What action should be taken if the brake pressure gauge shows zero while the train is in operation?

When the brake pressure gauge indicates zero while the train is in operation, it signifies a critical loss of air pressure in the brake system, which can compromise the safety of the train and those on board. The correct response is to investigate for potential air leaks or malfunctions. This proactive approach is essential because a lack of brake pressure means that the braking system may not function properly, posing a serious risk during operation.

By checking for air leaks or system issues, the train crew can identify and address any problems before they lead to a complete brake failure. This might involve inspecting hoses, connections, and other components to ensure the integrity of the braking system, thereby maintaining safety standards and operational protocols.