................3.5-18

3.5.5.1 Constraint Deletion .......................3.5-18

3.5.5.2 Altitude Level Off/Resumption ......3.5-18

3.6 APPROACH ..........................................................3.6-1

3.6.1 APPROACH REF Page .............................3.6-1

3.6.2 Radio Tuning .............................................3.6-3

3.6.3 NAV RADIO Page ..................................... 3.6-3

3.6.4 Autotuning .................................................3.6-8

3.6.4.1 DME/DME .....................................3.6-8

3.6.4.2 VOR/DME .....................................3.6-8

3.6.4.3 ILS/MLS ........................................3.6-9

Rev 1 12/96

iv

Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

B747-400 FMS PILOT’S GUIDE 4 ADVANCED FLIGHT PLANNING .................................4-1

4.1 PILOT-DEFINED WAYPOINTS .............................4-1

4.1.1 PBD/PBD and PB/PB ................................4-1

4.1.2 Along Track ...............................................4-2

4.1.3 Latitude/Longitude .....................................4-2

4.1.4 Airway Crossing Fixes ...............................4-3

4.1.5 Summary of Pilot Waypoint Construction ..4-3

4.2 CONDITIONAL WAYPOINTS ................................ 4-4

4.3 FMC ABBREVIATIONS ..........................................4-6

4.4 POLAR OPERATION .............................................4-8

4.4.1 Magnetic/True Reference ..........................4-8

4.4.2 Polar IRS Navigation .................................4-8

4.5 HOLDING PATTERNS .......................................... 4-10

4.5.1 Types of Holding Patterns .........................4-10

4.5.2 Creation and Modification of

Holding Patterns ........................................4-11

4.5.3 EFIS Display of Holding Patterns ..............4-12

4.5.4 Calculation of Holding Pattern Size ...........4-13

4.5.5 Deceleration Segments .............................4-14

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4.5.6 Holding Pattern Entry Types...................... 4-14

4.5.7 Holding Pattern Guidance in Climb ...........4-15

4.5.8 Holding Pattern Guidance in Cruise ..........4-15

4.5.9 Holding Pattern Guidance in Descent .......4-16

4.6 FMC FLIGHT PLAN WIND USAGE ......................4-17

4.6.1 Entry and Propagation of Forecast Winds 4-17

4.6.2 Effect of Flight Plan Modifications on

Wind Propagation ......................................4-20

4.6.3 Mixing of Measured Winds with FMC

Propagated/Forecast Winds ......................4-22

4.6.4 Step Climbs ...............................................4-23

4.6.5 Using the Step Climb Feature to

Evaluate Wind Trade .................................4-24

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B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

5 BACKUP FUNCTIONS ................................................. 5-1

5.1 EFIS CONTROL PANEL .......................................5-1

5.1.1 EFIS CONTROL Page ..............................5-2

5.1.2 EFIS OPTIONS Page ................................ 5-5

5.2 EICAS CONTROL PANEL ....................................5-7

5.2.1 EICAS MODES Page ................................5-7

5.2.2 EICAS SYNOPTICS Page.........................5-8

5.3 STANDBY NAVIGATION ......................................5-10

5.3.1 IRS LEGS Page.........................................5-11

5.3.2 IRS PROGRESS Page ..............................5-12

5.3.3 ALTN NAV RADIO Page ...........................5-15

6 FMS-MCDU MESSAGES ..............................................6-1

6.1 MCDU ALERTING MESSAGES ...........................6-2

6.2 MCDU MESSAGES...............................................6-4

7 ADDITIONAL INFORMATION ......................................7-1

7.1 COST INDEX ........................................................ 7-1

7.2 MAINTENANCE PAGES ....................................... 7-3

7.2.1 MAINTENANCE INDEX Page ...................7-3

7.2.1.1

7.2.1.2 PERF FACTORS ..........................7-5

7.2.1.3 IRS MONITOR .............................. 7-9

APPENDICES

APPENDIX A Index ..............................................................A-1

APPENDIX B Abbreviations & Acronyms.............................B-1

APPENDIX C List of Illustrations..........................................C-1

tHIS PAGE WAS INTENTIONALLY LEFT BLANK.

Section 1 PILOT OVERVIEW

The Honeywell B747-400 Flight Management System (FMS) Pilot

Guide is oriented to the operation of the Honeywell Flight Management

System installed on the B747-400 aircraft.

