What indicates the loss of MAL during train operation?

The correct indication of the loss of the Minimum Action Level (MAL) during train operation is shown by the red signal on the dashboard. This signal acts as a visual cue for the train operator, alerting them that the operating conditions have deteriorated to a level where maintaining safe train control is at risk. The red signal is critical for safety management, as it prompts immediate attention and action from the operator to assess and address the situation.

While other options might suggest a malfunction or issue, the red signal is specifically designed as an immediate, clear indication of loss related to MAL. It is standardized across many systems to ensure that operators can quickly identify the loss of safe operational limits. This kind of visual alert is fundamental in signaling systems for trains, as it serves as a direct and unambiguous communication of critical safety information to the operator.