ABSTRACT
Modern commercial air transportation revolves around airlines, airports and the air navigation service providers (ANSPs). 1 The latter, our focus here, are responsible for supplying a number of services; they not only control aircraft movements and separate planes on the ground and in flight, but also offer information on such things as weather conditions and communication facilities. They may be seen as providing and managing the links of the air transportation system with airports as the hubs and air corridors as the links.
