Study of the required time of arrival function of current FMS in an ATM context

4D-trajectory-based operations (where "D" stands for dimensional) are proposed by SESAR and NGATS as the fundamental cornerstones of air traffic management (ATM) system improvements of the future. Various research initiatives such as PHARE (M. Van Gool and H. Schroter, 1999) have long described and prototyped these ideas of integrated air-ground ATM. However, because the broad implementation of this concept requires significant harmonized development of both air-and ground-based technology, progress has been limited. Nonetheless, the avionics industry has implemented initial capabilities to manage the fourth dimension, i.e. time, called required time of arrival (RTA). The paper summarizes the results obtained from a EUROCONTROL study on the availability, characteristics and performance of the required time of arrival (RTA) function in existing flight management systems (FMS). The RTA study is first discussed in the context of ATM, proposing some guiding premises as to how the time management function should be developed. As a consequence, the RTA study focused on performance during descent, using different FMS modes. A brief discussion of related EUROCONTROL projects has also been added. Test results from a number of sessions on Boeing 737 and Airbus A320 flight simulators are then presented. The evaluation included an assessment of the impact of wind on RTA, as well as some observations about the human machine interface aspects. Lastly, conclusions and recommendations for further development are proposed.