Air Freedom Rights | The Geography of Transport Systems
Freedoms of the air are not automatically granted to an airline as a right; they are privileges that have to be negotiated and can be the object of political pressures. All freedoms beyond the First and the Second have to be negotiated by bilateral agreements, such as the 1946 agreement between the United States and the UK, which permitted limited “fifth freedom” rights.
Source: Air Freedom Rights | The Geography of Transport Systems