Boeing 737 - 600/700/800/900. Operations Manual (1997 year)

Flight Management, Navigation -

Flight Management System

Operation

Boeing 737 Operations Manual

Cruise

Before the top of descent, FMC is in cruise mode and uses VNAV PTH and ECON

cruise speed.

Descent

After top of descent, FMC is in descent mode and VNAV changes to economy

descent speed and descends in VNAV PTH.

Speed Restriction Deceleration

Before the speed restriction altitude, VNAV decelerates to commanded speed

using VNAV PTH.

When at restricted speed, VNAV commands decreased pitch and descends in

VNAV PTH.

Altitude Restrictions

The VNAV path conforms to altitude restrictions at MNO, EPG, and the FAF. If

required, VNAV uses a level path until intercepting the idle thrust descent path to

the next altitude constrained waypoint.

[Option - With geometric descent path]

The VNAV path conforms to altitude restrictions at MNO, EPG, and the FAF. The

thrust mode changes to FMC SPD as required to maintain the target speed.

Approach

VNAV descends and starts approach in VNAV PTH at the commanded speed.

Missed Approach

When TOGA is pushed during approach, or when crossing the missed approach

point, VNAV disengages.

When selected during missed approach, VNAV engages in VNAV SPD.

Missed Approach Level Off

At missed approach altitude VNAV changes to VNAV PTH.

VNAV Speed Descent

A speed descent may be selected manually by selecting the SPEED prompt on the

PATH DES page. With no E/D specified, the speed descent is the only descent

mode available.

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Operation

Boeing 737 Operations Manual

The speed descent maintains the target speed. Normally, the target speed is

economy above the airspeed restriction altitude and 240 knots below that altitude,

until deceleration is necessary for the approach. VNAV will not permit descent

below the altitude restriction until the airspeed is at or below the restricted value.

The speed descent normally begins automatically at the calculated T/D, provided

the MCP altitude is reset for the descent. At the T/D, the FMC commands pitch to

maintain target descent speed. LNAV does not have to be engaged in order to fly

a VNAV speed descent.

The descent attempts to comply with waypoint altitude restrictions, and will not

violate these restrictions. The VNAV speed descent will not, however, guarantee

the airplane reaches an altitude restriction at the required point.

A speed descent cannot automatically revert to a path descent, except during

STAR, approach transition, or approach leg with a vertical angle. However, if all

required parameters for a path descent are available, a path descent may be

manually selected at any time by selecting the PATH prompt on the speed descent

page.

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Flight Management System

Operation

Boeing 737 Operations Manual

Cruise

Before the top of descent, FMC is in cruise mode and uses VNAV PTH and ECON

cruise speed.

Descent

After top of descent, FMC is in descent mode and VNAV changes to economy

descent speed and descends in VNAV SPD.

Speed Restriction Deceleration

Before the speed restriction altitude, VNAV decelerates to commanded speed

using VNAV SPD.

When at restricted speed, VNAV commands decreased pitch and descends in

VNAV SPD.

VNAV Path

During a speed descent, VNAV may not maintain the FMC computed VNAV path.

However, if E/D shows, a VNAV path is available.

Altitude Restrictions

VNAV conforms to altitude restrictions at MNO and EPG. After MNO VNAV

continues an idle thrust descent using VNAV SPD.

Upon reaching the next altitude restriction, VNAV commands level flight using

VNAV PTH. The thrust mode changes to FMC SPD.

Descent and Approach

After EPG, VNAV continues the idle thrust descent using VNAV SPD.

Prior to the approach, VNAV decelerates to approach speed. The FMC prompts

manual flap extension.

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Operation

Boeing 737 Operations Manual

Vertical Angle

A vertical angle can be assigned to a waypoint from the navigation database. This

vertical angle defines a VNAV path between the waypoint and the waypoint

preceeding it. This feature can be available in approaches, approach transitions,

and STARs. For example, the vertical angle for the glidepath of an ILS approach

would typically be 3 degrees. This angle is displayed on the ACT RTE LEGS page

above the speed/altitude line for the associated waypoint. Vertical angles may be

expected in any approach ending at RWXXX or MAXXX. The E/D will be

RWXXX or MAXXX, and the E/D altitude will be either threshold crossing

height (TCH - typically 50 feet above the touchdown zone elevation) or the

altitude specified at MAXXX.

If a path (VNAV PTH) descent is active when a vertical angle leg becomes active,

the path mode will remain active, but VNAV will follow the vertical angle rather

than the idle thrust descent path.

