This report provides a comprehensive assessment of the current state of scientific knowledge regarding atmospheric icing and its implications for aviation safety, operations, and regulation, both now and under future climatic conditions. It is part of a broader initiative under the European Union Aviation Safety Agency (EASA) European Network – Impact of Climate Change on Aviation (EN-ICCA), aimed at understanding how evolving climate conditions may affect aviation-relevant weather hazards.
Atmospheric icing phenomena such as supercooled liquid droplets, ice crystals, and mixed-phase conditions, pose significant risks to aircraft performance, engine reliability, and flight safety. The report outlines the causes and forms of icing, the meteorological conditions that contribute to its occurrence, and the physical properties that influence its severity. It assesses the vulnerability of different aircraft types and flight phases to icing.
The study reviews current industry practices for managing icing hazards, including design and certification standards, operational procedures, and forecasting techniques. It identifies limitations in existing models and forecasting tools, especially in accurately predicting icing severity and in-flight ice crystal conditions. The report also explores the role of numerical weather prediction (NWP) and nowcasting technologies, noting recent advances in forecasting capability despite the need to increase model resolution, and ongoing gaps in observational data and microphysical representation capabilities.
Data on future trends in atmospheric icing remain limited. However, preliminary studies suggest shifts in the frequency, altitude, and severity of icing conditions due to climate change. The report calls for improved climatological studies, enhanced observational datasets, and refined modelling approaches to better understand and anticipate these changes.
To address the knowledge gaps identified and progress understanding of past and future trends of atmospheric icing, two strategic workstreams are recommended. Work Stream 1 will focus on developing and validating icing indices and input data for climatology studies. Work Stream 2 will focus on conducting climatological studies using reanalysis and climate model outputs. These efforts aim to support the aviation sector in adapting to evolving atmospheric hazards and maintaining high safety standards in a changing climate.