When a working radio on an occupied locomotive fails, when can the train continue?

The correct answer reflects an important safety protocol in rail operations regarding communication failure on a locomotive. When a working radio on an occupied locomotive fails, the train can continue until the next calendar day inspection. This is crucial because it ensures that trains do not operate under unsafe conditions for extended periods.

The next calendar day inspection provides a defined timeframe during which the issue can be thoroughly addressed, ensuring that the equipment is maintained in a safe and operational state. It emphasizes the significance of regularly scheduled inspections as a safety measure for ongoing operations.

Communication is essential for the safety of the train crew and others, and this regulation helps ensure that trains do not continue indefinitely without proper oversight regarding equipment functionality. The other options imply less rigorous safety measures that do not align with standard operating procedures to address equipment failures.