If the vertical angle leg becomes active during a speed descent, the VNAV mode

will change to VNAV PTH automatically, and there will be no SPEED prompt on

the descent page.

Early Descent

A descent in VNAV started before the top of descent point is an early descent. If

a path descent is planned, VNAV commands a 1000 fpm descent until the idle

descent path is intercepted. If a speed descent is planned, VNAV commands an

idle thrust descent.

To start an early descent, use DES NOW prompt on the DES page.

[Option - With speed and altitude intervention]

An early descent can also be started by pushing the altitude intervention switch.

T/D

DES NOW (VNAV PTH)

DES NOW (VNAV SPD)

DES NOW (VNAV PTH)

With a VNAV path descent planned, VNAV starts an early descent at 1000 fpm

and captures the idle descent path. VNAV uses FMC SPD for the autothrottle

mode and VNAV PTH for the pitch mode.

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Flight Management, Navigation -

Flight Management System

Operation

Boeing 737 Operations Manual

DES NOW (VNAV SPD)

With a VNAV speed descent planned, VNAV starts an idle thrust early descent.

VNAV does not attempt to capture the VNAV descent path. VNAV uses VNAV

SPD for the pitch mode and the autothrottle commands IDLE, followed by ARM.

Approach

The FMC transitions to “on approach” when the airplane is within:

•

2 NM of the first approach waypoint (including approach transitions such

as arcs and procedure turns), or

•

2000 feet of airport elevation, whichever occurs first.

When the FMC is “on approach”, the following features are available:

• UNABLE RNP alerting levels are higher

• when preparing for a missed approach and the MCP altitude is set at least

300 feet above the current airplane altitude, VNAV will continue to

command a descent

• if the airplane is more than 200 feet below the vertical path, VNAV

commands zero vertical speed until intercepting the path.

Note: Display of a specified path angle is not limited to approaches. A path angle

may be defined for a leg in a STAR and displays on the RTE LEGS page

for the procedure.

The FMC transitions out of “on approach” under the following conditions:

• selecting TO/GA

• the airplane lands

• the waypoint cycles to the first waypoint of the missed approach

• executing a direct-to waypoint in the missed approach.

The following situations are generally encountered during approach operations,

but are not determined by “on approach” logic:

• If speed intervention is engaged:

• during a path descent with flaps up on an idle leg, VNAV switches to

VNAV SPD

• with flaps down, VNAV remains in VNAV PTH

• when a point to point (geometric path) leg is active, VNAV remains in

VNAV PTH

• while a vertical angle leg (GP x.xx on RTE LEGS page) is active,

VNAV remains in VNAV PTH

• if a vertical angle leg (GP x.xx on RTE LEGS page) becomes active,

VNAV switches to VNAV PTH without pilot action

• if on a vertical angle leg, and cross track exceeds two times the RNP

value, while LNAV is not engaged, VNAV will disengage.

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Flight Management System

Operation

Boeing 737 Operations Manual

VNAV will remain engaged at all flap settings, allowing approaches to be flown

using the vertical angle guidance. Speed for final approach can be set on the

APPROACH REF page.

[Option - FMC U10.3 and later]

If an ILS approach is flown in VNAV using vertical angle guidance, VNAV will

disconnect when passing the GS-XXX point if G/S is armed, but it can be

reengaged. If the GS-XXX point is deleted, VNAV will remain engaged

throughout the approach.

For an approach without a runway waypoint on the RTE LEGS page, the VNAV

path is calculated to the MDA or a calculated altitude at the missed approach

point. The calculated altitude may be below the MDA to ensure a flight path angle

and normal threshold crossing height.

Note: It is the flight crew’s responsibility not to descend below the MDA until

adequate visual contact is achieved.

Go-Around

Below 2000 feet radio altitude, a go-around can be initiated by any of the

following methods:

• pushing either TO/GA switch while in a descent

• selecting Go-Around Thrust Limit when below MCP altitude with N1

autothrottle mode engaged

• executing a direct-to waypoint in the missed approach (other than the

missed approach point)

• automatically while in a decent and the last waypoint of the approach

cycles to the first waypoint of the missed approach.

Once the go-around is initiated:

• the thrust limit changes to go-around thrust

• the FMC transitions from active descent to active climb

• all descent altitude constraints below the current airplane altitude are

deleted and replaced with predicted altitudes

• the original destination airport (airport from which the go-around was just

initiated) becomes the new origin airport allowing SID selection if a

diversion to another airport is required.

