flight management, navigation r 01 in boing 737 seri

of 43PT. METRO BATAVIAPT. METRO BATAVIADirectorate of OperationalDirectorate of Operational

737-300/400737-300/400FLIGHT MANAGEMENT, FLIGHT MANAGEMENT,

NAVIGATIONNAVIGATION

NextNextMain MenuMain Menu QuitQuit


Control Display Unit (CDU)Control Display Unit (CDU)


Control Display Unit (CDU)Control Display Unit (CDU)Control Display Unit (CDU) Display:Control Display Unit (CDU) Display:Shows Flight Management System (FMS) data Shows Flight Management System (FMS) data pages.pages.



Scratchpad:Scratchpad:Shows messages, alpha-numeric entries or line Shows messages, alpha-numeric entries or line selected data.selected data.

SCRATCHPAD AREA



Line Select Keys:Line Select Keys:Push –Push –• Moves data from scratchpad to selected line.Moves data from scratchpad to selected line.• Moves data from selected line to scratchpad.Moves data from selected line to scratchpad.• Selects page, procedure, or performance Selects page, procedure, or performance mode as applicable.mode as applicable.• Deletes data from selected line when DELETE Deletes data from selected line when DELETE

is shown in scratchpad.is shown in scratchpad.

Line select keys are identified from top to Line select keys are identified from top to bottom (1-6) and left (L) or right (R). For bottom (1-6) and left (L) or right (R). For example, the top key on the left-hand side is example, the top key on the left-hand side is identified as “1L”.identified as “1L”.

1L1L

2L2L

3L3L

4L4L

5L5L

6L6L

1R1R

2R2R

3R3R

4R4R

5R5R

6R6R



BRT Control:BRT Control:Rotate –Rotate –Controls display brightness.Controls display brightness.



FAIL Light:FAIL Light:Illuminated –Illuminated –The Flight Management Computer (FMC) has The Flight Management Computer (FMC) has failed.failed.

FAIL



MSG Light:MSG Light:Illuminated –Illuminated –Scratchpad message is shown. Scratchpad message is shown.

Example shown in scratchpad indicates that Example shown in scratchpad indicates that the IRS has automatically restarted the the IRS has automatically restarted the alignment process due to the detection of alignment process due to the detection of excessive motion of the aircraft.excessive motion of the aircraft.

MSG

IRS MOTION


Control Display Unit (CDU)Control Display Unit (CDU)CDU Function Keys:CDU Function Keys:Push –Push –• INIT REFINIT REF: Shows page for data initialization or for : Shows page for data initialization or for

reference data.reference data.• RTERTE: Shows page to input or change origin, destination or : Shows page to input or change origin, destination or

route.route.• CLBCLB: Shows page to view or change climb data.: Shows page to view or change climb data.• CRZCRZ: Shows page to view or change cruise data.: Shows page to view or change cruise data.• DESDES: Shows page to view or change descent data.: Shows page to view or change descent data.• DIR INTCDIR INTC: Shows page to modify route to fly directly from : Shows page to modify route to fly directly from

present position to any waypoint or to intercept any course present position to any waypoint or to intercept any course to any waypoint.to any waypoint.

• LEGSLEGS: Shows page to evaluate or modify lateral and : Shows page to evaluate or modify lateral and vertical data; shows page to control PLAN mode display.vertical data; shows page to control PLAN mode display.

• DEP ARRDEP ARR: Shows page to input or change departure and : Shows page to input or change departure and arrival procedures.arrival procedures.

• HOLDHOLD: Shows page to create holding patterns and show : Shows page to create holding patterns and show holding pattern data.holding pattern data.

• PROGPROG: Shows page to view dynamic flight and navigation : Shows page to view dynamic flight and navigation data, including waypoint and destination ETAs, fuel data, including waypoint and destination ETAs, fuel remaining, and arrival estimates.remaining, and arrival estimates.

• NN11 LIMIT LIMIT: Shows page to view or change N: Shows page to view or change N11 thrust limits. thrust limits.• FIXFIX: Shows page to create reference point on map display.: Shows page to create reference point on map display.• PREV PAGEPREV PAGE: Shows previous page of related pages.: Shows previous page of related pages.• NEXT PAGENEXT PAGE: Shows next page of related pages.: Shows next page of related pages.