This automated system integrates sensors, systems, and displays to

provide economy with a minimum workload. The Flight Management

System (FMS) offers the pilot substantial assistance in devising the

flight plan. The FMS software was developed by Honeywell to meet

the unique systems design specifications of Boeing. While optimizing

the flight plan for winds and operating costs, it fills in the details,

suggesting the most economical climb profile, cruise altitude, airspeed,

step climb, and desecent. If the pilot elects the automatic flight mode,

the Flight Management System (FMS) guides the aircraft throughout

the entire flight plan, from takeoff through landing. Additionally, the

FMS attempts to provide the lowest possible cost for the flight while

attempting to satisfy all operational constraints that are imposed on

it. The key roles of the system are performance and arrival predictions.

While fuel consumption is a major component of cost, other factors

are taken into account. These include flight and ground crew wages,

costs of late arrival and other factors determined by the operator.

Thus, a Cost Index (CI) is determined by the operator and the Flight

Management Computer (FMC) uses this Cost Index to develop an

optimized flight.

The Honeywell Flight Management functions include: navigation,

performance and optimization, flight planning management, managed

guidance computation, and information display management.

1-1

Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

1 PILOT OVERVIEW

1-2

Use or disclosure of the information on this page is subject to the restrictions on title page of this document.

B747-400 FMS PILOT’S GUIDE This guide is organized to:

1. Provide a general Flight Management Computer System

(FMCS) overview.

2. Step through FMS operation as it could be used in

airline operations.

3. Provide in-depth information about system functions.

Several appendices provide reference information useful in

understanding this guide.

The Pilot’s Guide is written to provide the information necessary to

operate the Flight Management System (FMS) in most operational

modes. Used with a training device, the pilot gains sufficient knowledge

for in-flight use of the system. The guide contains details sufficient to

answer the majority of questions generated through system use.

The reader should know that every effort has been made to ensure

the accuracy of published information. Questions about current

system operation and configurations should be directed to Honeywell

B747-400 Engineering or the Honeywell Technical Pilots.

This manual is intended as a guide and does not supersede Boeing,

any certifying authority, or any airline approved procedures. It is

written for system familiarization only.

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Section 2 FLIGHT MANAGEMENT

2.1 GENERAL OVER OVERVIEW VIEW The Flight Management System (FMS) provides a means via the

Mode Control Panel (MCP) on the glareshield and the Multipurpose

Control Display Unit (MCDUs) for the pilot to enter a flight plan, select

various flight control modes, and enter other necessary flight data.

Flight progress is monitored through the Multipurpose Control Display

Unit (MCDU) and the Electronic Instrument System (EIS).

After data entry, the Flight Management Computer System (FMCS)

aids the pilot by reducing the workload in flight planning, navigation,

performance management, aircraft guidance, and monitoring of the

flight progress to ensure optimum efficiency and effectiveness (see

Figure 2-1).

Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

2-1/2

2 FLIGHT MANAGEMENT

B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

G3641-21-024#

2-3

Figure 2-1

Flight Management Purpose

G3641-21-024#

THE FLIGHT PLAN ROUTE IS ENTERED AND

FUEL PLANNING DATA IS COMPUTED.

CAPTURES AND TRACKS THE

ASSIGNED FLIGHT PLAN ROUTE.

COMMANDS SPEED AND THRUST

FOR OPTIMUM FUEL ECONOMY.

AIRPLANE LEVELS OFF AND CRUISES

AT THE MOST ECONOMICAL SPEED.

OPTIMUM ECONOMY CLIMBING TO

A HIGHER ALTITUDE AS THE CRUISE

PROGRESSES.

PROVIDES CONTINUING GUIDANCE

ALONG THE FLIGHT PLAN ROUTE,

INCLUDING GREAT CIRCLE ’’DIRECT""

ROUTES.

CONTINUOUS EVALUATION AND

PREDICTION OF FUEL CONSUMPTION

ALONG WITH RECLEARANCE DATA.

AN ACCURATE TOP OF DESCENT POINT

FOR A CABIN REPRESSURIZATION

AND A COST EFFICIENT DESCENT.

FUEL-SAVING IDLE THRUST DESCENT

TO THE DESTINATION AIRPORT.

AUTOMATICALLY COMPLIES WITH

SPEED AND ALTITUDE RESTRICTIONS.

