aircraft conflict detection and resolution
Air Traffic Management plays a crucial role in ensuring that thousands of aircraft can safely share the same airspace every day, while maintaining efficient and reliable air transport operations. As air traffic continues to grow, air traffic controllers and automated support systems must constantly coordinate aircraft movements to prevent unsafe situations, manage congestion, and minimize delays. Within this context, one of the most critical tasks is the early identification and mitigation of potential conflicts between aircraft. This challenge is commonly referred to as the Aircraft Conflict Detection and Resolution (CD&R) problem, which focuses on detecting possible losses of separation (conflict situations) and determining appropriate actions to restore safe distances while preserving the overall efficiency of the air traffic system.
To resolve air traffic conflicts, controllers and decision-support systems can rely on a limited set of fundamental maneuvers available to aircraft. These maneuvers include changes in speed, heading (turn maneuvers), and flight level (altitude changes). Each type of maneuver has different operational implications and constraints, and effective conflict resolution strategies often require an appropriate combination of them.
One of the first works we addressed in this field was (Alonso-Ayuso et al., 2011), where speed control and altitude change maneuvers were jointly considered to resolve potential conflicts through a mixed-integer linear optimisation model. Subsequently, in (Alonso-Ayuso et al., 2012) and (Alonso-Ayuso et al., 2013), we extended this approach to a temporal framework, discretizing aircraft trajectories over a finite time horizon defined through waypoints, allowing conflicts to be detected and resolved dynamically. These contributions, together with the study of a Variable Neighborhood Search (VNS) metaheuristic to efficiently solve the temporal version of the problem, were consolidated in my Ph.D. thesis, defended in 2010 and later published in (Martín-Campo, 2012).
In (Alonso-Ayuso et al., 2013), the focus shifted to the coordination of multiple air traffic controllers managing adjacent sectors surrounding the sector under study. The model enabled controllers to issue alerts for potential conflicts, distinguishing between those likely to occur within their own sector and those in neighboring sectors, highlighting the importance of sector-to-sector coordination for maintaining overall airspace safety and efficiency.
Turn maneuvers involve inherently nonlinear conditions, which is why they have generally not been addressed in the literature using linear programming models. Nevertheless, in (Alonso-Ayuso et al., 2012) and (Alonso-Ayuso et al., 2014), we presented a VNS-based metaheuristic to solve the CD&R problem through turn maneuvers, effectively handling nonlinearities and providing feasible solutions within reasonable computational times. Later, in (Alonso-Ayuso et al., 2016), we proposed a mixed-integer nonlinear optimisation model along with an iterative solution procedure, further improving the capability to resolve conflicts involving turn maneuvers while maintaining computational efficiency.
When integrating all three maneuvers simultaneously, it becomes necessary to balance their use according to comfort and economic considerations. To address this, (Alonso-Ayuso et al., 2015) presented a multicriteria exact procedure for combining the three maneuvers. Subsequently, (Alonso-Ayuso et al., 2016) introduced an iterative procedure capable of producing solutions in very short computational times. Finally, (Alonso-Ayuso et al., 2017) proposed a VNS-based procedure to efficiently solve the multicriteria problem, achieving a balance between effectiveness and computational efficiency.