EXEC (Execute) Light:EXEC (Execute) Light:Illuminated –Illuminated –Active data is modified, but not executed.Active data is modified, but not executed.



EXEC (Execute) Key:EXEC (Execute) Key:Push –Push –• Makes data modification(s) active.Makes data modification(s) active.• Extinguishes execute light.Extinguishes execute light.



Alpha/Numeric Keys:Alpha/Numeric Keys:Push –Push –• Enters selected character or number in Enters selected character or number in scratchpad.scratchpad.• Slash (/) key enters “/” in scratchpad.Slash (/) key enters “/” in scratchpad.• Plus/Minus (+/-) key enters a “-” symbol in Plus/Minus (+/-) key enters a “-” symbol in

scratchpad. Subsequent pushes will alternate scratchpad. Subsequent pushes will alternate between “+” and “-”.between “+” and “-”.



DEL Key:DEL Key:Push –Push –Enters DELETE in scratchpad. The user may Enters DELETE in scratchpad. The user may now select the data to be deleted by pressing now select the data to be deleted by pressing the respective line select key.the respective line select key.

DELETE



CLR Key:CLR Key:Push –Push –• Clears the last scratchpad character.Clears the last scratchpad character.• Clears scratchpad message.Clears scratchpad message.

Push and hold –Push and hold –Clears all scratchpad data.Clears all scratchpad data.


Control Display Unit (CDU)Control Display Unit (CDU)Page Title:Page Title:Subject or name of data shown on page. Subject or name of data shown on page.

Example shown is the POS INIT (position Example shown is the POS INIT (position initialization) page. initialization) page.

POS INIT 1 / 3L A S T P O S

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Control Display Unit (CDU)Control Display Unit (CDU)Page Number:Page Number:The left number is the number of the page that The left number is the number of the page that is currently being viewed. The second number is currently being viewed. The second number is the total number of related pages. This is the total number of related pages. This example indicates that page one of three is example indicates that page one of three is currently being viewed. currently being viewed.


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Control Display Unit (CDU)Control Display Unit (CDU)Line Title:Line Title:Title of data on line below.Title of data on line below.POS INIT 1 / 3

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Control Display Unit (CDU)Control Display Unit (CDU)Line:Line:Shows prompts (dashed lines or boxed), Shows prompts (dashed lines or boxed), selections, options or data.selections, options or data.


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Control Display Unit (CDU)Control Display Unit (CDU)Box Prompts:Box Prompts:Data input is mandatory. Data input is mandatory. POS INIT 1 / 3


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Control Display Unit (CDU)Control Display Unit (CDU)Dashed Lines:Dashed Lines:Data input is optional. Data input is optional. POS INIT 1 / 3


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FMC Alert LightFMC Alert LightFMC P/RST (FMC Push To Reset) Alert Light:FMC P/RST (FMC Push To Reset) Alert Light:Illuminated amber –Illuminated amber –• The FAIL lights on both CDU’s are illuminated.The FAIL lights on both CDU’s are illuminated.• An alerting message exists for both CDU’s.An alerting message exists for both CDU’s.• Disengage light test switch held in No. 1 or No. 2 Disengage light test switch held in No. 1 or No. 2

position.position.

This concludes the review of the This concludes the review of the CDU. The next section will discussCDU. The next section will discuss

the IRS panels.the IRS panels. Click Click NextNext to continue. to continue.


IRS Display Unit (ISDU)IRS Display Unit (ISDU)


IRS Display Unit (ISDU)IRS Display Unit (ISDU)IRS (Inertial Reference System) DISPLAY:IRS (Inertial Reference System) DISPLAY:Two windows display data for the selected Two windows display data for the selected Inertial Reference Unit (IRU). Selection of an Inertial Reference Unit (IRU). Selection of an IRU is made via the system display selector IRU is made via the system display selector (SYS DSPL) –(SYS DSPL) –• Type of data displayed is normally determined Type of data displayed is normally determined

by the display selector (DSPL SEL).by the display selector (DSPL SEL).• Keyboard entry of present position or Keyboard entry of present position or magnetic heading overrides the selected magnetic heading overrides the selected display.display.• Last digit of each window is for a decimal Last digit of each window is for a decimal

place (tenths). place (tenths).


