What defines Visual Flight Rules (VFR)?

Visual Flight Rules (VFR) are defined primarily by the requirement to operate under Visual Meteorological Conditions (VMC). VFR enables pilots to navigate and control the aircraft by visual reference to the ground and other landmarks, allowing them to see and avoid obstacles, other aircraft, and weather phenomena. This requirement emphasizes the importance of visibility and cloud clearance, which are critical for safe flight under VFR conditions. When the weather meets VMC criteria, pilots can operate without relying solely on instruments, making it essential for VFR flight.

Other options may present conditions related to flight regulations, but they do not accurately define VFR. For instance, the required altitude of above 18,000 feet is actually a characteristic of Instrument Flight Rules (IFR) operations rather than VFR. Furthermore, while a flight plan can be filed for VFR flights, it is not always mandatory to operate under VFR. Lastly, operating only at night contradicts the essence of VFR, as it can be conducted during both daylight and nighttime conditions, provided that visibility criteria are met.