1) The document discusses using trajectory pricing to redistribute air traffic in the European airspace by modulating en-route charges. It aims to address capacity-demand imbalances and reduce delays and costs. 2) A bilevel optimization model is formulated to find the optimal charge rates set by the central planner to minimize inefficiency in the network, while airspace users determine optimal routes and departure times based on the charges. 3) The model is implemented on real air traffic data from 17 clusters of flights in Europe. Different scenarios are tested by relaxing constraints to trade off computation time and solution quality. Modulating charges resulted in redistributing over 14,000 minutes of flight time across scenarios.