Which unit is used for measuring visibility in aviation?

In aviation, visibility is primarily measured in statute miles. This measurement is commonly used in the United States and is part of the aviation weather reporting standards. When pilots receive weather reports or flight information, visibility provided in statute miles enables them to assess weather conditions relevant to flight operations, including potential obstructions such as fog or rain that could affect their journey.

Other measurement units mentioned, such as knots, are used for speed; kilometers are used in some regions for general distance but are not the standard in aviation visibility reports in the U.S.; and feet is commonly used for measuring altitude and elevation, not visibility. Therefore, statute miles is the correct unit for visibility assessment in aviation contexts.