Definition
An aircraft assembled by an individual builder either from a manufacturer-supplied kit of pre-fabricated parts or from a set of construction plans, with the builder sourcing materials and fabricating components themselves. In the United States, these aircraft are typically certificated in the Experimental category as Amateur-Built, which requires that the major portion of the aircraft be constructed by the builder for their own education or recreation.
Plain English
An aircraft built at home by the owner, either from a packaged kit of parts or from drawings, rather than purchased fully assembled from a factory.
Context Anchor
Seen in light-sport and experimental aircraft discussions, especially when comparing factory-built aircraft with aircraft built by individual owners.
Derivation
‘Kit’ refers to a packaged set of parts ready for assembly, the same sense used for model kits or furniture kits. ‘Plans-built’ means built from plans — the technical drawings and instructions — with the builder acquiring or fabricating the parts themselves. The two terms describe two ends of the same do-it-yourself building approach.
Why Pilots Care
Kit and plans-built aircraft fall under different certification rules than factory-built airplanes. They carry operating limitations, may have restrictions on carrying passengers for hire, and the pilot or owner needs to understand the aircraft’s certification category before flying it.
Intuition Check
Do not assume “kit” means toy-like, simple, or unfinished. In this context, a kit or plans-built aircraft can be a real, flyable aircraft, but it is approved and documented differently from a fully factory-built airplane.
Example Sentence 1
Many light-sport aircraft on the field are kit or plans-built aircraft completed by their owners over several years.
Example Sentence 2
A pilot must complete all required inspections before flying a kit or plans-built aircraft for the first time.