What must be confirmed by the train engineer regarding the train length?

The train engineer must confirm the length reported by the PA-5 rolling stock because this information is essential for safe train operation. Knowing the exact length of the train allows the engineer to manage the train's movements accurately, ensuring safe clearances at stations, crossings, and during stops. It also plays a crucial role in calculating stopping distances and ensuring compliance with the capacity of tracks and platforms.

While the number of cars and weight of the train are important operational factors, the specific measurement of train length is a critical piece of data needed for immediate decisions during train operation. Additionally, although the type of cargo may have implications for loading and safety protocols, it does not directly relate to the physical length of the train, which is why confirming the length reported is vital for effective scope of control over the train's dimensions and navigation through the rail network.