In most countries, a flight may be operated for money only if it meets three criteria:
- the pilot must hold a valid commercial pilot's certificate
- the aircraft must hold a valid commercial registration
- the operator must hold a certificate or some other authorization for commercial operations
There are some exceptions — for example, a flight instructor is normally allowed to fly for money in a private aircraft owned by the student — but the above requirements hold for most flights where money changes hands.
Typically, a commercial certificate or registration requires higher standards than a private one. For example, a commercial pilot may have to demonstrate more maneuvers to a higher standard, and may need to pass more frequent medical examinations. A commercially registered plane may require more frequent or more extensive maintenance.
It is the purpose of the flight, not the type of aircraft or pilot, that determines whether the flight is commercial. For example, a two-seat Cessna 150 towing a banner for money would be a commercial flight, while a large jet flown by its owners for a private vacation would not be, even if the pilots were commercially certificated and the jet were commercially registered.
After World War II, commercial aviation grew rapidly, using mostly ex-military aircraft to transport people and cargo. This growth was accelerated by the glut of heavy and super-heavy bomber airframes like the B-29 and Lancaster that could be converted into commercial aircraft. The DC-3 also made for easier and longer commercial flights. The first commercial jet airliner to fly was the British de Havilland Comet. By 1952, the British state airline BOAC had introduced the Comet into scheduled service. While a technical achievement, the plane suffered a series of highly public failures, as the shape of the windows led to cracks due to metal fatigue. The fatigue was caused by cycles of pressurization and depressurization of the cabin, and eventually led to catastrophic failure of the plane's fuselage. By the time the problems were overcome, other jet airliner designs had already taken to the skies.
- Aviation and the environment (including effects on climate change)
- Direct flight
- Domestic flight
- International flight
- Non-stop flight
- Private aviation