PROVIDES THE TRANSITION TO

THE AUTOMATIC LANDING SYSTEM.

AIRCRAFT DELIVERED AT PROPER

APPROACH SPEED.

THE PILOT IS ADVISED OF THE

PROPER LANDING SPEED.

NAVIGATION INFORMATION IS

DISPLAYED ON THE MOVING MAP

DISPLAY.

B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

2-4

After data entry, the FMCS generates the optimum flight profile from

origin to the destination airport. The system provides automatic

aircraft guidance along the defined path while computing and displaying

current and predicted progress along the flight plan (see Figure 2-2).

ORIG

ARPT

DEPARTURE

PROCEDURES

(RWY, SID, TRANS)

ENROUTE

ARRIVAL

PROCEDURES

(APPR, STAR, TRANS)

MISSED

APPROACH

PROCEDURES

DEST

ARPT

LATERAL FLIGHT PLAN

STEP FL

CRZ FL

STEP CLB

SPEED LIMIT

DECELERATE

GLIDESLOPE

ACCEL

ALT

CONSTR

(AT)

RWY

ACCEL

ALT

SPD CONSTR

THR RED

RWY

ALT

TAKEOFF

CLIMB CRUISE

DESCENT

APPROACH

GO AROUND

THR

RED

G3641-21-001#

T/C

T/D

WAYPOINT

ALT CONSTR

(AT OR BELOW)

VERTICAL FLIGHT PLAN

Figure 2-2

Flight Management System Profiles

To perform these functions, the FMS automatically tunes the navigation

radios and sets courses. The courses are not constrained to navaid

radials. The system provides automated enroute and terminal area

guidance along defined procedures including Standard Instrument

Departures (SIDs), Standard Terminal Arrival Routes (STARs),

holding patterns, and procedure turns. It also provides guidance to a

vertical path, which honors defined altitude and speed, and can fly

lateral offsets to the defined path. In addition, the FMS computes

predicted arrival times and fuel consumption along the flight plan

route and to the flight’s destination.

B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

2-5

2.2 FLIGHT DECK CONFIGURA CONFIGURATION TION The Flight Management System (FMS) consists of two Flight

Management Computers (FMCs),which are installed in the avionics

compartment and two Multipurpose Control Display Units (MCDUs),

also referred to as a CDU, installed in the left and right sides of the

forward pedestal. A third CDU not related to the FMS is installed in the

aft pedestal. Refer to Figures 2-3 and 2-4.

Figure 2-3

Flight Deck Configuration

B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

2-6

Figure 2-4

Flight Deck Layout

B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

2-7

2.3 S SYSTEM YSTEM INTERF INTERFACES ACES Both Flight Management Computers (FMCs) are highly integrated

with other aircraft avionics for both input and output data. The Flight

Management System (FMS) interfaces with the Autopilot Flight

Director System (AFDS) through the Mode Control Panel (MCP) and

Flight Control Computers (FCCs). The left and right FMCs compute

independently; however, they “cross talk” with each other.

The FMC integrates information from air data, inertial reference,

radio navigation, engine and fuel sensors, optional weight and

balance system, an internal navigation data base, and crew-entered

data. Command data for lateral and vertical guidance is supplied to

the Flight Control Computer (FCC) and thrust commands to the

autothrottle servo for automatic guidance.

These multiple sources of information, from which the FMS receives

information, are illustrated in Figure 2-5. Correct aircraft, engine and

data base configuration may be confirmed on the Control Display Unit

(CDU) Identification (IDENT) page on aircraft power-up.

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PILOT

FMC

G3641-21-002#

INTEGRATED

DISPLAY

SYSTEM

(ND & PFD)

CENTRAL

MAINTENANCE

COMPUTER

ELETRONIC

ENGINE

CONTROLS

INERTIAL

REFERENCE

SYSTEM

DIGITAL

CLOCK

AUTOPILOT

FLIGHT

DIRECTOR

SYSTEM

MODE

CONTROL

PANEL

DATABASE

LOADER

ILS/

MLS

VOR DME ADF

OFFSIDE

FMC

WEIGHT

AND

BALANCE

COMPUTER

FUEL

QUANTITY

INDICATING

SYSTEM

AIR DATA

COMPUTER

FLIGHT

CONTROL

COMPUTER

ELECTRONIC

INTERFACE

UNIT

AUTO-

THROTTLE

SERVO

MCDU

Figure 2-5

Flight Management System Interface

B747-400 FMS PILOT’S GUIDE Use or disclosure of the information on this page is subject to the restrictions on the title page of this document.

