Which document is required to demonstrate the aircraft's ability to operate safely?

The Certificate of Airworthiness is the document required to demonstrate the aircraft's ability to operate safely. This certificate confirms that the aircraft meets all safety standards and regulatory requirements established by aviation authorities. It ensures that the aircraft has been properly inspected, maintained, and is airworthy, thus certifying that it can perform its intended functions without posing a risk to safety.

The Radio License pertains specifically to the communication equipment aboard the aircraft, ensuring that it can operate within the regulations of air traffic control. The Pilot Operating Handbook is essential for providing operational data about the aircraft, including performance specifications, but does not certify the aircraft's airworthiness. The Journey Log Book is useful for keeping track of flight hours and maintenance, but it does not provide any certification of the aircraft's ability to operate safely. Thus, the Certificate of Airworthiness is the critical document confirming safety compliance for the aircraft's operation.