4619 20200127104559.0 CTALK-2020-0048 Wilken, V. PECASUS - GNSS Service Domain 2019 2019-12-11 The PECASUS (Pan-European Consortium for Aviation Space weather User Services) initiative aims for a global space weather information service center as specified by the International Civil Aviation Organization (ICAO) in its State Letter (AN 10/1-IND/17/11) released in June 2017. The countries forming the PECASUS consortium are Finland (Lead), Belgium, UK, Poland, Germany, Netherlands, Italy, Austria, and Cyprus. One of the four planned 'Expert Groups' is engaged with the development of the 'GNSS user domain service' and are formed by INGV (Istituto Nazionale di Geofisica e Vulcanologia), SRC PAS (Space Research Centre of Polish Academy of Sciences), STCE (Solar Terrestrial Centre of Excellence), KNMI (Koninklijk Nederlands Meteorologisch Instituut) and DLR (Deutsches Zentrum für Luft- und Raumfahrt/ German Aerospace Center) which is also leading the Expert Group. The operational near-real time products and services foreseen to be delivered in the navigation domain of aviation will be explained. We demonstrate, based on examples of historical space weather events, how the actual PECASUS products can be beneficial for aviation during such events. Furthermore, we discuss messaging formats and thresholds recently used to inform the aviation community. PECASUS/ PECASUS/ PECASUS STCE Kriegel, M. Berdermann, J. Cesaroni, C. Spogli, L. Romano, V. Bergeot, N. Chevalier, J.-M. Stanislawska, I. Tomasik, L. van den Oord, B. AGU Fall Meeting 2019, San Francisco, USA jean-marie.chevalier@observatoire.be Contributed CTALKCONT