Volcanic emission is a threat to ATM and the safety of flights. Early warnings are an essential source of information for the stakeholders. The OPAS project is the development of a SWIM Technical Infrastructure Yellow Profile service providing information (notification & data access) about volcanic SO2 height. The OPAS service considers observations from three hyperspectral satellite sensors (TROPOMI, IASI-A and IASI-B), respectively operating in the ultraviolet and infrared ranges. These instruments represent the state of the art of satellite SO2 measurements. The IASI sensor already provides well recognised estimations of SO2 height, which is available through the SACS early warning system and contributes to the OPAS service. The outcome of the OPAS project is the new algorithmic development (iterative SO2 optical depth fitting) of TROPOMI SO2 height retrievals, the creation of alerts and the access to tailored information, i.e. SO2 contamination of flight level and improved mass loading estimates.