In many countries, great attention is devoted to the development of regional airports, both to face the congestion situation at the main hubs and to help the economic development of some decentralized areas. In this context many actors can play an important role, such as airport planners, air companies (including low-cost companies) and users (passengers and/or freight), in producing important demand levels at airports thanks to their travel choices. More studies all over the world concern the analysis of airport systems in order to verify the role of each airport and the effects on the main, congested hub(s). Particularly, an efficient use of resources suggests considering the role of existing, regional airports