Note: VNAV and LNAV can only be engaged when the airplane climbs above

400 feet radio altitude, unless the loaded missed approach procedure is

from the navigation database in which case VNAV and LNAV can be

engaged below 400 feet radio altitude.

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Flight Management, Navigation -

Flight Management System

Operation

Boeing 737 Operations Manual

If the go-around was initiated by pushing a TO/GA switch or selection of

go-around thrust, the CRZ ALT will change to the highest of:

• the highest constraint in the missed approach

•

1500 feet above airport elevation

• the MCP altitude.

Note: If the MCP altitude is the lowest of the three, the autopilot, if engaged, will

level off at the MCP altitude.

If the go-around was initiated by direct-to or waypoint sequencing, the CRZ ALT

will change to the highest of:

• the highest constraint in the missed approach

•

1500 feet above airport elevation.

If VNAV is engaged to fly the missed approach, the thrust limit changes to climb.

Refer to section NP20.xx, Go-Around Procedure and section 4.20, Go-Around for

additional information.

11.31.36

Flight Management, Navigation -

Flight Management System

Operation

Boeing 737 Operations Manual

Engine Out Modification

Select the ENG OUT prompt on the CRZ page. The ENG OUT page displays the

appropriate engine out driftdown performance data to enable the airplane to

descend to the engine out maximum altitude. Refer to FMC Cruise, section 11.42

for a complete description of the ENG OUT CRZ page.

Drift Down Execution

After selecting the left or right ENG OUT mode, perform the driftdown as

follows:

• disconnect A/T

• set maximum continuous thrust on operating engine (N1 line)

[Option - FMC U10.3 and later]

• set MCP speed to ENG OUT SPD

• set MCP altitude to MAX ALT or lower altitude as required

• select LVL CHG.

The airplane then descends at CON thrust and the driftdown airspeed to the MAX

ALT. As the driftdown proceeds and airplane gross weight decreases, the

maximum altitude may increase.

Note: The engine out cruise page provides advisory performance data for

operating with one engine.

Engine Out Cruise

Engine out cruise operates like normal cruise with engine out cruise speeds. If

range is a factor, determine Engine Inoperative LRC speed from the QRH. Thrust

limit remains in CON.

Required Time of Arrival (RTA)

VNAV controls cruise speed to achieve a flight crew specified arrival time at a

specified waypoint. After the appropriate waypoint and RTA are input to the FMC,

the FMC will compute a recommended takeoff time, speeds required to comply

with the RTA, and progress information for the flight. If the RTA is not achievable,

the RTA UNACHIEVABLE scratchpad message is displayed.

Data Entry Rules

Altitude Entry

Altitudes can be entered into the FMC as three digit (xxx), four digit (xxxx), five

digit (xxxxx), or flight level (FLxxx) numbers. The FMC automatically displays

altitude or flight level entries in the proper form based on the transition altitude.

Some data lines further restrict the valid entry forms.

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Flight Management System

Operation

Boeing 737 Operations Manual

Three digit entries represent altitude or flight levels in increments of 100 feet.

Leading zeros are required.

Examples of three digit (xxx, FLxxx) entries with transition altitude = 10,000 feet:

•

800 feet is entered as 008 or FL008 and displayed as 800

•

1,500 feet is entered as 015 or FL015 and displayed as 1500

•

11,500 feet is entered as 115 or FL115 and displayed as FL115

•

25,000 feet is entered as 250 or FL250 and displayed as FL250.

Four digit entries represent feet, rounded to the nearest ten feet. Leading zeros are

required. This form is used when the altitude does not exceed 9,994 feet.

Examples of four digit (xxxx) entries with transition altitude = 18,000 feet:

•

50 feet is entered as 0050 and displayed as 50

•

835 feet is entered as 0835 and displayed as 840

•

1,500 feet is entered as 1500 and displayed as 1500

•

8,500 feet is entered as 8500 and displayed as 8500

•

9,994 feet is entered as 9994 and displayed as 9990.

Five digit entries represent feet, rounded to the nearest ten feet. This form is used

when the altitude exceeds 9,994 feet.

