The Wide Area Augmentation System, or WAAS for short, consists of both satellites and ground based stations that supply correction information for your GPS receiver. This correction information can provide an improvement in positional accuracy of up to five times greater. It corrects for GPS signal errors caused by atmospheric disturbances, timing, and other errors. WAAS was developed by the FAA in order to help increase the accuracy of precision flight approaches. The corrected information is broadcast through two geostationary satellites that are located at a fixed location over the equator.