2-8

2.4 FLIGHT PHASES Figure 2-6 illustrates a typical Flight Management System (FMS)

profile from the preflight phase at origin airport, to the rollout phase

at the destination airport. In addition to Vertical Navigation (VNAV)

guidance and Performance (PERF) modes, the FMS supplies Lateral

Navigation (LNAV) guidance to follow waypoints along the predefined route.

SPEED LIMIT

ALTITUDE

CONSTRAINT

ACCELERATION

ALTITUDE

THRUST

REDUCTION

ALTITUDE

STEP

CLIMB

EARLY

DESCENT

TOP OF CLIMB

INITIAL CRUISE

FLIGHT LEVEL TOP OF DESCENT

SPEED LIMIT

ALTITUDE

CONSTRAINT

FLAPS

EXTENDED

DESTINATION

ORIGIN

PREFLIGHT

PHASE

TAKEOFF

PHASE

APPROACH

PHASE

CLIMB

PHASE

CRUISE

PHASE

DESCENT

PHASE

G3641-21-003#

LATE DESCENT

Figure 2-6

Typical Flight Management System Profile

The pre-defined route may be divided into a number of FMS declared

flight phases to include PREFLIGHT, TAKEOFF/CLIMB, CRUISE,

DESCENT, AND APPROACH.

PREFLIGHT – In this phase the FMS is initialized. A flight plan may

be either recalled from the navigation data base by company route

designator or departure/destination ICAO code identifier, or entered

waypoint by waypoint (strung) on the ROUTE (RTE) page, or

uplinked via Aircraft Communications Addressing and Reporting

System (ACARS).

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2-9

During the preflight phase the following events are accomplished:

• Check of airplane and engine models in the Performance Data

Base, and a check for an active Navigational Data Base.

• Inertial Reference System (IRS) alignment.

• Entry of origin, destination, cruise altitude, flight number, and

cost index.

• Entry of fuel data and zero fuel weight.

• Entry of flight plan route, runway, Standard Instrument Departures

(SIDs), transition and waypoint, revisions to include speed and

altitude.

• Selection of economy or pilot-entered flight phase speeds.

• Confirmation or entry of takeoff “V” speeds.

• Entry of thrust reduction/acceleration altitudes, assumed

temperature for derated thrust performance, and engine out

acceleration altitude.

• Confirm auto tuning of navigation radios for departure

TAKEOFF – This phase extends from initial thrust application to the

thrust reduction altitude where takeoff thrust is normally reduced to

climb thrust. Lateral Navigation (LNAV) and Vertical Navigation

(VNAV) are normally armed before takeoff. The LNAV engages if the

airplane is above 50 feet, and within 2.5 nautical miles of the active

route leg. The VNAV engages above 400 feet with the Performance

Initialization (PERF INIT) page complete. The thrust reduction under

these conditions are automatic at the thrust reduction altitude.

CLIMB – This phase extends from the thrust reduction altitude to

the Top-of-Climb (T/C). The T/C being the point where the aircraft

reaches the cruise altitude entered on the Performance Initialization

(PERF INIT) page. The Vertical Navigation (VNAV) and Performance

(PERF) modes provide guidance for accelerating the aircraft when

above the speed transition and speed restriction altitude. The modes

observe airspeed and altitude constraints that are stored in the

navigational data base or inserted by the pilot.

Rev 1 12/96

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2-10

CRUISE – This phase extends from the T/C to the Top-of-Descent

(T/D). Cruise could include step climbs as well as en route descents.

The Flight Management Computer (FMC) calculates the optimum

step climb point. A step climb requires setting a new altitude target on

the Mode Control Panel (MCP) and initiating a climb thrust pilot

selection. En route descents are initiated by setting a new altitude

target on the MCP and reinserting a new Cruise Altitude (CRZ ALT)

into the Control Display Unit (CDU).

