Air Traffic Management (ATM) is a set of services which every State must provide for the safe and efficient operation of air traffic. Today, it is almost entirely financed by user fees according to the "user pays" principle. Until today, the "user" has always been assumed to be the airspace user, normally an airline. This system comes under pressure today: current Single European Sky (SES) regulation is built on the assumption that air traffic in Europe continuously increases. Thus, the financing of ATM would be secured by increasing revenue due to higher traffic volumes. Technological progress and efficiency gains should lead to reduced cost and lower environmental footprint of aviation while increasing safety and capacity. Two crises – the financial and banking crisis of 2008 and more recently the COVID-19 pandemic – show that the assumptions of this regulatory framework are wrong. Additionally, there is the question of who the actual "users" are. Does ATM only serve paying airlines or are there some services which are provided in the public interest? This issue of Network Industries Quarterly explores this last question by way of three original contributions.