Definition
A decrease in the distance at which a pilot can clearly see and identify prominent objects, caused by atmospheric phenomena such as fog, mist, haze, smoke, precipitation, blowing dust, or blowing snow. In instrument approach planning, the cause and expected duration of the reduction matter, because they affect whether reported visibility will meet the minimums required to begin or complete the approach.
Plain English
Conditions in the air that make it harder to see far. Things like fog, rain, snow, smoke, or haze cut down how far you can see ahead, and that affects whether you're legally allowed to fly the approach.
Context Anchor
Seen in instrument approach discussions, weather briefings, and approach decision-making when a pilot is judging whether the runway or runway lights will be visible before landing.
Derivation
Visibility comes from a Latin word meaning “to see.” Reduction comes from a Latin word meaning “to bring back or bring down.” Together, the phrase points to the seeing distance being brought down from normal.
Why Pilots Care
Determines whether the pilot can continue to a landing or must execute a missed approach.
Grounding Statement
A visibility reduction means the airplane may be correctly lined up with the runway, but the air between the airplane and runway is too unclear for the pilot to see it soon enough.
Intuition Check
Do not read visibility reduction as simply “bad weather” or “darkness.” It specifically means the distance the pilot can see outside has become shorter.
Example Sentence 1
The METAR showed visibility reduction down to one mile in mist, so the crew reviewed the approach minimums before continuing.
Example Sentence 2
Heavy rain caused visibility reduction that forced the crew to divert to the alternate airport.