DESCENT and APPROACH – These phases start from the T/D, or

by the pilot initiating a descent via Flight Level Change (FLCH), or via

Vertical Speed (VS). The FMC calculates the appropriate point for the

start of descent and initiates the descent automatically if the Mode

Control Panel (MCP) altitude has been lowered and VNAV and LNAV

are engaged. VNAV guidance can be used to transition onto the ILS

approach, or to fly an entire non-precision approach. If a missed

approach becomes necessary, LNAV and VNAV modes may again

be engaged, in order to automatically fly the Missed Approach

Procedure (MAP).

After landing and engine shutdown, the FMC goes through a “flightcomplete phase”, clearing the active flight plan in preparation for

reinitializing. In addition, some of the data entry fields reinitialize to

default data values.

Rev 1 12/96

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2-11

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2.5 OPERA OPERATION TION The Flight Management System (FMS) provides LNAV, VNAV, and

Performance (PERF) speed control functions to the Autopilot Flight

Director System (AFDS) through targets or steering commands to

the Flight Control Computers (FCCs).

Flight Management Computer (FMC) generated data, commands,

data base information, performance data, and stored information

(routes, waypoints runways, and navaids) are displayed on the

Multipurpose Control Display Unit (MCDU). Each flight mode has its

own page(s). Other available functions are aircraft status

(identification), initialization, radio navigation (radio tuning),

performance (takeoff, climb, cruise, descent, approach, go-around

and climb/approach), data (position monitor), progress, fuel prediction,

route data, route, and standby navigation.

The FMS is operable when electrical power is applied to the aircraft.

Both FMCs monitor power supply levels to detect supply transients

if either short or long duration interrupt FMC operation, but result in

the retrieval of enough previously stored data to recover completely

without affecting FMS operations.

2.5.1 Dual Mode The FMS supports dual, single, and standby operational modes. Dual

mode is the normal operating state of the FMS.

When operating in dual mode, both FMCs independently process

pilot entries on both Multipurpose Control Display Units (MCDUs).

Each FMC makes its own computation and exchanges the various

processed data through cross talk buses for the purpose of comparison

and validation to ensure the information is consistent between FMCs.

If a discrepancy occurs in this exchange of information, a

resynchronization process is automatically initiated to regain consistency between the FMCs. The Built-In Test Equipment (BITE)

function records the cause of any resynchronization or other error for

later analysis. This BITE information/status is not accessible by the pilot.

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The FMC Master Selector switch is use to select the FMC, either left

or right, to provide information to the Flight Control Computer (FCCs),

the Electronic Engine Controls (EECs), and for tuning the VHF

navigational radios.

In the dual Flight Management Computer System (FMCS)

configuration, the left FMC is designated as the Multipurpose Control

Display Unit (MCDU) Button Push Master FMC. This means button

push messages coming from either MCDU are first to be processed

by the left FMC. This means the left FMC decides which button

pushes should be executed and in what sequence to control the

MCDU to FMC communications link. The left FMC in turn sends

button push messages and other information to the right FMC, which

is designated as the slave FMC. Each FMC processes the button

pushes and updates its own MCDU.

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2.6 FUNCTIONS The Flight Management Computer (FMC) part of the Flight

Management System (FMS) performs navigation, performance

computations, and flight planning for the pilot. The guidance

calculations are accomplished using a navigation data base and a

performance data base responding to Multipurpose Control Display

Unit (MCDU) input from the pilot.

2.6.1 Navigation The FMS provides the capability to enter data and complete the

alignment of the Inertial Reference Units (IRUs), compute position,

provide an accuracy level assessment, and provide radio navaid

selection.

Position and velocity information from the IRUs are combined with

range and bearing information from VHF Omni-Range (VOR) and

Distance Measuring Equipment (DME) stations, respectively, to form

an accurate and stable estimate of the aircraft’s position and velocity.

The primary mode of operation is to combine range from two DME

stations (corrected for slant range error), and position and velocity

from the three IRUs. If the aircraft is below 12,500 feet the FMC

autotune is searching for the best DME/DME pair that comes closest

to intersecting the aircraft at an angle between 30° and 150°. Above

12,500 feet, the best pair shall be the pair that comes closest to

intersecting at an angle of 90° with respect to the aircraft position. As

the aircraft progresses along its route, the FMC uses a current

estimate of the aircraft’s position and the stored navaids in the data

base to tune the VOR/DME receivers to the stations that yield the

most accurate estimates of position.

The data base contains information on the class and figure of merit

of the available navaids. The class of a navaid is defined as VOR,

DME, VOR/DME, VORTAC, TACAN, ILS, ILS/DME, LOC DME,

LOC, or MLS. Figure of merit (reception quality) is based on the

usable distance and altitude of the station relative to the aircraft.