IRS Display Unit (ISDU)IRS Display Unit (ISDU)DSPL SEL (Display Selector):DSPL SEL (Display Selector):TEST (spring-loaded to TK/GS) –TEST (spring-loaded to TK/GS) –All lights in data displays and on mode selector unit All lights in data displays and on mode selector unit momentarily illuminate, followed by a ten second self-test.momentarily illuminate, followed by a ten second self-test.TK/GS –TK/GS –• Left window displays present true track (course).Left window displays present true track (course).• Right window display present ground speed (knots).Right window display present ground speed (knots).PPOS –PPOS –• Left window displays present latitude.Left window displays present latitude.• Right window displays present longitude.Right window displays present longitude.WIND –WIND –• Left window displays present inflight true wind Left window displays present inflight true wind direction.direction.• Right window displays present inflight wind speed Right window displays present inflight wind speed

(knots).(knots).HDG/STS –HDG/STS –• Left window displays present true heading.Left window displays present true heading.• Right window displays any applicable maintenance Right window displays any applicable maintenance

status codes.status codes.• During alignment, right window displays the minutes During alignment, right window displays the minutes

remaining until alignment is complete. (As the remaining until alignment is complete. (As the alignment begins, a “7” will initially be displayed. The alignment begins, a “7” will initially be displayed. The

“7” will remain in the display until time remaining is “6”. “7” will remain in the display until time remaining is “6”. Countdown will continue until time remaining is “0”.)Countdown will continue until time remaining is “0”.)


IRS Display Unit (ISDU)IRS Display Unit (ISDU)BRT Control:BRT Control:Rotate –Rotate –Adjusts brightness of the data displays. Adjusts brightness of the data displays.


IRS Display Unit (ISDU)IRS Display Unit (ISDU)SYS DSPL (System Display) Selector:SYS DSPL (System Display) Selector:L –L –Selects the left IRU for the two data displays.Selects the left IRU for the two data displays.

R –R –Selects the right IRU for the two data displays.Selects the right IRU for the two data displays.


IRS Display Unit (ISDU)IRS Display Unit (ISDU)Keyboard:Keyboard:Push –Push –• Alpha Keys:Alpha Keys:

Data displays are controlled by the Data displays are controlled by the keyboard when the N, S, E, W (latitude/ keyboard when the N, S, E, W (latitude/ longitude) or H (heading) keys are pressed.longitude) or H (heading) keys are pressed. Pressing an alpha key arms the keyboard Pressing an alpha key arms the keyboard

for numeric entries.for numeric entries.

• Numeric Keys:Numeric Keys: Permit manual entry of present position Permit manual entry of present position when ALIGN light is illuminated.when ALIGN light is illuminated. Permit manual entry of magnetic heading Permit manual entry of magnetic heading

when either mode selector is in ATT.when either mode selector is in ATT.


IRS Display Unit (ISDU)IRS Display Unit (ISDU)ENT Key:ENT Key:Cue lights illuminated –Cue lights illuminated –N, S, E, W, or H entries are being keyed.N, S, E, W, or H entries are being keyed.

Push –Push –Keyed data is entered into IRU’s following Keyed data is entered into IRU’s following completion of valid self-test for reasonableness. completion of valid self-test for reasonableness. If reasonableness test passes, cue lights If reasonableness test passes, cue lights extinguish. extinguish.

Note: The cue lights are two small white lights Note: The cue lights are two small white lights located directly below the “ENT”.located directly below the “ENT”.


IRS Display Unit (ISDU)IRS Display Unit (ISDU)CLR Key:CLR Key:Cue lights illuminated –Cue lights illuminated –An entry (ENT) attempt has failed. Entry not An entry (ENT) attempt has failed. Entry not accepted by IRU’s.accepted by IRU’s.

Push –Push –Extinguishes cue lights and clears data display Extinguishes cue lights and clears data display of any data not yet entered or accepted. of any data not yet entered or accepted.

Note: The cue lights are two small white lights Note: The cue lights are two small white lights located directly below the “CLR”.located directly below the “CLR”.


