4D-trajectory time windows: definition and uncertainty management

Abstract

Purpose The use of the 4D trajectory operational concept in the future air traffic management (ATM) system will require the aircraft to meet very accurately an arrival time over a designated checkpoint. To do this, time intervals known as time windows (TW) are defined. The purpose of this paper is to develop a methodology to characterise these TWs and to manage the uncertainty associated with the evolution of 4D trajectories. Design/methodology/approach 4D trajectories are modelled using a point mass model and EUROCONTROL’s BADA methodology. The authors stochastically evaluate the variability of the parameters that influence 4D trajectories using Monte Carlo simulation. This enables the authors to delimit TWs for several checkpoints. Finally, the authors set out a causal model, based on a Bayesian network approach, to evaluate the impact of variations in fundamental parameters at the chosen checkpoints. Findings The initial results show that the proposed TW model limits the deviation in time to less than 27 s at the checkpoints of an en-route segment (300 NM). Practical implications The objective of new trajectory-based operations is to efficiently and strategically manage the expected increase in air traffic volumes and to apply tactical interventions as a last resort only. We need new tools to support 4D trajectory management functions such as strategic and collaborative planning. The authors propose a novel approach for to ensure aircraft punctuality. Originality/value The main contribution of the paper is the development of a model to deal with uncertainty and to increase predictability in 4D trajectories, which are key elements of the future airspace operational environment.

Practical implementation of 4D-trajectories in air traffic management: system requirements and time windows monitoring

“…Results reflect the stochastic nature of the evolution of the flight by including actual uncertainties in the ideal trajectory prediction. Once the simulations have been performed, we can define the expected TW at each CP of the agreed trajectory, thereby, providing AUs, ANSPs and airspace operators with a framework for traffic synchronization and conflict resolution (Rodríguez-Sanz et al, 2019). The size of a TW on a RBT should at least represent the time interval within any aircraft arriving at the CP to avoid collisions with other aircraft (Han et al, 2010).…”

Probabilistic Strategic Conflict-Management for 4D Trajectories in Free-Route Airspace

“…Herein, N waypoints are fixed for time-windows requirements of 4DT. They are separated by a constant distance l that is being currently considered from 150 to 200 NM because the path degradation can be assumed [4]. The N waypoints are uniformly distributed from the ToC to the ToD.…”

“…This operational framework foresees trajectory restrictions regarding time: users will follow trajectories without practically any geographical limitations (according to free-route trajectories), as long as they comply with the planned times. Thus, the main objective of this approach is to ensure an optimal trajectory (free-route trajectory whenever would be possible) by "forcing" the aircraft to accurately meet the time of arrival at designated waypoints in exchange [4]. Most of the proposed methods to 2 of 17 model 4DT and solve the aircraft trajectory prediction problem can be categorised into two approaches: deterministic and probabilistic [5].…”

Air traffic management based on 4D-trajectories: requirements and practical implementation

“…The results reflect the stochastic nature of the evolution of the flight by including actual uncertainties in trajectory prediction. Once the simulations have been performed, we can define the expected TW at each checkpoint of the agreed trajectory, thereby, providing airspace users, ANSPs and airspace operators with a framework for traffic synchronization and conflict resolution [17]. The size of a TW on a Reference Business Trajectory (RBT) should at least represent the time interval within which any aircraft arriving at the checkpoint can avoid collisions with other aircraft [19].…”

“…We propose to manage uncertainty with respect to time by establishing several intermediate locations (checkpoints) along a trajectory, where time uncertainty can be constrained by TWs. The methodology for defining TWs uses an aircraft performance model based on EUROCONTROL's Base of Aircraft Data (BADA) family 4.0 [15] and probabilistic approaches to reflect the inherently stochastic nature of air traffic procedures [16], [17].…”