Definition
In ICAO turbulence and wake turbulence categorization, an aircraft type classification applied to aircraft with a maximum certificated takeoff weight of 15,500 pounds (7,000 kg) or less. The classification is used by ATC to apply wake turbulence separation standards behind larger aircraft.
Plain English
A weight category for smaller aircraft. If an aircraft weighs 15,500 pounds or less at its certified maximum takeoff weight, it falls into the Light category for wake turbulence and separation purposes.
Context Anchor
Seen in ICAO flight plan information and air traffic control discussions about aircraft weight groups and spacing behind other aircraft.
Derivation
From everyday English 'light,' meaning 'not heavy.' Aviation borrowed the word as a simple weight label. The threshold (15,500 lb) is set by ICAO, not by the word itself.
Why Pilots Care
Controllers apply greater spacing behind heavier aircraft; misjudging your category can result in an encounter with strong wake turbulence.
Intuition Check
Light does not mean the aircraft has bright lights, and it is not just a casual way to say small. Here it is a formal aircraft weight category: 15,500 pounds or less approved maximum takeoff weight.
Example Sentence 1
Most general aviation training aircraft fall into the Light category for wake turbulence separation.
Example Sentence 2
Light aircraft are normally given standard radar separation unless following a large or heavy jet.