Estimating Requirements and Costs of 4D ATM in High Density Terminal Areas

Abstract

A key element of future Air Traffic Management concepts like SESAR or NextGen is the stepwise introduction of the extensive use of 4D trajectories. Two of the expected areas of benefit are reduced lateral flight path lengths through direct flight routings and the application of near idle descent flight profiles from en-route flight level to landing. High density terminal areas of large international airports present a particular challenge to these concepts due to their traffic share on the one hand and the traffic complexity on the other hand. This paper presents an approach to estimate requirements and costs for applying 4D ATM in a high density Terminal Manoeuvring Area (TMA) in a specific example. The approach is starting from a scenario where trajectory uncertainty is completely eliminated and aircraft proceed along their pre-planned 4D trajectories exactly. This “ideal” scenario is called Utopia. Utopia is used to calculate the upper bound for improvements which theoretically could be obtained from using 4D ATM. The only constraints that must be met in Utopia are conflict free runway threshold times. Then Utopia is degraded sequentially by the introduction of additional constraints and parameter uncertainties. Examples for such degradations are the stepwise increase of separation requirements between trajectories within the TMA or TMA entry time deviations. To compensate the degradation effects measures have to be taken to fulfil the initial constraints of conflict free threshold times. Measures are e.g. level segments in profile, speed changes or lateral route extensions. The degraded scenarios are evaluated with regard to feasibility and compensation costs. The results give an indication on the range of the degradation which can be compensated by specific measures. Indicators used for scenario evaluation are lateral route lengths, normalized flight times, number of separation conflicts and model fuel consumption. A reference scenario based on today’s route structure in a high density TMA is used as a lower bound starting point for the calculation of possible improvements. Aircraft in this scenario follow standard instrument departures and standard arrival routes that include guidance along a trombone as seen in many high density approach patterns today. All scenarios are evaluated using the air traffic simulator TrafficSim. TrafficSim is designed to support the development and validation of pilot assistant systems dealing with airborne separation assurance systems and air traffic management tools. It is as well suitable as a “proof of concept simulation” for new ATM-concepts or operations. All aircraft in the scenarios under study are equipped with a flight management system (FMS) that is capable of meeting multiple time constraints in a 4D trajectory. The traffic example used is based on an actual busy day of real traffic at a major hub in Central Europe. Real traffic is considered as important to depict the spatial and temporal distribution of demand, the traffic mix and the relationships between arrival and departure peaks. The traffic example contains about 1400 arrivals and departures and is being used consistently over all scenarios under study. Thus a direct and fast comparison between scenario results is facilitated. First results of the Utopia approach under study give an indication on the relation between the expected benefits of advanced 4D application in high density TMAs and the requirements associated to such a concept. In addition, the scenario and evaluation method developed can be used as a testing environment for new concepts to organize high density TMA traffic using 4D trajectories.