IRS Mode Selector UnitIRS Mode Selector Unit


IRS Mode Selector UnitIRS Mode Selector UnitALIGN Lights:ALIGN Lights:Illuminated –Illuminated –• Steady: The related IRU is operating in the Steady: The related IRU is operating in the

ALIGN mode, the initial ATT mode, or the ALIGN mode, the initial ATT mode, or the shutdown cycle.shutdown cycle.• Flashing: IRU alignment not complete due to –Flashing: IRU alignment not complete due to –• IRU detection of aircraft movement, orIRU detection of aircraft movement, or• No present position entry, or No present position entry, or • Significant difference between previous and Significant difference between previous and

entered positions. A significant difference is entered positions. A significant difference is defined as more than one degree difference defined as more than one degree difference between lat/long entered and lat/long stored between lat/long entered and lat/long stored in IRU memory.in IRU memory.

Extinguished –Extinguished –• The related IRU is not operating in the ALIGN The related IRU is not operating in the ALIGN

mode.mode.• With mode selector in NAV, alignment is With mode selector in NAV, alignment is complete and all IRU information is available.complete and all IRU information is available.• With mode selector in ATT, attitude information With mode selector in ATT, attitude information

is available. Heading information is available is available. Heading information is available following entry of initial magnetic heading.following entry of initial magnetic heading.


IRS Mode Selector UnitIRS Mode Selector UnitON DC Lights:ON DC Lights:Illuminated –Illuminated –• The related IRU is operating on its DC power The related IRU is operating on its DC power source. AC power is not normal.source. AC power is not normal.• If on the ground, the ground call horn (located in If on the ground, the ground call horn (located in

nose wheel well) sounds to alert the maintenance crew nose wheel well) sounds to alert the maintenance crew that a battery drain condition exists.that a battery drain condition exists.

• Momentary illumination is normal during the first Momentary illumination is normal during the first few seconds after initiating the alignment process.few seconds after initiating the alignment process.

Switched hot battery bus

Switched hot battery bus

Alternate Power (DC)

Transfer bus 2AC standby busNormal Power

(AC)

Right IRULeft IRU

Note: If the right IRU loses power from its normal Note: If the right IRU loses power from its normal source, it will automatically receive power from its source, it will automatically receive power from its alternate source (ON DC light illuminates). Five minutes alternate source (ON DC light illuminates). Five minutes later, the right IRU will load shed to conserve battery later, the right IRU will load shed to conserve battery power, and therefore lose its alignment.power, and therefore lose its alignment.

The chart below indicates the normal (AC) and alternate The chart below indicates the normal (AC) and alternate (DC) power sources for the IRU’s.(DC) power sources for the IRU’s.


IRS Mode Selector UnitIRS Mode Selector UnitFAULT Lights:FAULT Lights:Illuminated –Illuminated –A system fault affecting the related IRU has been A system fault affecting the related IRU has been detected.detected.

Note: In order to determine exactly which type of Note: In order to determine exactly which type of FAULT has occurred, the maintenance crew will FAULT has occurred, the maintenance crew will rotate the DSPL SEL switch to HDG/STS. This rotate the DSPL SEL switch to HDG/STS. This will display a number (1 thru 10) in the IRS data will display a number (1 thru 10) in the IRS data display. This number is then matched up against display. This number is then matched up against an “IRS malfunction code” chart. an “IRS malfunction code” chart.


IRS Mode Selector UnitIRS Mode Selector UnitDC FAIL Lights:DC FAIL Lights:Illuminated –Illuminated –DC power for the related IRU is not normal. DC power for the related IRU is not normal.

Note: If Note: If oneone DC FAIL light is the only light DC FAIL light is the only light illuminated, and the other lights are extinguished, illuminated, and the other lights are extinguished, the related IRU should be operating normally on its the related IRU should be operating normally on its AC power source. If AC power source. If bothboth DC FAIL lights are DC FAIL lights are illuminated, the switched hot battery bus is not illuminated, the switched hot battery bus is not powered, or the battery may be nearly discharged. powered, or the battery may be nearly discharged.


