Clearing Up Aviation Ice Forecasting

NCAR has developed a new forecasting system for aircraft icing that delivers 12-hour forecasts updated hourly for air space over the continental United States. The Forecast Icing Product with Severity, or FIP-Severity, measures cloud-top temperatures, atmospheric humidity in vertical columns, and other conditions and then utilizes a fuzzy logic algorithm to identify cloud types and the potential for precipitation in the air, ultimately providing a forecast of both the probability and the severity of icing. The system is an update of a previous NCAR forecast product that only was capable of estimating uncalibrated icing “potential.”
The new icing forecasts should be especially valuable for commuter planes and smaller aircraft, which are more susceptible to icing accidents because they fly at lower altitudes than commercial jets and are often not equipped with de-icing instruments. The new FIP-Severity icing forecasts are available on the NWS Aviation Weather Center’s Aviation Digital Data Service website.
According to NCAR, aviation icing incidents cost the industry approximately $20 million per year, and in recent Congressional testimony, the chairman of the National Transportation Safety Board (NTSB) noted that between 1998 and 2007 there were more than 200 deaths resulting from accidents involving ice on airplanes.

This graphic from the FIP-Severity software program shows a 2-hour icing severity forecast for the United States on March 15, 2011. The forecast is for a column extending from 1,000 to 30,000 feet above mean sea level. The shades of blue denote the level of severity, and the red areas of "SLD threat" are warnings for the presence of "supercooled large drops," which include freezing drizzle/freezing rain and indicate severe icing potential. (Image courtesy NOAA/NWS/ADDS.)