These criteria are established by the FAA and other regulatory

authorities.

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The prioritized radio navigational modes for the Flight Management

Computer System (FMCS) to determine its position are:

• IRS/LOC or IRS/MLS (Mode inhibited if RNAV or VOR approach

procedures is in the active flight plan)

• IRS/DME/DME

• IRS/DME/VOR (collocated)

• IRS

The criteria used for FMC selection of navaids for the internal

calculation of a radio-derived aircraft position is illustrated in a typical

example (see Figure 2-7). The example shown indicates that two

frequencies are being tuned by the FMC. They are SY 115.4 and

MSO 115.3. In this case, SY is used for display of the bearing and

distance to the next waypoint; MSO and SY are used for FMC internal

calculation of the aircraft’s present position from VOR/DME data. The

FMC has automatically selected MSO and SY because these stations

meet the figure of merit distance requirement and in addition, they

intercept the aircraft position at an included angle which is closest to

90° compared to other available navaids.

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A336

UPMAN

S32 11.1

E153 17.2

212

o

034

o

S31 23.3 E151 24.6

115.3 MSO

MT. SANDON

S33 56.7 E151 10.3

115.4 SY

SYDNEY

D

G3641-21-004#

100

o

RADIO

POSITION

RADIO

POSITION

Figure 2-7

FMC Navaid Autotune Function

Each FMC independently computes the IRS position as a weighted

average of all three Inertial Reference Units (IRUs). If any latitude or

longitude data from one IRU differs from the previous average by 30

Nautical Miles (NM) or more, that IRU is not used for the remainder of

the flight. An IRS can also be eliminated if the North-South or EastWest velocities differ by more than 20 knots, and if this occurs the IRU

again is eliminated for the remainder of the flight.

The navigation function also computes true and magnetic track,

vertical flight path angle, drift angle, and magnetic variation.

The FMCs do not update the IRSs at any time, and only use the

average IRS position exclusively for navigation when DME and/or

VOR data is not available. When this occurs, after a short delay, the

IRS NAV ONLY message is displayed on the MCDUs. The relative

FMC position to the IRS positions is maintained until valid radio

updating is again received.

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2.6.2 Performance The Flight Management System (FMS) performance modes optimize

the aircraft’s vertical profile integrated with the lateral profile. This

function includes both flight plan predictions and flight optimization.

To develop an optimum flight path, the FMS determines the most

Economical Climb (ECON CLIMB) and Economical Descent (ECON

DES) speeds, the optimum target Mach for Cruise (CRZ), optimum

flight level, and an optimum top-of-descent from cruise to destination

airport. These predictions are periodically updated as the flight

progresses, incorporating aircraft performance and ground speed.

An economy profile results in an economical climb, cruise, and

descent speed/Mach target which is calculated to obtain the minimum

operating cost per mile traveled en route based on the entered Cost

Index (CI). A CI of Zero is equivalent to Maximum Range Cruise

(MRC) because time related cost is not considered and therefore,

fuel efficiency is the only consideration. A Minimum Time speed/

Mach may be obtained when the CI is set to 9999 (producing

maximum flight envelope speeds).

Pilot-entered speeds, such as speed requests from Air Traffic

Control, may alter the strategy for a flight segment with the entering

of specific speed/Mach targets for Climb (CLB), Cruise (CRZ), and

Descent (DES) phases of flight. These speeds are subject to flight

envelope limits.

The computed speed target value is output to the vertical guidance

function which generates the required pitch commands to maintain

the desired Calibrated Airspeed (CAS) or Mach. The thrust target

value is used by the Thrust Management Function (TMF) for use as

a thrust setting parameter in those control modes for which speed is

controlled through the elevator and as an initial thrust setting parameter

value when in cruise. For the cruise portion of the flight, the optimum

CAS or Mach is computed and thrust commands are sent by the

autothrottle to maintain speed. For descent, a vertical path is computed

based on a defined End-of-Descent (E/D) waypoint. The vertical path

accounts for such parameters as: wind, temperature, number of

operating aircraft engines, engine anti-ice, intermediate waypoint

Rev 1 12/96

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altitude and/or speed constraints and the airspeed restriction below

the speed transition altitude (250 knots below 10,000 feet, FAA

rules). Ideally, an idle thrust optimum airspeed descent profile is

flown. However, airspeed may be varied or thrust added to remain on

the path to accommodate unforeseen wind conditions, or for tracking

the vertical path between altitude constraints.

