A light-sport aircraft (LSA), or light sports aircraft, is a small aircraft that is simple to fly and that meets certain regulations set by a national aviation authority restricting weight and performance. For example, in Australia the Civil Aviation Safety Authority defines a light-sport aircraft as a heavier-than-air or lighter-than-air craft, other than a helicopter, with a maximum gross takeoff weight of not more than 560 kilograms (1,230 lb) for lighter-than-air craft; 600 kilograms (1,300 lb) for heavier-than-air craft not intended for operation on water; or 650 kilograms (1,430 lb) for aircraft intended for operation on water. It must have a maximum stall speed of 45 knots (83 km/h; 52 mph) in landing configuration; a maximum of two seats; there is no limit on maximum speed unless it is a glider, which is limited to Vne 135 kn CAS; fixed undercarriage (except for amphibious aircraft, which may have repositionable gear, and gliders, which may have retractable gear); an unpressurized cabin; and a single non-turbine engine driving a propeller if it is a powered aircraft.
In the United States, several distinct groups of aircraft may be flown as light-sport. Existing certificated aircraft and experimental, amateur-built aircraft that fall within the definition listed in 14CFR1.1 are acceptable, as are aircraft built to an industry consensus standard rather than FAA airworthiness requirements. The accepted consensus standard is defined by ASTM International Technical Committee F37. Aircraft built to the consensus standard may be factory-built and sold with a special airworthiness certification (S-LSA) or may be assembled from a kit under the experimental rules (E-LSA) under experimental airworthiness. A company must have produced and certified at least one S-LSA in order to be permitted to sell E-LSA kits of the same model. E-LSA kits are not subject to the normal experimental amateur-built (E-AB) requirement 14 CFR 21.191 which identifies an aircraft, the "major portion of which has been fabricated and assembled by persons who undertook the construction project solely for their own education or recreation.