IRS Mode Selector UnitIRS Mode Selector UnitIRS Mode Selectors:IRS Mode Selectors:OFF –OFF –All electrical power is removed from the system after a 30 All electrical power is removed from the system after a 30 second shutdown cycle.second shutdown cycle.

ALIGN –ALIGN –• Rotating the selector from OFF to ALIGN initiates the Rotating the selector from OFF to ALIGN initiates the

alignment cycle.alignment cycle.• Rotating the selector from NAV to ALIGN automatically Rotating the selector from NAV to ALIGN automatically

updates alignment and zeros ground speed error.updates alignment and zeros ground speed error.

NAV –NAV –• System enters the NAV mode after completion of the System enters the NAV mode after completion of the

alignment cycle and entry of present position (lat/long).alignment cycle and entry of present position (lat/long).• In the NAV mode, all IRU information is available In the NAV mode, all IRU information is available

to aircraft systems for normal operations.to aircraft systems for normal operations.

ATT –ATT –• Provides only attitude and heading information.Provides only attitude and heading information.

Attitude information is invalid (attitude flag in view) Attitude information is invalid (attitude flag in view) until related ALIGN light is extinguished.until related ALIGN light is extinguished.

Heading information is invalid (heading flags in view) Heading information is invalid (heading flags in view) until the actual magnetic heading is manually entered until the actual magnetic heading is manually entered and the related ALIGN light is extinguished.and the related ALIGN light is extinguished.

Position and ground speed information is not Position and ground speed information is not available until the IRS is aligned on the ground.available until the IRS is aligned on the ground. The selector must be cycled OFF before reselecting The selector must be cycled OFF before reselecting

ALIGN or NAV.ALIGN or NAV.


Attitude Transfer SwitchAttitude Transfer Switch

ATTITUDE Transfer Switch:ATTITUDE Transfer Switch:BOTH ON 1 –BOTH ON 1 –Attitude references come from IRS No. 1 (left).Attitude references come from IRS No. 1 (left).

NORMAL –NORMAL –Attitude references come from respective IRS Attitude references come from respective IRS (left or right).(left or right).

BOTH ON 2 –BOTH ON 2 –Attitude references come from IRS No. 2 (right).Attitude references come from IRS No. 2 (right).

This concludes the review of the IRS panels. This concludes the review of the IRS panels. The remainder of the presentation will discuss the Flight Management System (FMS) The remainder of the presentation will discuss the Flight Management System (FMS)

and IRS in greater detail. Click and IRS in greater detail. Click NextNext to continue. to continue.


Flight Management System (FMS)Flight Management System (FMS)The Flight Management System is comprised of the following components:The Flight Management System is comprised of the following components:

• Flight management computer (FMC)Flight management computer (FMC)• Autopilot/flight director system (AFDS)Autopilot/flight director system (AFDS)• Autothrottle (A/T)Autothrottle (A/T)• Inertial reference system (IRS)Inertial reference system (IRS)

Each of these components is an independent system and can be used independently or in various Each of these components is an independent system and can be used independently or in various combinations. The term FMS refers to the concept of joining these independent components into one combinations. The term FMS refers to the concept of joining these independent components into one integrated system which provides continuous automatic navigation, guidance, and performance integrated system which provides continuous automatic navigation, guidance, and performance management.management.

The integrated FMS provides centralized flight deck control of the aircraft’s flight path and performance The integrated FMS provides centralized flight deck control of the aircraft’s flight path and performance parameters. The FMC performs navigational and performance computations, as well as control and parameters. The FMC performs navigational and performance computations, as well as control and guidance commands.guidance commands.

The FMC utilizes crew entered flight plan information, aircraft systems data, and information from the The FMC utilizes crew entered flight plan information, aircraft systems data, and information from the FMC navigation/performance database to calculate aircraft present position. Pitch, roll and thrust FMC navigation/performance database to calculate aircraft present position. Pitch, roll and thrust commands are also calculated by the FMC. The FMC sends these commands to the autothrottle, commands are also calculated by the FMC. The FMC sends these commands to the autothrottle, autopilot, and flight director in an effort to fly an optimum flight profile. autopilot, and flight director in an effort to fly an optimum flight profile.

