Which instrument provides backup attitude information and can operate for at least three minutes on total loss of power?

• A. Inertial Navigation System (INS)
• B. Global Positioning System (GPS)
• C. Intercommunication Audio System (IAS)
• D. Attitude Reference Indicator (ARI)

Answer: (D)

When primary attitude information is lost, a reliable backup that can keep showing pitch and bank is essential. The Attitude Reference Indicator is exactly that standby attitude instrument. It’s designed to operate on its own independent power source, so it can provide attitude information for at least three minutes after total loss of aircraft power. This gives the pilot a dependable reference to maintain control and reestablish normal flight as systems come back up.

The other options don’t fit because they either require power to function or don’t provide attitude data: an inertial navigation system usually depends on power and wouldn’t maintain attitude after a complete power loss; GPS gives position information, not attitude; and the intercommunication audio system handles communications, not flight attitude.