Examples of five (xxxxx) digit entries with transition altitude = 4,000 feet:

•

50 feet is entered as 00050 and displayed as 50

•

835 feet is entered as 00835 and displayed as 840

•

1,500 feet is entered as 01500 and displayed as 1500

•

8,500 feet is entered as 08500 and displayed as FL085

•

9,995 feet is entered as 09995 and displayed as FL100

•

11,500 feet is entered as 11500 and displayed as FL115

•

25,000 feet is entered as 25000 and displayed as FL250.

Negative altitude entries are allowed to -1000 feet.

Airspeed Entry

Airspeeds can be entered into the FMC as calibrated airspeed or Mach number.

Calibrated airspeeds are entered as three digits (xxx) in knots. Mach numbers are

entered as one, two, or three digits following a decimal point.

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Flight Management, Navigation -

Flight Management System

Operation

Boeing 737 Operations Manual

Data Pairs

Many CDU pages display data in pairs separated by a slash “/.” Examples of these

pairs include wind direction/speed and waypoint airspeed/altitude restrictions.

When entering both values in a pair, the slash is inserted between the values. When

it is possible to enter only one value of the pair, the slash may not be required.

When entering only the outboard value of a pair, the trailing or leading slash may

be entered, but is not required before transferring to the data line. When entering

the inboard value of a pair, the trailing or leading slash must be entered before

transferring to the data line. Omission of the required slash normally results in an

INVALID ENTRY message.

Bearing Entry

Entry of a bearing value requires three digits. For example, key 090, not 90. A

bearing entry of 360 is displayed as 000.

Plus/Minus Signs

When entering temperature or an along-track displacement distance, positive

values are assumed by the FMC and + signs are not required. For negative values,

key in the - sign.

11.31.40

Boeing 737 Operations Manual

Flight Management, Navigation

Chapter 11

Flight Management Computer

Section 32

FMC Databases

The FMC contains two databases:

• performance database

• navigation database.

The performance database eliminates the need for the flight crew to refer to a

performance manual during flight, and provides the FMC with the information

required to calculate pitch and thrust commands. All information normally

required can be displayed on the CDU. The database includes:

• airplane drag and engine characteristics

• maximum and optimum altitudes

• maximum and minimum speeds.

Maintenance personnel can refine the database by entering correction factors for

drag and fuel flow.

The navigation database includes most information normally determined by

referring to navigation charts. This information can be displayed on the CDU or

navigation display. The database contains:

• the location of VHF navigation aids

• waypoints

• airports

• runways

• other airline selected information, such as SIDs, STARs, approaches, and

company routes.

If the permanent database does not contain all of the required flight plan data,

additional airports, navaids, and waypoints can be defined by the crew and stored

in either a supplemental or a temporary navigation database. Use of these

additional databases provides world-wide navigational capability, with the crew

manually entering desired data into the FMC via various CDU pages. Information

in the supplemental navigation database is stored indefinitely, requiring specific

crew action for erasure; the temporary navigation database is automatically erased

at flight completion.

The supplemental and temporary databases share storage capacity for forty

navaids and six airports, the entries being stored in either database on a first come,

first served basis. For the waypoint category, exclusive storage is reserved in the

temporary database for twenty entries (including those created on the RTE or RTE

LEGS pages). An additional twenty waypoints (up to a maximum of forty) can be

stored in either the temporary or supplemental database on a first come, first

served basis.

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Boeing 737 Operations Manual

When any storage capacity is full, entries which are no longer required should be

deleted by the crew to make space for additional new entries. Created waypoints

cannot be stored in the database runway category.

The FMC contains two sets of navigation data, each valid for 28 days. Each set

corresponds to the normal navigation chart revision cycle. The FMC uses the

active set for navigation calculations. The contents of the navigation database are

periodically updated and are transferred to the FMC before the expiration date of

the current data.

Thrust Management

The autothrottle operates in response to flight crew mode control panel inputs or

to automatic FMC commands. Reference thrust can be selected on the N1 LIMIT

page. Automatic FMC autothrottle commands are made while VNAV is engaged.

The autothrottle system:

• uses reference thrust limits calculated by the FMC

• commands the thrust levers

• commands thrust equalization through the electronic engine controls.

Thrust limits are expressed as N1 limits. Thrust equalization references N1.

The FMC calculates a reference thrust for the following modes:

• takeoff

• reduced climb

• derated takeoff

• cruise

• assumed temperature takeoff

• continuous

• climb

• go-around.

[Option - With takeoff bump thrust]

The FMC calculates a reference thrust for the following modes:

• takeoff

• reduced climb

• derated takeoff

• cruise

• assumed temperature takeoff

• continuous

• takeoff bump

• go-around.

