WAAS - (Wide Area Augmentation System)
A satellite navigation system designed by the U.S. Federal Aviation Administration (FAA) to boost the accuracy of GPS satellite navigation. Improvements in accuracy are approximated to be within 7 meters. Note: Currently, WAAS is not fully implemented. It was created for aviation applications. It uses geostationary satellites over the equator, which makes WAAS signals easily blocked in North America by terrain obstructions. Users may experience temporary loss of WAAS support, especially in wooded areas.