IFATS: 4D contracts in 4D airspace

Abstract

The perspective that is considered in the European Innovative Future Air Transport System (IFATS) project opens new ways for the management of the overall air transport system (ATS). In this project, the IFATS consortium decided to use a methodology providing a large and open thinking space in order to imagine and propose new long term solutions to pioneer the air transport of the future. The basic feature of the IFATS concept is to go as far as possible in the ATS automation. The approach that has been taken is purely technical: thus, the concept that has been defined is a “techn ically possible” extremely automated system and not necessarily a “likely to happen” sys tem. The project started with identifying and analysing the technical issues of the automatio n of the ATS functions, and then it came to the validation of the resulting innovative ATS t hrough safety analysis and simulations. This concept has enabled the consortium to think “o ut of the box” and to introduce a cornerstone of the IFATS concept: 4D contracts in a 4D airspace. The 4D trajectory concept (being at a given geographical position at a given time) is already existing and studied, but its main drawback is that the compliance of the real 4D trajectory with the planned one has to be constantly monitored by ATC. Indeed, the 4D trajectory may vary due to meteorological conditions, for example. Additionally, whoever is i n charge of trying to keep the aircraft on the planned 4D trajectory, the pilot or the control ler, the task is hard to achieve. The aircraft automation brings a part of the solution with the 4 D FMS. Then, the question of who will be in charge of maintaining separation has to be answered. The IFATS concept is straight forward on this issue. First, the ground segment of the system (the Air Transport Management System), which is also automated, is in charge of the generation of conflict-free 4D trajectories according to the demand and to the airspace capacity. Then, aircraft are given 4D contracts ; they are in charge of monitoring their own compliance with the contract, which means staying inside their assigned 4D volume , or to ask for a new contract if they cannot. In doing so, they have the guarantee to fly conflict-free trajectories. Of course, the main difficulty lies in the generation of those con flict-free trajectories. To ease this generation, the four dimensions of the airspace are fully used without the current constraints linked to procedures, navigation waypoints and airways: 4D contracts are created and have to be respected in the very large four dimensions a irspace. The present situation of the IFATS project is that simulations prove that this e xtremely automated ATS where aircraft would be operating automatically, monitored by an automatic control supervised by ground operators, is a credible option. But further invest igations are needed to identify what could be a transition phase between the current ATS and s uch a disruptive concept.