Which of the following documents is NOT required for flight?

The Pilot Operating Handbook (POH) is not a mandatory document for flight operations in the same way that the other items are required. While the POH is critical for understanding the aircraft's performance limitations, operational procedures, and emergency procedures, federal regulations do not specifically mandate that it must be on board for a flight. Instead, the Airworthiness Certificate confirms that the aircraft is compliant with safety and design regulations, registration verifies ownership and allows the aircraft to be legally operated, and a Radio License may be required if the aircraft is equipped with radio transmitting capabilities for legal operation. Therefore, while the POH is important for safe operation, it is not classified as a required document for legal flight under current regulations.