Which documents are required to be on board the aircraft at all times?

The correct answer is that the Aircraft Flight Manual (AFM) and both checklists must be on board the aircraft at all times. The AFM is a crucial document that provides important information regarding the operational limits and performance data of the aircraft. It serves as a reference for pilots to ensure the aircraft is operated within its prescribed limitations and guidelines.

Both checklists are also essential as they provide step-by-step procedures for various phases of flight, including pre-flight checks, normal operations, and emergency situations. Having these documents on board at all times supports operational safety and ensures that pilots can access critical information whenever needed.

While flight plans and navigation charts are important for flight operations, they can be updated and do not have to remain on board once the flight is over. Aircraft registration and airworthiness certificates must be accessible but may not necessarily need to be physically aboard the aircraft during each flight, depending on the regulations specific to the operation. The emergency procedures manual and maintenance log are important for safety and compliance, but they typically do not have the same mandatory presence in the cockpit as the AFM and checklists.