Plain English Meaning

The lowest visibility and the smallest distances from clouds you are legally allowed to fly in when flying by looking outside. If conditions are worse than these numbers, you cannot fly VFR.

Full Definition

The minimum flight visibility and distance-from-cloud requirements established by 14 CFR 91.155 that a pilot must have in order to operate an aircraft under Visual Flight Rules in a given class of airspace. The required values vary by airspace class, altitude, and time of day, but the underlying purpose is constant: to ensure the pilot can see and avoid other aircraft and terrain by visual reference outside the .