What must be done if the seal on the ATC Bypass switch is missing?

The correct course of action when the seal on the ATC Bypass switch is found to be missing is to inform the trainmaster or yard foreman. This is a critical safety protocol, as the seal indicates that the bypass switch has not been tampered with or incorrectly maintained. Reporting the issue allows for appropriate steps to be taken to assess the situation, such as inspecting the switch or potentially replacing it if necessary.

By communicating this issue, proper safety measures can be established to ensure that the train's Automatic Train Control (ATC) system is functioning correctly and that there are no risks posed to operations or passenger safety. It's essential for maintaining operational integrity and safety standards that such discrepancies are reported rather than ignored, particularly as it could lead to unsafe operating conditions if not addressed.

The importance of this step cannot be overstated, as it ensures that any potential faults are investigated and rectified before further operations occur, contributing to overall safety on the rail network.