See picture of See picture of FMCFMC


Inertial Reference Units (IRU’s)Inertial Reference Units (IRU’s)Two independent Inertial Reference Units are installed, and are located in the Electronics and Equipment Two independent Inertial Reference Units are installed, and are located in the Electronics and Equipment bay (E&E Bay). Each IRU has three laser gyros and three accelerometers which sense angular rates and bay (E&E Bay). Each IRU has three laser gyros and three accelerometers which sense angular rates and linear accelerations, respectively. The main function of each IRU is to sense and compute linear linear accelerations, respectively. The main function of each IRU is to sense and compute linear accelerations and angular turning rates about the aircraft’s pitch, roll, and yaw axes. The IRU’s are the accelerations and angular turning rates about the aircraft’s pitch, roll, and yaw axes. The IRU’s are the aircraft’s sole source of attitude and heading information (except for the standby attitude indicator and aircraft’s sole source of attitude and heading information (except for the standby attitude indicator and standby magnetic compass).standby magnetic compass).

In their normal navigation (NAV) mode, the IRU’s combine with air data inputs to provide attitude (pitch, In their normal navigation (NAV) mode, the IRU’s combine with air data inputs to provide attitude (pitch, roll, yaw), heading (true & magnetic), wind data (speed & direction), acceleration, vertical speed, ground roll, yaw), heading (true & magnetic), wind data (speed & direction), acceleration, vertical speed, ground speed, track, and present position to the appropriate aircraft systems. IRU outputs are independent of speed, track, and present position to the appropriate aircraft systems. IRU outputs are independent of external navigation aids. external navigation aids.

See picture of See picture of IRU’SIRU’S


IRU AlignmentIRU alignment consists of determining local vertical and initial heading. Both accelerometer and laser gyro inputs are used for alignment. The aircraft must remain stationary during the alignment process. The alignment computations use the basic premise that the only accelerations during alignment are due to earths gravity, and the only motion during alignment is due to earths rotation. Accelerations due to gravity are always perpendicular to the earth’s surface and thus define local vertical. This local vertical is used to erect the attitude data so that it is accurately referenced to vertical. Once vertical is established, the laser gyro sensed earth rate components are used to establish the heading of the aircraft. As the alignment continues, both vertical reference and heading are fine tuned for maximum accuracy.

Starting point

LatitudeLongitu

de

Earths Rotation


IRU AlignmentThe orientation of the vertical axis relative to the earth’s surface is based on the present position input by the pilot into the IRU’s. Present position can be made at any time during the ten minute alignment period. Earth rate sensing by the laser gyros allows the IRU’s to determine initial latitude. This gyro determined latitude is compared to the crew entered latitude. Crew entered longitude is compared to the last stored longitude. These comparisons must be favorable to complete the alignment period.

Starting point

LatitudeLongitu

de

Earths Rotation


IRU AlignmentIRU AlignmentNormal alignment (between 70Normal alignment (between 70° 12’ north and ° 12’ north and 7070° 12’ south latitudes) is initiated by rotating the IRU mode ° 12’ south latitudes) is initiated by rotating the IRU mode selector switches from OFF, through ALIGN, to NAV. The IRU’s perform a short power test, during which selector switches from OFF, through ALIGN, to NAV. The IRU’s perform a short power test, during which the ON DC lights illuminate. When the ON DC lights extinguish and the ALIGN lights illuminate, the the ON DC lights illuminate. When the ON DC lights extinguish and the ALIGN lights illuminate, the alignment process has begun.alignment process has begun.

It is recommended that pIt is recommended that present position be entered soon after rotating the mode selector switches to resent position be entered soon after rotating the mode selector switches to NAV, but can be entered at any time during the ten minute alignment period. Present position is normally NAV, but can be entered at any time during the ten minute alignment period. Present position is normally entered utilizing the FMC CDU position initialization (POS INIT) page. If the FMC CDU is not available, entered utilizing the FMC CDU position initialization (POS INIT) page. If the FMC CDU is not available, present position may be entered utilizing the ISDU keyboard. The IRU’s will automatically enter the NAV present position may be entered utilizing the ISDU keyboard. The IRU’s will automatically enter the NAV mode after the alignment period has completed, and the aircraft may now be moved.mode after the alignment period has completed, and the aircraft may now be moved.

