This article examines the economic regulation of a hub European airport and the relationship system between actors involved in, or subjected to, this regulation. Studying the case of Aéroports de Paris, it is argued that airport economic regulation is produced by the strong conjunction of interests between the hub airport's operator, the dominant airline, and public authorities. These three categories of actors form an "iron triangle" framing and shaping the terms of economic regulation to satisfy their interests, and the shift from a cost-plus to a price-cap regulation does not dramatically threaten the maintenance of the triangle. All other actors (nondominant, domestic airlines, and international air carriers) are excluded from the iron triangle even if they remain deeply affected by its decisions. Finally, this article calls for an analytical generalization of this theorization for semiprivatized European hub airports.