• climb

[Option -With takeoff bump thrust and quiet climb]

The FMC calculates a reference thrust for the following modes:

• takeoff

• reduced climb

• derated takeoff

• cruise

• assumed temperature takeoff

• continuous

• takeoff bump

• go-around

• climb

• noise abatement (cutback).

11.32.2

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Flight Management, Navigation -

Flight Management Computer

Boeing 737 Operations Manual

The thrust reference mode automatically transitions for the respective phase of

flight. These modes can be selected on the N1 LIMIT page. The selected thrust

reference mode is displayed on the thrust mode display.

[Option - FMC U10.1 and later, with automatic thrust reduction after takeoff]

The flight crew can specify the thrust reduction height where the transition from

takeoff to climb thrust takes place by making an entry on TAKEOFF REF page 2.

Allowable entries are 800 feet to 15,000 feet.

[Option - FMC U10.3 and later]

The default value is determined by the airline and is stored in the model/engine

database.

[Option - With quiet climb]

With cutback mode selected ON, the flight crew can specify the thrust reduction

and restore altitudes on TAKEOFF REF page 2. The FMC calculates and

commands a cutback thrust rating based on data provided through the

model/engine database. In addition the FMC uses the reduction altitude to

calculate the required cutback altitude. A new N1 is calculated during climb and

normal climb thrust is restored at the RESTORE altitude.

Reduced Thrust Takeoff

Reduced thrust takeoffs lower EGT and extend engine life. They are used

whenever performance limits and noise abatement procedures permit.

Takeoff Derate

[Option - FMC U10.1 and later]

Fixed derates can be selected on the N1 LIMIT page. Performance data for these

derates is provided in the Airplane Flight Manual (AFM).

With derated takeoff selected, 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 while on the ground. Use the takeoff

speeds supplied by the FMC or specified in Chapter PI, Performance-Inflight, for

the selected derate condition.

Derated takeoff rating can be further reduced by assumed temperature.

[Option - With FMC computed QRH takeoff speeds]

Use the takeoff speeds provided by the FMC or specified in Chapter PI,

Performance-Inflight, for the selected derate or variable takeoff rating condition.

Use the takeoff speeds specified in Chapter PI, Performance-Inflight, for the

selected derate or variable takeoff rating condition.

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Boeing 737 Operations Manual

Assumed Temperature Thrust Reduction Takeoff

[Option - FMC U10.1 and later]

A takeoff thrust less than the full rated thrust may be achieved by using an

assumed temperature that is higher than the actual temperature. The desired thrust

level is obtained through entry of a SEL TEMP value on the N1 LIMIT page or

TAKEOFF REF page 2. Use approved sources for selecting the assumed

temperature.

The maximum thrust reduction authorized is 25 percent below any certified rating.

Do not use assumed temperature reduced thrust if conditions exist that affect

braking, such as slush, snow, or ice on the runway, or if potential windshear

conditions exist.

If the assumed temperature method is applied to a fixed derate, application of

additional power should not exceed the fixed derate N1 limit as loss of directional

control could occur while on the ground.

When the assumed temperature method is used with full rate, the reduced thrust

setting is not considered a limitation. If conditions are encountered where

additional thrust is desired, the crew can manually apply full thrust.

Takeoff Bump Thrust

[Option]

Takeoff bump thrust may be used to meet extra thrust requirements for takeoff at

certain airports. Takeoff bump thrust provides thrust above normal maximum

takeoff thrust. The takeoff thrust bump setting may be selected on the N1 LIMIT

page. Takeoff thrust bump is only available for takeoff, and cannot be applied to

go around, max continuous, or climb thrust ratings. If takeoff thrust bump is

selected, assumed temperature reduced thrust is not available.

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.

11.32.4

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Boeing 737 Operations Manual

Fuel Monitoring

The FMC receives fuel data from the fuel quantity indicating system. Fuel

quantity values show on the PERF INIT page and on PROGRESS page 1/3.

The scratchpad message VERIFY GW AND FUEL shows if total fuel quantity

data is invalid. The PERF INIT page FUEL line changes to dashes. The FMC uses

the last valid fuel quantity for performance predictions and VNAV operation. The

flight crew should manually enter estimated fuel weight. Periodic fuel weight

update is required for the remainder of the flight to keep gross weight current. The

FMC does not update the manual fuel weight entry. The scratchpad message

VERIFY GW AND FUEL shows again each 30 minutes if subsequent entries are

not performed. The scratchpad message does not show during descent with Vref

selected.

