This paper considers the problems of improving the safety and efficiency of air traffic flows. Particular attention is paid to promising methods for detecting and resolving aircraft conflicts. These methods are classified. We study the problem of minimizing the number of potential conflicts with a promising air traffic control technology, the strategic deconfliction of 4D trajectories. We present a mathematical model to consider uncertainty in the strategic deconfliction of 4D trajectories, a corresponding formal statement as a mixed integer programming problem, and some approaches to solve this problem. Estimating the objective function requires calculating the number of potential conflicts between aircraft. Under uncertainty, this estimation involves a large amount of computations. We discuss an alternative approach to airspace capacity estimation based on air traffic complexity depending on the traffic structure and geometry of the airspace.