The long-term operational concept of this research is to develop an onboard aircraft system that assesses and reports atmospheric icing conditions automatically and in a timely manner in order to improve aviation safety and the efficiency of aircraft operations via improved real-time and forecast weather products. The idea is to use current measurement capabilities on aircraft equipped with icing sensors and in-flight data communication technologies as a reporting source. Without requiring expensive avionics upgrades, aircraft data must be processed and available for downlink. Ideally, the data from multiple aircraft can then be integrated (along with other real-time and modeled data) on the ground such that aviation-centered icing hazard metrics for volumes of airspace can be assessed. As the effect of icing on different aircraft types can vary, the information should be displayed in meaningful ways such that multiple types of users can understand the information. That is, information must be presented in a manner to allow users to understand the icing conditions with respect to individual concerns and aircraft capabilities. This research provides progress toward this operational concept by: identifying an aircraft platform capable of digitally capturing, processing, and downlinking icing data; identifying the required in situ icing data processing; investigating the requirements for routing the icing data for use by weather products; developing an icing case study in order to gain insight into major air carrier needs; developing and prototyping icing display concepts based on the National Center for Atmospheric Research's existing diagnostic and forecast experimental icing products; and conducting a usability study for the prototyped icing display concepts. Bass, Ellen J. and Minsk, Brian and Lindholm, Tenny and Politovich, Marcia and Reehorst, Andrew (Technical Monitor) Glenn Research Center NASA/CR-2002-211800, E-13495, NAS 1.26:211800 NASA Order C-74790-N; RTOP 708-20-13 37469 AIRCRAFT ICING; AIRCRAFT SAFETY; DATA PROCESSING; DATA SYSTEMS; FLIGHT SAFETY; AIRCRAFT HAZARDS; IN SITU MEASUREMENT; METEOROLOGICAL PARAMETERS; FLIGHT CONDITIONS; AIRSPACE; AVIONICS; DATA TRANSMISSION; DISPLAY DEVICES; DOWNLINKING; METEOROLOGICAL SERVICES; REAL TIME OPERATION; AVIATION METEOROLOGY