Four-Dimensional Trajectory Based Air Traffic Management

Abstract

The Air Traffic Management environment emerging in Europe will make heavy use of a time-based architecture managing shared 4D trajectories generated by aircraft Flight Management Systems (FMS). The overarching objective is to improve the efficiency of air transport from check-in to check-out. This will be accomplished via a controllable flow established in a collaborative manner between the involved parties. The outcome is an improved and more efficient use of infrastructure and personnel, resulting in less environmental load and improved economy for each stakeholder. This heavily integrated air/ground system will require compatible bandwidth data link capabilities for maintaining the common data base (and thus common understanding) for traffic management and control. The implementation has a number of prerequisites. Any renegotiation of a previously agreed trajectory shall always result in a new 4D trajectory. Clearances containing targets that cannot be transferred without assumptions directly into a 4D trajectory update will have to be discontinued. Data exchange required to maintain the common data base cannot be conducted via voice. The data link used therefore becomes essential to the overall process and must be redundant. The data transferred must be unambiguous in that it shall not require any interpretation or assumptions prior its use. Airborne Separation Assistance Systems (ASAS), utilizing the other aircraft's ADS-B trajectory predictions, weather, terrain, and special-use airspace (SUA) information, will exploit enhanced cockpit displays along with some level of delegated self separation and station-keeping capabilities. It is planned that full gate-to-gate 4D Trajectory information shared among actors via System-Wide Information Management (SWIM) will facilitate surface, departure, flow, and arrival management. The highly accurate FMS trajectory predictions and Required Time of Arrival (RTA) guidance capabilities will be exploited to assign and perhaps 'sell' as a commodity, arrival slots at an arrival metering fix. The preferable metering fix will be the runway threshold itself and is highly desired from a runway-capacity standpoint. An 'on-time, first-served' concept will be applied by the airports providing equipage incentive and improved system flow. Surface Movement Guidance and Control Systems (SMGCS), again using aircraft surface trajectory (routing) data, will dramatically reduce runway incursion risks and facilitate optimized taxiing and gate usage. SMGCS will also assure that the correct flow of aircraft is established as well as tie the ground operations into the overall 4D operational concept.