Trajectory Assessment Support for Air Traffic Control

Abstract

Future Air Traffic Management (ATM) systems may lead to a shift from the state based operation that is used today to a trajectory based operation where automation generates new trajectories to resolve conflicts and pilots can sent requests in the form of trajectories. If all aircraft participate in the trajectory based operation and all possible situations are taken into account, monitoring and re-planning the trajectories could be automated. However in the near future not all aircraft will be capable of trajectory based operations and it will be difficult to design an automated system that can cope with all situations. Furthermore a human will probably always remain responsible. As a consequence a controller in a (semi) trajectory based operation must be able to monitor the automation and in unforeseen situations come up with a solution. To be able to perform these tasks, the controller needs tools to asses the different trajectories to detect unforeseen unsafe situations and subsequently generate a solution. The paper describes an experiment to get data on the usability of current tools to asses a new trajectory and to explore the potential benefits of new tools that would make the separation margin more explicit. I. Introduction N earlier research, it has been shown that air traffic controllers can benefit from support tools when performing their conflict detection and resolution task 1,2,3 . The support tools used in this research vary from alerting the controller when a conflict is detected to automatically generating a conflict resolution. In the latter case the automation proposes a single maneuver to be executed by an aircraft to resolve the upcoming conflict 1 .The air traffic controller has to evaluate the new trajectory using his knowledge and experience before communicating the solution to the pilot. A similar process of trajectory evaluation is expected when in the future controllers will receive flightplan requests by pilots 2 . In this concept pilots use onboard systems to generate a conflict free path optimized for their flight and send it by datalink to air traffic control. The controller evaluates the requested trajectory and accepts, rejects or modifies the request. In Ref. 3, an experiment is described in which the trajectory negotiation process between pilot and controller was evaluated. It showed that when pilots requested a flight path change which was conflict-free according to the flight deck conflict detection and resolution system, controllers still rejected some of these trajectories. A possible explanation is that controllers use their own heuristics to assess whether a trajectory will be safe or not; as stated in Ref. 3, “…a ‘safe’ route by controller standards may require more than missing other aircraft by the minimum separation requirement”. This brings up the question whether the air traffic controllers reject conflict free trajectories because using their own heuristics they want to maintain a larger separation margin then strictly required or that the tools currently used will not give them the insight in the separation margins a new trajectory actually has.