Individualism in global airspace-user-preferred trajectories in future ATM

Both future air traffic management programs SESAR and NextGen foresee trajectory based operations as one of the major enablers for more efficient handling of air traffic. Furthermore, both initiatives claim to support user preferred trajectories. However, using a common airspace it is unlikely to get a conflict-free scenario from independently optimized trajectories. This paper investigates if the concept of user-preferred trajectories is feasible, and what constraints are necessary to reach a conflict-free global scenario based on independently optimized trajectories. Based on a traffic scenario with ~33k individually optimized trajectories yielding ~29k conflicts, a strategic resolution is performed generating least possible penalties for involved aircraft. The main technique for solving conflicts is shifting whole flights in time by a few minutes. Direct and recursive algorithms are presented; a focus is put on solving airport-related conflicts first. More than 94% of all conflicts can be solved by shifting whole flights in time respecting a maximum offset of 10 minutes.