An aviation support tool for satellite remote detection of in-flight icing.

In-flight icing, i.e. the accretion of ice on airplane’s surfaces during flight, is caused by supercooled water droplets that freeze instantly when they impact the airframe and it represents a critical meteorological risk to aviation as it affects aircraft performance, stability and controllability. Therefore, the remote detection of weather conditions leading to in-flight icing is a goal of great interest to the scientific community. In 2017, the Meteorological Laboratory of CIRA has developed a first satellite-based tool for in-flight icing detection in collaboration with Italian Air Force Meteorological Service. This tool is based on several high-resolution satellite products of Meteosat Second Generation (MSG) and a set of experimental curves and envelopes describing the interrelationship of icing-related cloud variables that represent the icing reference certification rules, namely Appendix C to FAA 14 CFR Part 25 / EASA CS-25. However, Appendix C data do not consider Supercooled Large Droplets (SLD), which have been the cause of tragic accidents over the last decades and that have been introduced in new certification procedures and guidelines through the Appendix O, effective as of 2015. In the framework of the H2020 EU project SENS4ICE (SENSors and certifiable hybrid architectures for safer aviation in ICing Environment) started in 2019, CIRA is working on a further maturation of the previously developed icing detection algorithm, in order to consider also Appendix O Icing Conditions. The developed tool is targeted to identify areas potentially affected by in flight icing hazard, giving an estimate of the altitude and of the severity of the phenomenon (light, moderate, severe) with indication of possible SLD conditions. In the present work an overall description of the implemented tool is provided along with an analysis of its performance. Due to the lack of suitable in-situ observations of icing conditions, a complete validation of the developed product is challenging. A comparison with significant weather charts has been performed and other validation activities based on the comparison with soundings data are ongoing, showing quite good results. Furthermore, this tool is currently being used in the framework of the SENS4ICE flight test campaign (scheduled in April 2023), which represents a good opportunity to evaluate its performance in environmental icing conditions. During the flight tests, information on monitoring of icing conditions are provided in the pre-flight phase and updated in near-real time. The outcomes of the flight test campaign will be exploited to identify the strengths and weaknesses of the algorithm. Acknowledgment: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement N° 824253 (SENS4ICE project).