How should the failed on-board PTC apparatus be treated until it is repaired?

The appropriate approach to handling a failed on-board PTC (Positive Train Control) apparatus is to treat it as inoperative. This is critical for ensuring the safety and reliability of train operations. When a PTC system fails, it may no longer be able to effectively monitor and control train movements, which are essential functions designed to prevent accidents and ensure safe distances between trains.

By categorizing the failed apparatus as inoperative, it establishes a clear protocol for immediate action. This designation ensures that proper measures are taken to address the failure, prompting repairs or alternative safety measures necessary to maintain safe train operations. Recognizing a malfunction in this manner helps prioritize repairs and enhances overall safety protocols, as trains cannot rely on a system that is not functioning properly.

In contrast, treating it as operational until verification or as ineffective but usable could lead to dangerous situations where operators might mistakenly assume that the system can still provide the necessary safeguards. Declaring it a low priority issue would undermine the urgency required in addressing potential safety hazards related to train operations. Thus, treating the failed on-board PTC apparatus as inoperative is the best practice to ensure safety on the rail network.