Which document must a pilot carry while flying as required by the FAA?

A pilot is required to carry a valid pilot certificate and any necessary medical certificate while flying as mandated by FAA regulations. The pilot certificate serves as proof of the pilot's qualifications to operate an aircraft, while the medical certificate confirms that the pilot meets the necessary health standards to ensure safe flight operations.

These documents are crucial for a pilot to demonstrate their ability to safely navigate and manage an aircraft. The requirement to carry these certificates directly supports the safety and regulatory compliance of flight operations. In the context of aviation safety, possessing a current and appropriate pilot certificate along with a valid medical certificate is essential for both the pilot and the passengers.

The other options involve documents that, while they may be important for various operational aspects or legal requirements, do not meet the specific FAA requirement for documentation that must be carried in the aircraft during flight.