Impacts of ATC Related Maneuvers on Meeting a Required Time of Arrival

The next generation air transportation system (NGATS) as defined by the Joint Planning and Development Office includes trajectory-based operations (TBO) as part of its concept of operation. TBO are envisioned to form the basis for both more strategic planning in the NGATS and for more tactical operations including separation management. The cornerstone of this concept is the establishment of a four-dimensional trajectory. The concept also calls for the use of a controlled time of arrival (CTA) to help manage the use of a specific system resource. A flight management system (FMS) onboard the aircraft has capabilities that may prove useful when operating under TBO. Such capabilities include required time of arrival (RTA) - the capability to "self-deliver" to a specified waypoint at a specified time. The RTA capability may be employed to implement a CTA. This paper presents an investigation into the FMS capabilities to meet an RTA and looks at the impact of using a lateral offset maneuver to address a tactical situation has on a flight's ability to meet an RTA. Several PC-based models of a Smiths Aerospace FMS/Boeing 737 aircraft were used during this investigation. This study focused on an RTA at a waypoint during the cruise phase of a flight