Aviation-based winter weather research at RAL, sponsored by the Federal Aviation Administration, has focused on developing two new systems in support of Ground Deicing operations. The Liquid Water Equivalent (LWE) system combines a Hotplate and GEONOR snow gauge; a Vaisala PWD–22 precipitation type sensor; a Campbell freezing rain sensor; a Vaisala WXT wind, temperature, and humidity sensor; and a Decagon Leaf Wetness Sensor to estimate a real–time liquid water equivalent precipitation rate. This rate is a critical component of the Checktime® System, a UCAR patented technology for aircraft ground deicing operations, that determines when deicing/anti-icing fluids applied to aircraft are close to failure based on temperature measurements and precipitation rates that are updated every minute from the LWE system. Checktime® is aircraft independent and only requires the end user to know the time that the aircraft was deiced. Demonstrations of the LWE and Checktime® systems are conducted at Denver International Airpot, Chicago's O'Hare International Airport, and the Clevel-Hopkins International Airport. LWE's ability to detect ice pellets has been tested at St. John's, Newfoundland, Canada, the site of the climatological maximum of freezing precipitation and ice pellets in North America.