I. Introduction
The European Air Transportation Network was significantly impacted by the COVID-19 pandemic, resulting in an unprecedented loss of flight connections. In an effort to control the spread of the virus, governments implemented travel restrictions which lead to a dramatic decline in passenger traffic. While the traffic in the EUROCONTROL region fell drastically in 2020, it has since rebounded, with 6.2 million flights recorded in 2021. This corresponds to roughly half of the air traffic observed in 2019 [1].