Definition
The greatest horizontal distance at which prominent unlit objects can be seen and identified by day, and prominent lighted objects can be seen and identified by night, as determined by atmospheric conditions and reported in statute miles or fractions thereof.
Plain English
How far you can clearly see and recognize things through the air. It is reported as a distance — for example, 10 miles, 3 miles, or half a mile — based on how clear or hazy the atmosphere is.
Context Anchor
You will see visibility in aviation weather reports, preflight planning, airport observations, and decisions about whether conditions are good enough to fly visually.
Derivation
From Latin visibilis, 'able to be seen,' from videre, 'to see.' In aviation it is given a precise meaning: not just whether something can be seen, but the measured distance at which it can be identified.
Why Pilots Care
It sets the legal limits for VFR operations and directly affects the safety of takeoff, landing, and navigation decisions.
Grounding Statement
If haze, rain, fog, smoke, or darkness keeps you from identifying objects far away, the visibility is lower.
Intuition Check
Visibility does not mean simply “I can see outside.” In aviation, it means how far away you can see and identify the right kind of object under the current conditions.
Example Sentence 1
The METAR reported visibility of 3 statute miles in light rain, so the pilot reviewed the VFR weather minimums before departure.
Example Sentence 2
Fog reduced visibility to one mile, requiring the pilot to fly the ILS approach instead of a visual one.