The 8th Conference on Aviation, Range, and Aerospace Meteorology

12.10
WEATHER SUPPORT TO DEICING DECISION MAKING (WSDDM)- A WINTER WEATHER NOWCASTING SYSTEM

Roy Rasmussen, NCAR, Boulder, CO; and et al

A winter weather nowcasting system has been developed under FAA funding to support winter operations at airports, including deicing operations. This system provides a 30 minute nowcast of precipitation intensity and movement, current precipitation type, temperature, and wind conditions and a current and 30 minute nowcast of liquid equivalent snowfall rate . The liquid equivalent rate has been shown to be the primary factor to cause deicing fluids to fail, and is therefore a critical piece of information for deicing operations and pilots. Research conducted has part of this program has shown that the liquid equivalent rate for five major takeoff crashes attributed to inadequate de-icing/anti-icing five accidents was between 0.08 and 0.1 inches/hour. Analyses also indicated that the visibility at the time of the accidents was suggestive of only light to moderate snow, indicating that the current NWS snowfall rate categories, which are based on visibility alone, are not adequate to use as guidance for effective ground de-icing operations. Since an accumulation of only 0.8mm of ice on a wing surface can increase drag and reduce airplane lift by 25%, accurate estimates of liquid equivalent snowfall rates are critical to safe and efficient aircraft operations during snow conditions. The WSDDM system attempts to fill this need by providing a current and a 30 minute nowcast of liquid equivalent snowfall rate at an airport by using accurate weighing snowgauges that are used in real-time to convert a 30 minute nowcast of reflectivity into a liquid equivalent snowfall rate. In this paper we describe the WSDDM system, as well as demonstrations of the system at Denver, Chicago, and New York.

We will also discuss some of the user feedback obtained during the demonstrations by the Hughes FAA Technical Center and a benefits study conducted by the Volpe Transportation Center.

The 8th Conference on Aviation, Range, and Aerospace Meteorology