What units are primarily used for measuring visibility in aviation?

In aviation, visibility is primarily measured in statute miles or meters. This standard is used because it provides a clear and consistent way to communicate how far a pilot can see, which is crucial for flight safety and navigation. Statute miles are commonly used in the United States, while meters are more prevalent in other parts of the world, particularly where the metric system is in use.

Using these units allows pilots and air traffic controllers to effectively evaluate weather conditions, especially in relation to landing and takeoff operations. Visibility measurements in statute miles or meters are critical for determining whether conditions are suitable for flight operations under Visual Flight Rules (VFR) or if Instrument Flight Rules (IFR) must be employed.

Other units, such as kilometers and nautical miles, may sometimes be referenced in certain contexts, but they are not standard for visibility reporting in aviation. Similarly, yards and inches are not practical for measuring visibility as they denote much smaller measurements, which would not provide an effective range for aviation operations.