Weather is a major cause of aircraft accidents and incidents and the single largest contributor to air traffic system delays. In fact, a recent estimate by the Federal Aviation Administration (FAA) identified weather as being responsible for nearly 70 percent of flight delays. As the amount of air traffic over the U.S. continues to increase, the tendency will be for delays to increase as well. Considering the nation's heavy reliance on commercial air transportation, any efforts to increase the safety and efficiency of air travel will result in numerous direct and indirect benefits.

The FAA's Aviation Weather Research Program (AWRP), through improvements in the knowledge of current weather conditions and reliable forecasts, has been striving to improve aviation safety, increase system capacity, and enhance flight planning and fuel efficiency. The AWRP provides the capability to generate more accurate and accessible observations, warnings, and forecasts of weather that spawns aviation hazards that can severely impact the nation's transportation system. The weather research areas that impact transportation that will be discussed in this paper include convective weather, in-flight icing, ground deicing, turbulence, ceiling and visibility, oceanic weather, and a weather information dissemination system called the Aviation Digital Data Service (ADDS).