Document Type


Publication Date





Four-dimensional trajectory-based operations (4D TBO) requiring aircraft to meet specified timing constraints at designated waypoints along their route are a key strategy for increasing airspace throughput and efficiency. The Required Time of Arrival (RTA) function of the aircraft Flight Management System (FMS) and the ground-based Traffic Management Advisor (TMA) were tested for supporting such operations. Two different methods for implementing appropriate time intervals between sequential RTA aircraft were explored in this paper: a fixed 90-second interval versus discrete intervals varied to match the prevailing conditions. Both methods yielded a good balance between separation assurance and flow efficiency. Three different types of FMS were included in this study; the results validated the performance of the FMSs to achieve the assigned RTA clearance time, although there were some issues with meeting the altitude and airspeed restrictions specified at the meter fix, likely due to the need to actively manage speed on descent given current FMS functionality. Human factors issues in need of further examination are presented.