What must be done if the Captain's ND shows a blank screen?

When the Captain's Navigation Display (ND) shows a blank screen, one of the first steps to troubleshoot the issue is to check for a failure of the Display Management Computer (DMC). The DMC is responsible for processing and distributing the information that is displayed on the NDs and other electronic displays in the cockpit. A malfunction in the DMC can lead to loss of information on the ND, resulting in the blank screen that the pilot is observing.

By verifying the DMC’s functionality, the crew can determine whether the issue lies with the DMC itself or if there is another underlying problem affecting the display. This step is essential in identifying the root cause of the failure in order to take appropriate corrective actions, which may involve switching displays or resetting systems if necessary.

The other options do not directly address the specific cause of a blank ND. For example, switching to the First Officer's ND may not solve the underlying problem if the DMC is at fault. Similarly, checking RMP settings or resetting the Flight Management and Guidance Computer (FMGC) may not resolve display issues that are strictly related to the DMC's operation. Therefore, diagnosing a potential DMC failure is the most logical and effective first step in handling this situation.