When observed visibility is between two reportable values, the visibility reported is the:

When observed visibility falls between two reportable values, the proper procedure is to report the lower of the two values. This method ensures a conservative reporting standard that is important for pilots and others who rely on visibility data for safety and operational decisions.

By reporting the lower value, it provides a more cautious assessment of conditions, which is crucial in aviation where safety margins are paramount. Pilots, for instance, often use visibility information to determine whether it is safe to take off or land, so a lower value helps mitigate the risk of overestimating the flight conditions. Reporting higher values or averages could lead to unsafe situations if visibility conditions worsen unexpectedly.

This practice aligns with aviation standards and ensures that the data provided reflect the most conservative estimate of visibility available at any given moment.