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Five transition strategies for sectorless ATM

In contrast to the traditional approach to air traffic management (ATM), which divides the airspace into sectors, sectorless air traffic management regards the airspace as a single unit. Instead of sectors, air traffic controllers are assigned several aircraft, which might not be in the same geographic region. Controllers are responsible for the assigned aircraft during their entire flight through the airspace from entry to exit. In previous papers we have detailed the sectorless ATM concept and shown that it is operationally feasible. One remaining question, however, is how to introduce the concept into operation. It is highly unlikely that sectorless ATM will be introduced for the entire airspace over a country, let alone a continent, in one step; a gradual introduction of the new concept limits the safety risks connected with new systems. Therefore, the concept will have to coexist with other ATM concepts. This discussion paper presents five different strategies for the introduction of sectorless ATM, namely element-wise, aircraft-wise, time-restricted, area-restricted, and top-down transition strategies. For each of these strategies we discuss advantages and disadvantages. In addition, we investigate the possibility of combining several strategies. In conclusion, we suggest a top-down transition strategy combined with an element-wise transition. This combined strategy limits the number of simultaneous changes but still takes full advantage of long-term planning. Furthermore, the number of controllers who have to be trained for the sectorless concept can be estimated quite accurately from the flight plans.