Without the autothrottle or autopilot engaged, the pilot can manually

fly the optimum speed schedule by referring to the Multipurpose

Control Display Unit (MCDU) and to the airspeed bug on the speed

tape on the Primary Flight Display (PFD).

Performance solutions are generated only when the gross weight,

cost index, target altitude, and a route have been entered into the

FMS. Vertical Navigation (VNAV) can only output valid vertical

guidance if performance initialization is complete.

2.6.3 Guidance The guidance function implemented as part of the Flight Management

System (FMS) provides commands for controlling aircraft roll, pitch,

speed, and engine thrust. Fully automatic, performance-optimized

guidance along flight paths in two or three dimensions are available

in LNAV and VNAV. These modes are coupled to the Flight Director

(FD) and/or the autopilot and autothrottle via the Mode Control Panel

(MCP). LNAV and VNAV may be used separately or together. LNAV

provides lateral guidance, and VNAV provides vertical guidance and

speed/thrust control. Air Traffic Control constraints may be inserted

along the flight plan route, thus allowing path and performance

guidance to the three dimensional profile, when LNAV and VNAV are

flown together.

Lateral Guidance – This function is provided by a primary flight

plan with automatic route leg sequencing and route leg updating. The

LNAV guidance function compares the aircraft’s actual position with

the desired flight path and generates steering commands to the

autopilot and flight director. This causes the aircraft to fly along the

desired path. Direct guidance from the aircraft’s present position to

any waypoint is also available. LNAV can only be engaged when a

route has been activated and executed through the Multipurpose

Control Display Unit (MCDU).

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Vertical Guidance – This function encompasses the takeoff, climb,

cruise, descent, and approach phases of the flight plan. The flight

planning capability of the FMS includes means to enter published

departure, arrival, and approach segments and individual waypoints

that include speed/altitude and time constraints. These constraints,

as well as the entered cruise altitude and cost index, define the

vertical profile for which the FMS provides guidance. The entered

profile may be modified at any time to comply with Air Traffic Control

(ATC) requests.

The outputs of the vertical guidance are pitch commands to the Flight

Control Computers (FCCs) and thrust commands to the autothrottle

servo motor. For unconstrained vertical paths (most climbs), the

Flight Management Computer (FMC) generates pitch commands to

control speed consistent with the performance management mode

selected. The pitch commands are based on the difference between

the actual CAS or Mach and the target CAS or Mach computed by the

performance management function. During intermediate level-offs in

climb, or in cruise, or when tracking the descent path, pitch commands

are generated to maintain the desired path or altitude.

When the speed is controlled on the elevator, (vary the rate of climb

to control speed), the autothrottle is commanded to maintain a target

N1/EPR setting, (for example, climb thrust, hold or idle). However,

when the path is controlled on the elevator, the autothrottle is

commanded to maintain the target CAS, Mach, or idle.

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2.6.4 Thrust Management The thrust management function of the FMC controls the autothrottles.

The autothrottles provide full-time automatic thrust control from start

of takeoff through landing and rollout or go-around.

The system uses the FMCs to directly control the throttles for

maximum fuel conservation without having to send commands to

another computer.

An autothrottle switch, thrust mode switches, and indicators on the

Autopilot Flight Director System (AFDS) Mode Control Panel (MCP)

are used for autothrottle control. The FMC operates the throttle servo

in response to manual mode request selection by the crew from the

MCP, or to automatic mode requests from the FMCs when Vertical

Navigation (VNAV) is engaged.

The FMC computes and displays thrust limits for all modes, and

controls full-throttle operation to provide maximum thrust without

exceeding engine operating limits.

The Thrust Management Function (TMF) calculates a reference

thrust based of existing pressure altitude and ambient temperature

data from the Air Data Computer (ADC) for the following modes:

< TO Takeoff

< TO 1 Takeoff 1

< TO 2 Takeoff 2

< TO B Takeoff Bump

< D-TO Assumed Temperature Takeoff

< CLB Climb

< CLB 1 Climb 1

< CLB 2 Climb 2

< CRZ Cruise

< CON Continuous

< GA Go-Around