What is the fourth step when performing a train check once the train is "Standing"?

The correct choice of selecting "EXECUTE" as the fourth step when performing a train check once the train is "Standing" is crucial for ensuring that the subsequent actions based on the train status are processed correctly. After confirming that the train is stationary, selecting EXECUTE is an operational command that validates and initiates the next steps of the train check protocol. This step typically follows the initial actions, such as applying the brake valves or checking cut-out valves, ensuring that the system is prepared to continue testing and verifying function before proceeding with more involved tests, like the horn test or other checks. This structured approach helps maintain safety and proper procedure adherence across the operation, reflecting the importance of meticulous protocol in railway management.

In contrast, applying brake valves is an earlier step, and checking cut-out valves occurs before EXECUTE. Initiating the horn test is usually a later action performed after the system is confirmed operational through the selection of EXECUTE. Thus, selecting EXECUTE plays a pivotal role in the procedural flow of conducting a thorough and efficient train check.