The European Geostationary Navigation Overlay Service (EGNOS)



What is the European Geostationary Navigation Overlay Service (EGNOS)?

EGNOS is Europe’s Satellite-based Augmentation System (SBAS). A Satellite-Based Augmentation System (SBAS) is a system that enhances the performance, accuracy, and reliability of standard satellite navigation signals, such as those provided by GPS (Global Positioning System), or Galileo (the European Union's satellite navigation system). SBAS is primarily used to support safety-critical applications, especially in the aviation sector, but also benefits other modes of transport and activities requiring precise location data.

SBAS systems are implemented regionally around the world to serve different areas. Notable examples include:

- WAAS (Wide Area Augmentation System) in North America.

- EGNOS (European Geostationary Navigation Overlay Service) in Europe.

- MSAS (MTSAT Satellite Augmentation System) in Japan.

- GAGAN (GPS Aided Geo Augmented Navigation) in India.

A new, more powerful system called ‘EGNOS V3’ is currently under preparation. It will strengthen both Galileo and GPS signals, resulting in an even better user experience.

As a regional navigation satellite system, EGNOS’ coverage is limited to Europe and some neighborhood countries.


How EGNOS works

Ground stations deployed around Europe acquire signals from GPS (and, tomorrow, from Galileo), which are then gathered and processed through a central computing system. Here, differential corrections and integrity messages are calculated. These messages are then broadcast back to users across Europe via a set of three geostationary satellites.

As a result, EGNOS improves the accuracy of GNSS positioning information while also providing a crucial integrity message which allows the user to get an extremely reliable guarantee on its residual positioning errors (both horizontal and vertical). In addition, EGNOS signals provide the users with a very accurate synchronization to the UTC time.

Benefits

EGNOS is essential for applications where accuracy and integrity are critical, such as aviation. In fact, since its certification for use in civil aviation in 2011, EGNOS has become an important aid in the European aviation sector, increasing both the safety and accessibility of airports in general and, in particular, small and regional airports and airfields. Thanks to the accurate and safe guidance offered by the system everywhere and anytime in Europe, pilots are better positioned to land in challenging weather conditions, including poor visibility and storms, and avoid aborted landings (go-arounds).

Maritime users are also widely using EGNOS for harbor entrances, harbor approaches and coastal waters in the EU.

Beyond these sectors, EGNOS improves and extends the scope of GNSS applications in numerous market segments, including road, rail, surveying, mapping, location-based services and agriculture – to name only a few.


Infrastructure

The EGNOS infrastructure is comprised of:

- A ground network of about 40 ranging and integrity monitoring stations (RIMS)

- 6 navigation land earth stations (NLES)

- 2 mission control centres

- An Operations Coordination Center and a Service Centre

- Signal transponders on 3 geostationary satellites operated by SATCOM service providers

The Directorate-General for Defence Industry and Space (DG-DEFIS), that leads the European Commission's activities in the Defence Industry and Space sector, is in charge of implementing the EU Space programme consisting of the European Earth Observation Programme (Copernicus), the European Global Navigation Satellite System (Galileo) and the European Geostationary Navigation Overlay Service (EGNOS).