The scratchpad message CHECK FMC FUEL QUANTITY shows if the FMC has

detected an unexpected drop in fuel quantity.

The FMC continually estimates the amount of fuel that will remain when the

destination airport is reached if the active route is flown. The CDU message

USING RSV FUEL is displayed if the estimate is less than the fuel reserve value

entered on the PERF INIT page. The CDU message INSUFFICIENT FUEL is

displayed if predicted fuel at destination will be 2000 lb (900 kg) or less.

Loss of FMC Electrical Power

The FMC requires continuous electrical power to operate. When the electrical

power is interrupted for less than ten seconds:

• LNAV and VNAV disengage

• all entered data is retained by the FMC

• the FMC resumes normal operation when power is restored.

If power is lost for ten seconds or more on the ground, all preflight procedures and

entries must be done again when power is restored.

If power is lost for more than ten seconds in flight:

• LNAV and VNAV disengage

• all entered data is retained by the FMC, and when power is restored the

RTE LEGS page is displayed with the scratchpad message

SELECT ACTIVE WPT/LEG.

Before LNAV can engage, the FMC must be instructed how to return to the route.

Select the desired active waypoint and proceed direct or intercept a course to the

waypoint.

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Boeing 737 Operations Manual

FMC Failure

[Option - Dual FMC]

Single FMC Failure

The FMC/CDU is designed to automatically preserve the most capable modes of

navigation and guidance that can be maintained with the equipment and

navigation aids available. If an error or system failure results in reduced capability,

then the FMC may generate a crew message for display in the CDU scratchpad. If

other system inputs to the FMC should fail, affected CDU displays are blanked to

prevent the display of misleading or erroneous data. For example, loss of the total

fuel input causes some performance related data to be blank. The messages and

FMC internal responses provide an orderly transition from full FMC guided flight

to less automated capability.

If the right FMC fails, the FMC alert light and the FMC message light will

illuminate. The message SINGLE FMC OPERATION will be displayed in both

scratchpads. VTK will display on the right navigation display. LNAV and VNAV

will disengage if autopilot B is in use (can be reengaged if autopilot A is selected).

After

25 to

30 seconds, the right navigation display will display failure

information. The right navigation display may be restored by placing the FMC

source select switch to BOTH ON L.

Note: If the above indications are observed with no VTK on the right navigation

display, there is a disagreement between left and right FMC data. Moving

the FMC Source Select Switch to BOTH ON L should allow the two FMCs

to resynchronize. The switch may then be returned to NORMAL when the

message DUAL FMC OP RESTORED is displayed on both scratch pads.

[Option - MCDU]

If the left FMC fails, the FMC alert light will illuminate. The MENU page will

appear on both CDUs. VTK will appear on the left navigation display. LNAV and

VNAV will disengage, but can be reengaged if autopilot B is in use or is selected.

After 25 to 30 seconds, the left navigation display will display failure information.

To restore full operation, the FMC source select switch must be moved to BOTH

ON R.

[Option - FMC U10.2 and later]

Note: During an FMC software restart, the navigation display map track may

rapidly slew to 0 degrees then to the correct value.

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Boeing 737 Operations Manual

Dual FMC Failure

[Option - MCDU]

If both FMCs fail, the FMC alert light will illuminate. The MENU page will

appear on both CDUs. VTK will appear on both navigation displays. LNAV and

VNAV will disengage. After 25 to 30 seconds, both navigation displays will

display failure information.

FMC Failure

[Option - Single FMC]

[Option - CDU]

If the FMC fails, the FMC alert light will illuminate. The FMC/CDU FAIL light

will appear on both CDUs, and both CDUs will display failure modes. VTK will

appear on both navigation displays. LNAV and VNAV will disengage. After 25 to

30 seconds, both navigation displays will display failure information.

[Option - MCDU]

If the FMC fails, the FMC alert light will illuminate. The MENU page will appear

on both CDUs. VTK will appear on both navigation displays. LNAV and VNAV

will disengage. After 25 to 30 seconds, both navigation displays will display

failure information.

[Option - FMC U10.2 and later]

Note: During an FMC software restart, the navigation display map track may

rapidly slew to 0 degrees then to the correct value.

11.32.7

Boeing 737 - 600/700/800/900. Operations Manual (1997 year) - page 59