ECATS International Association was invited to present state-of-the-art research and achievements during Aerodays 2011, 30 March – 1 April, in Madrid. Thematic expertise and recent scientific results from ECATS International Association were presented by Sigrun Matthes (Association Chair) in a session on Climate aspects on a Sustainable Air Transport System. Andreas Petzold presented science interface to be set up in CSA WEZARD (FP7, Weather hazards for Aeronautics) in a session on Disruptive Events for Air Transport. Sigrun Matthes presented results from CP REACT4C (FP7, Reducing Emissions from Aviation by Changing Trajectories for the benefit of climate) during a session on Air Traffic Operations. Mitigation options and assessment of total aviation climate impact were presented.