What should a train crew do after experiencing a speed failure under Rule 409?

In the context of Rule 409, the appropriate action for a train crew experiencing a speed failure is to cut out the Automatic Speed Control (ASC) and report the situation as soon as possible, typically to the designated dispatcher or control center as indicated in Rule 204. This response is crucial because it ensures that the safety mechanisms are disengaged when they are no longer functioning correctly, allowing for safer operational management of the train.

Cutting out the ASC is essential to prevent unintended speed regulation issues while maintaining the ability to control the train effectively in the current operating situation. By promptly reporting the failure, the train crew ensures that proper measures can be taken by supervisory personnel to assess the situation, evaluate the safety of continuing the journey, and arrange for any necessary repairs or checks.

The other responses do not reflect the safety priorities outlined in operating standards. For example, waiting for a supervisor could delay critical actions that may be necessary to ensure safety. Increasing speed cautiously without addressing the failure would compromise safety protocols. Lastly, proceeding without restrictions undermines the entire purpose of having operational rules to manage equipment failures.