Flight guidance of aircrafts in continuous descent operation based on 4D trajectory

Continuous descent operation (CDO) is an operating technique to reduce fuel consumption, noise and emissions during descent. Because the uncertainty of trajectory increases with CDO and the traffic density in terminal area decreases, CDO is only applied in the low-density airports or time interval. In order to implement CDO in high traffic density environment, the technique of 4D trajectorybased operation is necessary to reduce the uncertainty of trajectory, and a precise 4D flight guidance oriented to time of arrival can be implemented by 4D trajectory prediction and 4D flight guidance system. In this paper, a scheme of 4D flight guidance system based on 4D trajectory for airliners is proposed, and the describing method about 4D trajectory is given, and the planning procedure of 4D trajectory with multi-constraints is depicted. To improve the predicting precision of ETA (estimated time of arrival), a ground speed calculation method based on pseudo waypoint is proposed, and a speed adjusting strategy according to RTA (required time of arrival) and longitudinal position error is provided in the end. To demonstrate the validation of the algorithms given in the paper, the simulation based on a type of domestically-made carrier is operated, and it is can be drawn from the simulation result that the guidance algorithms and the strategy given in the paper could provide a precise 4D flight guidance oriented to time of arrival for airliners.