Bettina Birkmeier

Sectorless ATM and advanced SESAR concepts: Complement not contradiction

With SESAR (Single European Sky ATM Research) there is a program well on the way to developing and implementing advanced ATM (Air Traffic Management) concepts. Beyond the scope of the SESAR programme in the LRM2020 project there are investigations on sectorless ATM taking place, which would mean not an evolution but a revolution of current ATM. This discussion paper argues that sectorless ATM can not only be integrated and exploited within the SESAR innovations framework but also continues SESARs shift towards a more aircraft-centered view. The paper elaborates on the possibilities of bringing together the two concepts and thus conjointly meeting the goals of SESAR and mastering the challenges of future ATM.

First results on flight rules and conflict avoidance maneuvers for a sectorless ATM concept

The idea of sectorless ATM (Air Traffic Management) envisages the airspace as a whole instead of dividing it into sectors. The dismissal of sectors, however, necessitates the definition of a complete and unambiguous set of flight rules in order to regulate which aircraft has to introduce an avoidance maneuver in case of a conflict. This paper describes the research on flight rules conducted within DLRs research project on sectorless ATM and describes the developed rule set in detail. Since in a sectorless concept only one specified aircraft amongst the ones in conflict is responsible for the conflict resolution different kinds of avoidance maneuvers than nowadays are necessary. This paper specifies the avoidance maneuvers that have been developed for automatic conflict resolution by DLRs traffic simulator. In particular, vertical conflict resolution often combines horizontal and vertical avoidance to allow for inaccuracies of the vertical movement and trajectory prediction. The conflict resolutions are also offered as suggestions to the controller, who can either choose one of them or develop his or her own solution. It is debated why for short and medium-term conflict resolutions the automatically generated solutions might seem more sensible or efficient than for long-term conflict resolutions. It is explained that in long-term situations the system can be able to analyze situations more thoroughly than the controller. The discussion elaborates on possibilities to implement and apply these findings in a sectorless ATM concept.

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.

Safety net for a sectorless air traffic management concept

Today air traffic management divides the airspace into sectors. Controllers are responsible for one of these sectors and all the air traffic within. In a sectorless air traffic management concept the airspace is no longer divided into sectors but regarded as one piece. Controllers are assigned individual aircraft which they are responsible for from their entry into the airspace to their exit. This implies that the controllers have to manage flights which are not in the same geographic region but can be anywhere in the airspace and hence also in different traffic situations. Such a change of concept influences the way controllers work and calls for different support tools. Naturally, the question of safety arises with regard to standard operations as well as special situations. This discussion paper investigates the different safety aspects relevant in a sectorless concept. It highlights the differences between a conventional sectored and the proposed sectorless approach. We argue that most elements of the current safety net in air traffic management can also be applied to a sectorless air traffic management concept. Additional safety net elements are proposed together with examples of their application.

Controller team possibilities for sectorless air traffic management

Sectorless air traffic management is an en-route concept, which eliminates the need for control sectors. Instead of assigning a geographic area (sector), air traffic controllers are assigned certain aircraft. Controllers are responsible for their assigned aircraft all the way from entry to exit. In previous simulations, one controller was responsible for six aircraft at the same time. As these aircraft can be located anywhere in the sectorless airspace, controllers were provided with one traffic display for each assigned aircraft. This discussion paper suggests other possibilities for providing traffic information to sectorless air traffic controllers. Instead of having one traffic display for each aircraft under control (tiled display), controllers could work with a general map, a zoom display to magnify certain traffic situations, or a combination of such displays. We revisit the concept of controller teams and explore alternatives. In addition to working alone or in pairs of executive and controller, the sectorless air traffic management concept opens possibilities for innovative teamwork. For example, there could be a team of one coordinator and several executives, or even a control-room team. This paper gives examples of new display and team ideas and discusses their respective advantages and disadvantages. We argue that the way traffic information is displayed to controllers affects their mental models and working methods. In addition, we provide results on the tiled display from previous simulations and introduce ideas for future research.

Color schemes for a sectorless ATM controller working position

In sectorless air traffic management (ATM) concept, air traffic controllers are no longer in charge of a certain sector. Instead, the sectorless airspace is considered as a single unit and controllers are assigned certain aircraft, which might be located anywhere in the sectorless airspace. The air traffic controllers are responsible for these geographically independent aircraft all the way from their entry into the airspace to the exit. In order to support the controllers with this task, they are provided with one radar display for each assigned aircraft. This means, only one aircraft on each of these radar displays is under their control as the surrounding traffic is under control of other controllers. Each air traffic controller has to keep track of several traffic situations at the same time. In order to optimally support controllers with this task, a color-coding of the information is necessary. For example, the aircraft under control can be distinguished from the surrounding traffic by displaying them in a certain color. Furthermore, conflict detection and resolution information can be color-coded, such that it is straightforward which controller is in charge of solving a conflict. We conducted a human-in-the-loop simulation in order to compare different color schemes for a sectorless ATM controller working position. Three different color schemes were tested: a positive contrast polarity scheme that follows the current look of the P1/VAFORIT (P1/very advanced flight-data processing operational requirement implementation) display used by the German air navigation service provider DFS in the Karlsruhe upper airspace control center, a newly designed negative contrast polarity color scheme and a modified positive contrast polarity scheme. An analysis of the collected data showed no significant evidence for an impact of the color schemes on controller task performance. However, results suggest that a positive contrast polarity should be preferred and that the newly designed positive contrast polarity color scheme has advantages over the P1/VAFORIT color scheme when used for sectorless ATM.