Definition
An ATC classification system that groups aircraft by characteristics that affect the strength of the wake turbulence they produce, used to determine the separation distance and time intervals required between a leading and following aircraft. Categories are based primarily on maximum certificated takeoff weight, and in the ICAO/RECAT systems also on wingspan and approach speed. Common categories include Super, Heavy, Large, and Small.
Plain English
A way of sorting aircraft into groups based on how much disturbed air they leave behind them in flight. Controllers use these groups to decide how far apart aircraft must be so a smaller one isn't tossed around by a bigger one's wake.
Context Anchor
You may see this term in ATC procedures, wake turbulence discussions, airport operations, and FAA material explaining why different aircraft require different spacing.
Derivation
"Wake" comes from Old Norse vaka, meaning the track left behind a moving ship in water. Aviation borrowed the term because aircraft, like ships, leave a disturbed trail behind them — in this case, swirling air rather than water.
Why Pilots Care
Smaller aircraft following larger ones can lose control from the invisible swirling air trails, which is why specific spacing rules exist.
Analogy
It is like giving vehicles different splash zones on a wet road. A small car and a large truck both leave spray behind them, but the truck’s spray can affect others much more.
Intuition Check
Do not read “wake” as being awake or alert. Here, “wake” means the disturbed air left behind after an aircraft passes.
Example Sentence 1
Tower assigned a longer spacing interval behind the 777 because of its wake category.
Example Sentence 2
Controllers increased separation when a small trainer followed a heavy jet in the same arrival sequence.