What does the DU Red X indicate in flight operations?

The DU Red X indicator specifically points to an Automatic Flight Control System (AFCS) failure or a related issue with the aircraft's avionics, which can include an AGM (Airborne Ground Mode) failure. When a Red X appears on the Display Unit (DU), it signifies that the system is not functioning correctly and requires immediate attention by the flight crew.

Understanding the context of the display alerts is crucial for pilots during operations. For example, a fuel system issue would typically be indicated by a different alert or warning specific to fuel system status, rather than a Red X. Similarly, navigation errors would generally produce distinct alerts that inform the flight crew of specific navigation system discrepancies. Engine malfunctions are identified via engine-specific parameters, typically through dedicated warnings relevant to engine performance or health, rather than a generalized Red X on the DU.

Therefore, the identification of a Red X as indicative of AGM failure is consistent with the aircraft's alerting protocols, ensuring that pilots can quickly recognize and address critical failures in flight operations.