Modernization does not stop here. ADS-B doesn't need to interrogate targets to display them. Rather, it relies on the satellite-based Global Positioning System. Each ADS-B equipped aircraft broadcasts its precise position in space via a digital data link. ADS-B is an exciting development, but it is just one piece of the future.
Modernization includes the transition to satellite navigation.
A number of special-use LAAS units are in use and have demonstrated the technical feasibility and value of this technology. Yet, in a country the size of the U.S., we simply cannot afford to install and maintain a comprehensive network of LAAS's. That's why we are developing wide area capability, through WAAS, to provide similar service at airports across the country, while also providing en route navigation. The challenge remaining for us is to make the necessary logic and engineering changes to meet rigorous safety certification standards we have set for integrity monitoring. We are expecting the results of an independent review of the WAAS program and we are encouraged by the preliminary findings that we believe will validate that we are on the right path.