POS INITL A S T P O S


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POS INIT pagePOS INIT page ISDU keyboardISDU keyboard


IRU AlignmentIRU AlignmentDuring through-flights with brief ground times, a 30 second “quick” alignment may be performed. A During through-flights with brief ground times, a 30 second “quick” alignment may be performed. A “quick” align will zero the velocity errors and level the system. Simply rotate the MSU switches from “quick” align will zero the velocity errors and level the system. Simply rotate the MSU switches from NAV to ALIGN, and back to NAV. This will result in the illumination of the ALIGN lights for 30 seconds. NAV to ALIGN, and back to NAV. This will result in the illumination of the ALIGN lights for 30 seconds. With the ALIGN lights illuminated, enter a present position to improve system alignment. After the 30 With the ALIGN lights illuminated, enter a present position to improve system alignment. After the 30 second re-leveling process is complete, the IRU’s automatically revert to the NAV mode, and the ALIGN second re-leveling process is complete, the IRU’s automatically revert to the NAV mode, and the ALIGN lights extinguish. The above sequence should only be accomplished when the aircraft is not moving.lights extinguish. The above sequence should only be accomplished when the aircraft is not moving.

High latitude alignment (from 70High latitude alignment (from 70° 12’ north to ° 12’ north to 7878° 15’ north, and from ° 15’ north, and from 7070° 12’ south to ° 12’ south to 7878° 15’ south) ° 15’ south) require an extended alignment time. Alignment is initiated by rotating the MSU switch from OFF to require an extended alignment time. Alignment is initiated by rotating the MSU switch from OFF to ALIGN. After 17 minutes the MSU switch must be rotated to the NAV position. The IRS will then ALIGN. After 17 minutes the MSU switch must be rotated to the NAV position. The IRS will then immediately enter the NAV mode. Above immediately enter the NAV mode. Above 7878° 15’ north, and below ° 15’ north, and below 7878° 15’ south, the IRU’s cannot be ° 15’ south, the IRU’s cannot be accurately aligned.accurately aligned.

Magnetic variation between Magnetic variation between 7373° north and ° north and 6060° south is stored in each IRU memory. The data ° south is stored in each IRU memory. The data corresponding to the present position is combined with the true heading to determine magnetic heading.corresponding to the present position is combined with the true heading to determine magnetic heading.


Loss of IRU AlignmentLoss of IRU AlignmentIRU alignment may be lost if:IRU alignment may be lost if:• An internal fault is detected within an IRU, orAn internal fault is detected within an IRU, or• If the MSU switch is moved out of the NAV position, orIf the MSU switch is moved out of the NAV position, or• If there is a total loss of both AC and DC electrical power.If there is a total loss of both AC and DC electrical power.

If alignment is lost (but not electrical power) to an IRU while in flight, the NAV mode (including present If alignment is lost (but not electrical power) to an IRU while in flight, the NAV mode (including present position and ground speed outputs) is inoperative for the remainder of the flight. However, selecting ATT position and ground speed outputs) is inoperative for the remainder of the flight. However, selecting ATT places the IRU into a reversionary mode of operation, which will eventually supply heading and attitude places the IRU into a reversionary mode of operation, which will eventually supply heading and attitude information. After approximately 30 seconds of un-accelerated, straight & level flight, the IRU will re-level information. After approximately 30 seconds of un-accelerated, straight & level flight, the IRU will re-level and attitude reference should be restored. In order to restore heading information while in the ATT mode, and attitude reference should be restored. In order to restore heading information while in the ATT mode, the crew must manually enter the magnetic heading into the affected IRU. This can be done via the FMC the crew must manually enter the magnetic heading into the affected IRU. This can be done via the FMC CDU or the ISDU keyboard. Precession of up to 15CDU or the ISDU keyboard. Precession of up to 15° per hour can occur. Therefore, while in the ATT ° per hour can occur. Therefore, while in the ATT mode, the magnetic compass must be periodically cross-checked and an updated magnetic heading mode, the magnetic compass must be periodically cross-checked and an updated magnetic heading entered in to the affected IRU, as required.entered in to the affected IRU, as required.

flight management, navigation r 01 in boing 737 seri

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