What should a train operator do if the indication light goes dark on a regular passenger train in motion?

When the indication light goes dark on a regular passenger train in motion, the appropriate action is to stop and immediately investigate. This response is critical because the dark indication light may signify a malfunction or an issue that could compromise the safe operation of the train.

Stopping the train allows the operator to assess the situation more carefully, ensuring the safety of passengers and crew. Investigating the cause of the dark light can help identify any problems with the train's systems or signals that could affect performance or safety. This proactive measure is essential in maintaining the operational integrity of the train and ensuring that any necessary repairs or adjustments can be made before continuing the journey.

In contrast, continuing to operate as usual without investigating can lead to serious safety risks if there is an underlying issue that needs attention. Reporting it to the control center is also important but should follow the initial assessment and investigation on-site. Adjusting the controller handle may not address the root cause of the issue indicated by the dark light, making it an inadequate response in this scenario.