If tower or surface visibility is below four statute miles, which will be reported in the METAR?

When tower or surface visibility is below four statute miles, the report will include the lesser of the two visibility measurements. This is important because visibility values are essential for pilots and air traffic control in assessing flight safety, and the lesser value provides a more accurate reflection of current conditions that could influence operational decisions.

In aviation reporting, particularly in METARs, the visibility reported is the most conservative measurement, which is crucial during conditions of reduced visibility, such as during fog, heavy precipitation, or other weather phenomena. By focusing on the lesser visibility, the METAR provides a true representation of what pilots can expect when approaching and landing at an airport.

In practical terms, the other options would not accurately reflect the necessary information required for safe flight operations. Reporting the maximum or average visibility could mislead pilots about the actual visibility they will encounter, which is why the focus is on the lowest value. This standard ensures that everyone using the METAR is aware of the most restrictive and potentially hazardous conditions.