Commercial aircraft, in common with all public transport, must be subjected to routine inspections and regularly overhauled in the interest of both safety and economy.

Aircraft maintenance and overhaul are not just the domestic concern of the organisation doing the work. There must be adherence to Standards approved by the Air Registration Board on behalf of the Ministry of Civil Aviation; and these Standards are the national interpretation of some of the directives issued by the International Civil Aviation Organisation as part of the international agreements regulating air safety. The regulations are neither rigid nor detailed, but they exist for the protection of air travellers against the remote chance of an operator failing to maintain airworthiness. In particular, they call for regular maintenance checks and, to procure annual reissue of the Certificate of Airworthiness, an annual overhaul or its equivalent.