OPTIMIZED SECTORIZATION OF AIRSPACE WITH CONSTRAINTS

In this paper we consider the Optimized Airspace Sectorization Problem (ASP) with constraints in which a given airspace is to be partitioned into a number of sectors. The objective of ASP is to minimize the coordination workload between adjacent sectors. We proposed a constraint programming approach to optimize the sectorization that shall satisfy all specific constraints e.g. the controllers’ workload is balanced among the sectors, the sectors are not fragmented, aircraft can not enter twice the same sector; aircraft cannot stay less than a given amount of time in each sector crossed, sectors cannot be fragmented etc. Introduction Sectorization is a fundamental architectural feature of the Air Traffic Control (ATC) system. The airspace is divided into a number of sectors, each of them is assigned to a team of controllers (Control Positions). Controllers of a given sector have (1) to monitor the flights, (2) to avoid conflicts between aircraft and (3) to exchange information with adjacent sectors where aircraft have planned to go. These tasks induce a workload which is often decomposed into three corresponding parts [1, 2, 3]: • The monitoring workload (MW) comes from the cyclic checking of aircraft trajectories. • The conflict workload (CW) results from resolution and avoidance of conflicts between aircraft. • The coordination workload (OW) is basically related to the exchanges that have to be performed between controllers of adjacent sectors and pilots of aircraft that are crossing through. But the air traffic changes over the day. This often leads to workload imbalance between the sectors. Furthermore, it is desirable that there are more the sectors (then more control positions) in the dense traffic periods of the day than the weak periods. Hence a tool to “dynamically” re-sectorize the airspace (more precisely a part of airspace – e.g. the sectors of a Air Traffic Control Center) is required to cope with the evolution of the traffic. When the sectors are designed, not only the balance constraint must be hold (in term of workload), but also that several following specific constraints have to be taken into account: • Convexity constraint. The same aircraft can not enter twice the same sector. It is not sensible, but it happened in the past, e.g. national boundaries in European airspace. For instance, the following case in the Figure 1 is not admissible:

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