This information can then be used in a number of ways to control road usage. It could, for example, be used to charge motorists for using a stretch of road, to restrict access to congested roads, or to inform drivers of congestion and suggest alternative, quieter routes. When planning aircraft routes and landing schedules at busy airports, it is essential to ensure that aircraft are always a safe distance from each other. But if you could be confident of knowing precisely where the planes are, you could reduce the margins safely and increase capacity, he adds. Galileo, the satellite navigation system under development in Europe, will provide a guaranteed service with sufficient accuracy to allow airlines and pilots to know their position reliably and precisely enough to make substantial efficiency savings.
Satellite navigation can also help pilots to land planes safely, especially in poor weather.
At present, this is possible only with differential satellite navigation in which an antenna close to the runway transmits a signal to the navigational satellites. Small airports are unlikely to invest in this technology, but when Galileo becomes operational the need for a differential antenna will reduce. Galileo s guaranteed service and use of dual frequencies will increase accuracy and reliability to such an extent that planes will be able to use its navigational signals for guidance using their on-board technology alone.