In terms of vertical visibility, what does MM003 in METAR indicate?

When interpreting the METAR code, MM003 specifically indicates the vertical visibility is 300 feet. This measurement is crucial for pilots as it provides information on how far one can see vertically, particularly in conditions where the horizon may not be visible, such as during overcast or foggy conditions.

The prefix 'MM' signifies that the visibility is being measured in feet, and the number following indicates the specific vertical distance. In this case, 003 translates to a vertical visibility of 300 feet. This information helps pilots assess their situation, especially regarding takeoff and landing capabilities when flying in low visibility scenarios.

Understanding vertical visibility is essential for flight safety, as it helps pilots make informed decisions during potential low-visibility conditions by providing insight into the atmosphere above the aircraft.