The effect of the Croatian Free Route Airspace implementation on the Air Traffic Complexity

It is well known that the increase in air traffic brings some negative connotations regarding delays, airspace capacity, air traffic controller workload, etc. To mitigate those problems, the European Commission has issued a development plan through the Single European Sky initiative, which yields a dozen solutions through the Single European Sky Air Traffic Management Research Joint Undertaking. Some of which is Free Route Airspace which enables aircraft operators to fly and plan direct routes through the airspace. Since this solution changes the way that the aircraft flies through airspace, different and new airspace routes have emerged. In this paper, the authors used fast time simulations with the PRU complexity model to observe how air traffic complexity was affected through Free Route Airspace implementation. It was observed that the increase in occupancy followed the increase in air traffic complexity, but not all results could be explained through the increase in the occupancy count. Also, to verify suspected claims the pre-FRA traffic from the 2016 was run on the FRA airspace and the reduction of complexity was observed. The authors concluded that the Free Route Airspace helped reduce the overall air traffic complexity, but further research and validation are still needed to concisely confirm those claims.