Control

The ADIRU are controlled from the ADIRU panel on the left overhead, toward the rear.

The panel has buttons to switch on/off the Air Data and or Inertial Reference part of each ADIRU.

The knobs control the state of the ADIRU. In the Off position there is no data from that ADIRU. In the NAV position, the normal position, the ADIRU sends out all the air data and inertial data noted before. In the ATT position, the air data is the same, but only attitude and heading are sent from the inertial reference part.

The initialization of position, is performed using the MCDU. On the INIT A page after entering the TO/FROM airports or the Company route, the “Align IRS” prompt appears.

The Latitude and Longitude are initially set, in the MCDU, to the airport reference. However, the Latitude and Longitude values may be slewed to arrive at a price location to be sent to the ADIRU for alignment.

The Flight Preparation section describes in detail the alignment process of the ADIRU, from a cold start. However, there is a fast alignment that can be performed with a ADIRU that is has already been aligned. The flight crew must switch the ADIRU knobs to the OFF position and back to the NAV position within 5 seconds. Doing this causes a fast alignment of the ADIRU . Note that a delay of more than 5 seconds causes a full alignment again lasting approximately 10 minutes.

The IRU parameters may be observed via the MCDU data page. There are separate IRU pages for each ADIRU and a Position monitor page showing the 3 separate ADIRU computed aircraft positions.

ADIRU computed aircraft positions need to be checked at the end of a flight to monitor the accuracy of the ADIRU

The aircraft fast align should not be confused with he the A330 simulation quick start, where a fast align may be performed even for a cold start in order not to wait the 10 minutes This is a simulation fast align.