What must each crew maintain in the cab of the controlling locomotive?

Each crew must maintain a written or electronic record in the cab of the controlling locomotive to ensure effective communication and adherence to safety protocols. This record serves as a vital log that documents various operational details throughout the journey, such as inspections, locomotive performance, and any disturbances or incidents that occur during the trip. Maintaining such a record is crucial for accountability, operational awareness, and for regulatory compliance.

While other items might be important for specific functions, they do not serve the broad purpose of tracking operations or ensuring safety in the way that a written or electronic record does. For instance, a stop watch or train position map may assist in specific tasks but do not encompass the overall documentation needs required for crew operations. Status of crew breaks is also important but doesn't replace the comprehensive logging function provided by a written or electronic record.