Flight Preparation (ADIRU Alignment )

With the aircraft electrically powered, the initial position and alignment of the Inertial Reference Units ( part of the ADIRU) may take place. This alignment takes approximately 10 minutes, but all other cockpit preparations can be carried out whilst it is occurring.

Locate the ADIRU panel on the left hand side of the  overhead panels. There are 1 set of IRU lights, 1 set of IRU knobs and 1 set of Air Data buttons.

Press in the Air Data buttons to switch on the air data part of the ADIRU. This will provide air data information on the PFD.

The PFD and ND will initially show warning flags for the air data and attitude data. The MCDU will also display an “ALIGN IRU” message.

Select each IR knob to the NAV position. The fault lights and ON BAT light will illuminate momentarily and then extinguish. There after, the ADIRU will then be in align mode.

The align mode last for about 10 minutes. The remaining align time is shown on the EWD ( limited to 7 minutes).

During the alignment process the flight crew must enter the aircraft’s present position.

On the MCDU  press the INIT page key and observe the INIT page.  

The aircraft’s present position may be entered via this page, either using a company route or a City pair of airports (TO/FROM)

The  INIT page now allows the flight crew to slew the present position Latitude and Longitude and to send that data to the ADIRU via the “Align IRS” prompt.

When the ADIRU has aligned, the PFD and ND are fully populated with the ADIRU data. There are no more ADIRU red flags in view.

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