The Aircraft Icing Environment in Wintertime, Low Ceiling Conditions.

Abstract : Radiosonde (Raob) temperature and humidity data were used to deduce the vertical distribution of clouds and aircraft icing conditions near Washington, DC when low ceilings (- or 1000 ft)(0/3 km) occurred along with surface temperatures near freezing. Automated predictions of the vertical distribution of icing probability, type, and severity were generated from the Raob data. The technique employs a U.S. Air Force method that has been computerized by one of the authors (RKJ) for use on Hewlett Packard model 9845 computers. The predictions were compared with pilot reports from the vicinity and reasonable agreement was found. Results: Vertical Distribution of Clouds Above Cold, Low Ceilings; Effects of Local Topography on Height of Cold, Low Ceilings; Vertical Profiles of Icing Conditions; Computation of Icing Conditions from Raob Data; Comparison of Forecasted Icing Conditions with Pilot Reports.