A major technological shift in air navigation became a reality today. The FAA flicked the switch on the Wide Area Augmentation System (WAAS) signal, a crucial first step on the way to highly accurate satellite-based navigation in the U.S. "We're just waiting for the avionics to catch up," said FAA spokesman Greg Martin. WAAS uses a system of ground stations to analyze GPS signal errors and sends corrections to geo-stationary satellites. The result is guaranteed position accuracy to within three meters laterally and vertically, where standard non-augmented GPS with standard positioning service can be trusted to within about 100 meters. Martin said WAAS-capable GPS units will pick up the signal starting today but it will be at least a month before the full utility of the system comes into play. That's still good news -- the last deadline for WAAS's initial operational capability schedule was the end of 2003. Martin said there are currently no GPS units certified for the vertical part of the WAAS signal, which is essential for instrument landings. However, Martin said there are several manufacturers aggressively pursuing the vertical certification, and GPS ILS approaches could be reality sometime in August or September. As an example, the UPSAT CNX-80 is expected to achieve certification shortly.