What is a critical first step when entering ATC Bypass mode?

The critical first step when entering ATC Bypass mode is to ensure that the train has stopped. This step is vital for safety and operational integrity. When a train is in ATC Bypass mode, it means that the automatic train control system has been disabled, and the engineer must take full manual control of the train's operations. Before doing so, it is essential that the train is at a complete stop to prevent any unintentional movement that could lead to accidents or unsafe situations.

By ensuring the train is stopped, the engineer can then safely transition to manual control or execute the necessary procedures to activate the ATC Bypass mode. This consideration for safety first helps maintain control over the train and ensures that the engineer can operate it effectively without any external influences or momentum that could complicate the transition to manual operations.