Plain English Meaning

The shortest distance you must be able to see ahead in order to legally fly using your eyes alone, without relying on instruments. If you can't see at least that far, you're not allowed to fly under VFR.

Full Definition

The minimum flight visibility required by regulation for a pilot to legally operate an aircraft under Visual Flight Rules. The exact value depends on altitude, airspace class, and time of day, and is set out in 14 CFR Part 91.155.

Context Anchor

Seen in weather minimums, airspace rules, and preflight planning when deciding whether a flight may be conducted under Visual Flight Rules.

Derivation

VFR stands for Visual Flight Rules — the set of rules for flying by . ' minimum' simply means the lowest visibility allowed. The phrase exists because the rules set a floor below which flying is no longer considered safe or legal.