When will the E/WD page move down to the lower DU?

The E/WD (Engine/Warning Display) page moves down to the lower Display Unit (DU) when there is a failure of the upper DU or if it is manually switched off. This feature allows for the continuity of essential flight information on the lower DU, ensuring that critical data remains accessible to the flight crew, even if there is an issue with the upper display.

This design is important for safety, as it provides redundancy in the display of crucial information, allowing pilots to maintain situational awareness and respond effectively even in adverse conditions. If both DUs were active or if the lower DU is off or during a system check, the E/WD page would not automatically shift positions, as the system is designed to maintain function on the active displays.