Under what conditions would you perform an ADIRU/IR reset and what symptoms would prompt it?

• A. When attitude or heading data are unreliable or lost; perform resets per SOP to re-initialise the inertial reference system.
• B. When fuel imbalance occurs.
• C. When cabin pressure is high.
• D. When weather radar fails.

Answer: (A)

The important idea here is that the ADIRU/IRS provides the aircraft’s attitude and heading data, so you reset when that data becomes unreliable or disappears. A reset reinitialises the inertial reference system to clear temporary faults, drifts, or biases and restore accurate navigation information.

You’d trigger this when you observe attitude or heading data that doesn’t look right—attitude indicator or heading values that are erratic, jump around, or stop updating. If multiple IRS units disagree with each other, or you see inertial reference fault messages, that’s a strong sign the system needs reinitialisation. The reset is done following SOP, and often a fresh alignment is required after the reset to bring the system back to accurate navigation.

Other issues listed—fuel imbalance, high cabin pressure, or weather radar failure—aren’t related to the inertial reference data. They involve different systems and procedures, so they wouldn’t prompt an ADIRU/IR reset.