*
ADIRU internal fault.

If the ADIRU fails the latitude compare test and you enter the same position again, the ADIRU goes back into the align mode. The CDU message REALIGNMENT INITIATED shows.
When the ADIRU completes the alignment and goes into the NAV mode, line data field 5R on the CDU POS INIT page goes blank.
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ADIRS -ALIGNMENT

Align Reset Mode
If the airplane moves during alignment, the ADIRU senses the movement and goes into the align reset mode. When airplane movement stops, the ADIRU align mode starts over. In the align reset mode, you may not enter inertial position data. Line data field 5R on the CDU POS INIT page is blank.
Auto Nav Realign Mode
If the ADIRU is in the NAV mode and the airplane does not move for six to fifteen minutes, the ADIRU enters the auto nav realign mode. This mode lets the crew update the ADIRU inertial position after a flight leg. When the ADIRU goes into the auto nav realign mode, dash prompts show on line data field 5R of the CDU POS INIT page. The dash prompts show that you may enter a new position. It is not necessary to enter a new position.
During auto nav realign, the ADIRU sets any velocity errors to zero and corrects this data:
*
Pitch attitude

*
Roll attitude

*
Heading.

If the crew enters a new position, the ADIRU does position and latitude compare tests. These tests are the same tests as the initialization mode. The only difference is the position compare test uses current ADIRU position and not NVM stored position if GPS data is not available.
Two seconds after the crew enters a position, line data field 5R on the CDU POS INIT page goes back to dashes. This lets the crew enter position updates as necessary.
If the position compare and latitude compare tests pass, the ADIRU uses the last entered position as the start point for the next flight.
If the ADIRU detects motion before the six to fifteen minute period ends, the ADIRU does not go into the auto nav realign mode and goes back to the NAV mode. The ADIRU then uses the last calculated position as the start point for the next flight leg.
Inertial Origin Disagree
If the flight management computer system (FMCS) has an origin airport in the active flight plan, the ADIRU compares the entered position with the position of the airport from the navigation data base. If the two positions are different by more than six NM, the CDU message INERTIAL/ORIGIN DISAGREE shows.
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777 AIRCRAFT MAINTENANCE MANUAL

ADIRS -ALIGNMENT

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ADIRS -ALIGNMENT -POS INIT CDU PAGE

General
To begin alignment, access the POS INIT page on the CDU. Thirty seconds after the ADIRU powers up, the POS INIT page shows box prompts under the SET INERTIAL POS. At this time you can line select an inertial position into the SET INERTIAL POS line. You can use one of these positions:
*
The inertial position you entered into the scratchpad

*
GPS position

*
Last position

*
Reference airport

*
Gate position.

To get the airport and gate position, line select the airport identifier and gate identifier into the appropriate line and the position shows on that line.
Enter Inertial Position
During alignment, the box prompts show until you enter an inertial position. If there is no entered inertial position when the ADIRU is ready to go into the NAV mode, the CDU shows the ENTER INERTIAL POS message.
As part of the alignment and when there is an entered inertial position, the ADIRU goes through an inertial position comparison test and the latitude comparison test. If both of the tests pass, the ADIRU can complete the alignment and go into the NAV mode. If either of the tests fail, the CDU shows box prompts and the ENTER INERTIAL POS message. Enter the same inertial position again and the ADIRU uses that position to complete alignment and goes into the NAV mode.
Alignment Reinitiated
If the alignment cannot finish due to airplane movement or an invalid inertial position entered twice, the CDU shows dashes and the ALIGNMENT REINITIATED message.
Auto Nav Realign Mode
Dash promts show during the auto nav realign (ANR) mode. The dashes tell that the ADIRU is ready to accept an inertial position. Also, the dashes tell that inertial input is optional.
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