Icing Wind Tunnel. Exterior of the Icing Wind Tunnel (IWT), one of the facilities at the Italian Aerospace Research Centre (CIRA). This system generates icy clouds. The IWT is the only facility able to replicate the conditions of humidity, cold and wind experienced by an aircraft at altitude. This allows the study of how ice formation on an aircraft affects its performance and also the testing of de-icing systems. The IWT conditions range from wind speeds of Mach 0.25 to 0.7, altitudes of up to 7000 metres, humidities between 70% and 100%, and temperatures from -40 to 35 degrees Celsius. CIRA, founded in 1984, is in Capua, Italy.