How do airlines react to airport congestion? The role of networks

•We study the relationship between airline networks and airport congestion.•Network airlines keep frequencies high even if this increases congestion.•This results accounts for the higher percentage of delayed flights at hubs.•We predict a reinforcement of the existing hubs over time.•Policies promoting direct connections away from hubs may be socially beneficial.

In this paper, we investigate the relationship between airline network structure and airport congestion. More specifically, we study the ways in which airlines adjust frequencies to delays (as a measure of airport congestion) depending on the network type they operate. Our results suggest that network structure has a fundamental impact. Thus, while airlines operating fully-connected configurations reduce frequencies in response to more frequent delays, airlines operating hub-and-spoke structures increase frequencies. Therefore, network airlines have incentives to keep frequencies high even if this is at the expense of a greater congestion at their hub airports. This result sheds light on previously unclear results in the literature.