Which of the following is NOT a requirement for VFR flights operating in controlled airspace?

Filing a flight plan is not a requirement for VFR flights operating in controlled airspace. While it is advisable for pilots to file a flight plan for safety reasons and to enhance search and rescue efforts, it is not mandated by regulations for VFR flights. Pilots can operate VFR in controlled airspace without a filed flight plan, as long as they maintain compliance with other regulations, such as communicating with air traffic control and adhering to visual flight rules.

In contrast, prior radio communication, maintaining visual flight rules, and obtaining ATC clearance are all essential for ensuring safe and orderly operations within controlled airspace. These requirements are designed to promote situational awareness among pilots and air traffic controllers, minimizing the risk of mid-air collisions and promoting efficient traffic management.