At the EUROCONTROL-CANSO Sustainable Skies Conference experts from EUROCONTROL’s Maastricht Upper Airspace Control Centre (MUAC) shared lessons learned from the world’s first live contrail prevention trial and real-time simulations. MUAC's live contrail prevention trial and real-time simulations show that contrail formation and their harmful impact towards climate change can be avoided with relatively small vertical deviations from the flight plan. As long as air traffic is low also the impact of contrail prevention operations on capacity is low. However, capacity reductions in the range of 20% can already be expected in moderate traffic conditions for safety reasons. (....)