New Approach

摘要

Though the Global Positioning System—24 satellites and their associated ground stations—was once the sole province of the U.S. Department of Defense, by now it is being used by everyone from offshore oil drillers to a guy in his car looking for the nearest pizza parlor. Yet as widespread as its uses have become, one benefit sought from GPS has yet to be realized: positioning precise enough to land aircraft in low visibility. This September, the Federal Aviation Administration will make available a GPS-based network built to offer pilots that degree of precision.