Which document must be carried on board for every flight?

The correct answer is that the Journey Logbook must be carried on board for every flight. This document is essential as it provides a record of the aircraft's operational history, including flight times, maintenance information, and any discrepancies noted during previous flights. This log is crucial for ensuring that all maintenance requirements are met, as it helps pilots track compliance with mandatory inspections and repairs, thus supporting safe operation.

While other documents, such as the Certificate of Registration and the Airworthiness Certificate, are important for the legal operation of the aircraft, they do not need to be on board for each flight. The Airworthiness Certificate, for instance, should be available and validated, but as long as it is on file and the aircraft is in compliance, it does not have to be physically carried. The Technical Logbook contains detailed technical and maintenance records; however, it is not mandatory for pilots to carry it during each flight. In contrast, the Journey Logbook is a practical tool that pilots use actively for flight operations and must be on hand to document any significant happenings or changes during flight.