"It is proposed to establish a sustainable distributed infrastructure for global observations of atmospheric composition from a large fleet of in-service aircraft. This will be achieved by installing autonomous instrument packages aboard initially 10-20 longrange aircraft of internationally operating airlines. IAGOS-ERI will provide high quality in-situ observations of greenhouse gases and reactive gases, aerosol, and cloud particles in the tropopause region, which is not adequately resolved by remote sensing from space and, on the other hand is one of the most sensitive regions for climate change. At the same time, IAGOS-ERI will provide detailed vertical profiles in the troposphere, which are of paramount importance for predicting changes in local and regional air quality and its causes. The main goals of the preparatory phase are to prepare the legal and organisational structure and funding scheme for the new RI, to obtain the necessary legal preconditions for sustainable deployment of scientific instrumentation and near-realtime data transmission on in-service aircraft, insofar not yet achieved during the design study (IAGOS-DS), the coordination with the scientific and operational user community, such as WMO, AMDAR, ECMWF, and the implementation of IAGOS-ERI into the global observing system established by WMO-GAW within GEOSS. Technical work is required for bringing CARIBIC into routine operation, the deployment of very small instrument packages on a wider fleet of aircraft, and for cooperation with WMO-AMDAR for routine water vapour measurements."