EGNOS, the European Geostationary Navigation Overlay Service, a project jointly co-ordinated by the European Space Agency (ESA) and Eurocontrol, the European Organisation for the Safety of Air Navigation, is a regional complement to the existing military-controlled US GPS and Russian GLONASS satellite navigation systems. Consisting of three geostationary satellites – the two Inmarsat-3 satellites, carrying the first European navigation payload, and ESA’s Artemis (Advanced Relay and Technology MISsion) communications satellite – and a network of ground stations, it will transmit a signal providing information on the accuracy of positioning signals sent out by GPS and GLONASS. With EGNOS, users over a geographical area covering Europe, the Atlantic and Indian Oceans, South America, Africa, the Middle East and Central Asia will be able to determine their position to within 5 metres as opposed to the (approximately) 20 metre-precision afforded by GPS or GLONASS alone, ensuring much greater reliability and service integrity for safety-critical civil applications, such as aircraft.
Expected to be operational in 2005, EGNOS is the first stage of the European Union’s policy on a Global Navigation Satellite System (GNSS-1). From 2006–2008, the EGNOS infrastructure will be integrated into the second phase, GNSS-2, the new satellite navigation system Galileo, which will be interoperable with GPS or GLONASS but capable of functioning independently.
