In aviation, airworthiness is the measure of an aircraft's suitability for safe flight. Initial airworthiness is demonstrated by a certificate of airworthiness issued by the civil aviation authority in the state in which the aircraft is registered, and continuing airworthiness is achieved by performing the required maintenance actions.

Certification is based on standards applied by civil aviation authorities. Interoperability is served when national benchmarks adopt standards from international civil and military organizations such as International Civil Aviation Organization (ICAO), European Aviation Safety Agency (EASA), NATO and European Defence Agency (EDA).

In the U.S., Title 14, Code of Federal Regulations, Subchapter F, Part 91.7 states: "a) No person may operate an aircraft unless it is in an airworthy condition. b) The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for safe flight. The pilot in command shall discontinue the flight when unairworthy mechanical, electrical, or structural conditions occur which compromise the airworthiness."

One airworthiness regulation is found in ICAO international standard of Annex 8 to Chicago Convention on International Civil Aviation which defines "airworthy" - in respect of an aircraft, engine, propeller or part there of - as "The status of an aircraft, engine, propeller or part when it conforms to its approved design and is in a condition for safe operation". The application of airworthiness defines the condition of an aircraft and its suitability for flight, in that it has been designed with engineering rigor, constructed, maintained and is expected to be operated to approved standards and limitations, by competent and approved individuals, who are acting as members of an approved organization and whose work is both certified as correct and accepted on behalf of the state of aircraft registry.

Apart from this organization, there are other ones like Federal Aviation Administration (FAA) or EASA that establish their own rules. In the case of the FAA, the regulation of airworthiness is found in Title 14 in the collected Code of Federal Regulations. The EASA specifications are found in several regulations: as nº 216/2008 (Basic Regulations), nº 748/2012 (Initial Airworthiness), nº 2015/640 (Additional specifications about airworthiness) and nº 1321/2014 (Continuing airworthiness).

In the regulation (UE) nº216/2008, common rules in the aviation sector are established and created the European Aviation Safety Agency. Article 5 of this regulation details the first specifications about airworthiness. Article 20 is about airworthy certification.

The main objective of these rules are to establish and to maintain a high and uniform security level at the civil aviation in Europe. For that reason, it lays down different rules according to the airworthiness:

The Regulation (EU) No. 748/2012 establishes the dispositions of application on the airworthiness and environmental certification of aircraft and related products, components and equipment, as well as the certification of design and production organizations.