fitness to fly.

A term used to describe both the legal and mechanical status of an aircraft with regard to its readiness for flight.

Airworthiness is a term used to dictate whether an aircraft is worthy of safe flight. It is illegal in most countries to fly an aircraft without first obtaining an airworthiness certificate from the responsible government agency. The airworthiness usually must be maintained by a program of inspections by an authorized aircraft mechanic, typically performed annually, or after a fixed elapsed flight time, such as every 100 hours.