The compass signal to the DDRMI is normally provided by ADIRU 1, but can be alternately provided by _________.

The compass signal to the DDRMI is normally provided by ADIRU 1, but can be alternately provided by _________.

• A. ADIRU 3
• B. ADIRU 2
• C. IRS 1
• D. GPS 2

Answer: (A)

The compass display (DDRMI) gets its heading from the ADIRU unit, which provides the aircraft’s inertial and magnetic reference data. There are three ADIRUs for redundancy, so if the primary source (ADIRU 1) becomes unavailable, the system can switch to another ADIRU to maintain a valid magnetic heading reference. The standby option is ADIRU 3, which is designed to take over as the alternate source for the DDRMI heading. ADIRU 2 is typically used for other parts of the AHRS/airspeed/altitude data path, not as the direct alternate for the DDRMI heading. IRS 1 supplies attitude/heading data in a different pathway, and GPS 2 does not provide the magnetic heading reference used by the DDRMI.

The compass display (DDRMI) gets its heading from the ADIRU unit, which provides the aircraft’s inertial and magnetic reference data. There are three ADIRUs for redundancy, so if the primary source (ADIRU 1) becomes unavailable, the system can switch to another ADIRU to maintain a valid magnetic heading reference. The standby option is ADIRU 3, which is designed to take over as the alternate source for the DDRMI heading. ADIRU 2 is typically used for other parts of the AHRS/airspeed/altitude data path, not as the direct alternate for the DDRMI heading. IRS 1 supplies attitude/heading data in a different pathway, and GPS 2 does not provide the magnetic heading reference used by the DDRMI.