What is the consequence of a complete failure of the ATC carborne equipment?

In the event of a complete failure of the ATC (Automatic Train Control) carborne equipment, the correct course of action involves switching to Bypass mode. This mode allows the train to continue operation under controlled conditions despite the loss of ATC functionality. It enables the engineer to manage the train's speed and movement safely while adhering to certain operational protocols that ensure safety alongside train handling.

Bypass mode is crucial because it allows for continued operation in critical situations where halting the train immediately may not be feasible. It provides a controlled means to handle emergencies or failures without exacerbating potential hazards, particularly in scenarios where stopping abruptly could lead to safety risks for passengers or operations.

Other options present measures that may not align with operational protocols for managing ATC failures. The requirement to operate at very low speeds or stop the train immediately could create significant disruption and safety issues, especially in busy rail networks. Prioritizing signals over safety does not accurately reflect the train's operational safety priorities, which are designed to ensure that safety remains paramount even in failure situations.