National Airspace System Persistent Problems in FAA's New Navigation System Highlight Need for Periodic Reevaluation

Currently, the Federal Aviation Administration FAA relies principally on a ground-bases navigation system that uses various types of equipment to assist pilots in navigating their assigned route and to provide them with guidance for landing their aircraft safely in different types of weather. However, this ground-based navigation system is aging and limited in its geographic coverage. FAA is planning a transition from its ground-based navigating system to a satellite-based system using radio signals generated by Global Positioning System GPS to provide greater geographic coverage, among other things. The Department of Defense developed GPS to support military missions and functions. However, the system is now a dual-use system, and other users --- pilots, truckers, and boaters -- rely on signals from the GPS satellites to calculate their time, speed, and position anywhere on or above the earths surface. As part of its efforts to maintain GPS and make it more useful for civilians, in May 2000, Defense ceased its practice of intentionally degrading the accuracy of the GPS signal available for civil use. Furthermore, Defense plans to begin gradually replacing the existing satellites with new ones that will also improve system performance.