In-flight Icing Study
Investigation of the meteorological conditions associated with onset of inflight icing
Herrera, J. A., D. R. Vollmer, and M. L. Gauthier
This study uses data sets retrieved from the AIRS (Alliance Icing Research Study) experiment containing measurements from the RID (Rosemount Ice Detector) and aircraft cloud microphysical measuring devices to conduct statistical analyses for ascertaining the meteorological conditions most associated with the onset of inflight icing. In situ measures of ambient air temperature, dew point, and cloud liquid water content (LWC) were correlated with voltage responses of the RID to determine when possible icing was occurring within the data. Consistent with other icing studies that used the RID, a voltage threshold for icing was inferred using the observed voltage spike which occurs once a threshold amount of ice mass has accumulated on the sensor. Comparing time-series graphs of temperature, dew point, and LWC with RID voltage, it was observed that the voltage effectively spiked when trends in the other measurements likely favored icing conditions. These favorable conditions were assumed to be when temperature was below 0°C (measurements were never less than -30°C), dew point was within 3°C of temperature, and a sufficient amount of LWC was present (>0 g m-3). Following these prescribed conditions, statistical analyses were performed to determine probability distributions for specific icing onset conditions. The data were further analyzed to determine, as a function of distance from onset, trends in temperature, dew point, and LWC associated with impending icing conditions with an eye toward developing inflight icing warning criteria.