Filling En-Route Airspace - Where are the Limits?

The paper describes an optimistic traffic forecast for the year 2050, leading to a traffic volume 2.5 times as high as 2019. The focus of this paper is en-route traffic above FL150 and in particular, if the en-route part of almost 310 000 flights can be handled in a safe and efficient way. It is shown how the initial traffic demand needs to be adapted to reach a scenario free of conflicts and how much flights need to divert from their originally optimum path