What is the first action to take when a navigation sensor gives an invalid reading?

When a navigation sensor provides an invalid reading, the first action should be to check the sensor's configuration. This step is crucial because the issue may arise from incorrect settings, calibration errors, or connectivity problems. By assessing the configuration, you can ensure that the sensor is operating correctly and receiving accurate input, which is essential for reliable navigation.

Taking this action allows you to identify and rectify any issues that are under your control before proceeding to more drastic measures such as restarting the system or changing display settings. This methodical approach prioritizes troubleshooting the source of the problem, ensuring that any subsequent actions taken are informed and necessary.

In contrast, changing the chart display might not address the underlying issue of the invalid reading, and restarting the navigation system could temporarily fix the issue but might not identify the root cause. Ignoring the reading is unsafe and can lead to navigation errors, putting the vessel at risk. Therefore, checking the sensor's configuration is the most logical and effective first step.