What is indicated by the ARM NOW message on the HTD?

The ARM NOW message on the HTD (Hand Held Terminal Display) indicates that the system is fully armed. This means that the air brake system is ready and functioning properly, allowing the train crew to operate the brakes as intended. When this message appears, it serves as confirmation that all necessary safety and operational checks have been completed, and the system is prepared for use.

Understanding that the presence of the ARM NOW message confirms the system's readiness is crucial for safe train operations. If the system were not fully armed, the crew would not receive this message, signaling that they need to take corrective action or perform additional checks before proceeding.