European Geostationary Navigation Overlay Service
European satellite-based augmentation system for GPS and future Galileo.
The European Geostationary Navigation Overlay Service (EGNOS) is a satellite-based augmentation system (SBAS) built by the European Space Agency and Eurocontrol for the European Commission. It currently improves GPS by checking the reliability and accuracy of positioning data and broadcasting corrections. A future version, EGNOS V3, will also support Galileo. The system’s infrastructure includes 40 Ranging Integrity Monitoring Stations, two Mission Control Centres, six Navigation Land Earth Stations, the EGNOS Wide Area Network (EWAN), and three geostationary satellites. Ground stations assess how accurate satellite navigation data is and send that information to the geostationary satellites; anyone with an EGNOS-enabled receiver can get this data for free from those satellites, or via the Internet. Aviation is a primary use case. According to specifications, horizontal accuracy with EGNOS corrections should be better than seven metres, but in practice it reaches the metre level. Similar services exist elsewhere: North America’s WAAS, Russia’s SDCM, Japan’s MSAS, and India’s GAGAN. For the 2021–2027 period, Galileo and EGNOS together received a budget of €14.6 billion for research and development.
EGNOS began initial operations in July 2005, offering accuracy better than two metres and availability above 99%. It has broadcast a continuous signal ever since. One early use was tracking cyclists in the Tour de France. In 2009, the European Commission signed a contract with the European Satellite Services Provider to run EGNOS, and officially announced the start of operations on 1 October 2009. The system was certified for safety-of-life applications in March 2011. An EGNOS Data Access Service became available in July 2012. By the mid-2010s, initial work to extend coverage to Southern Africa was underway through a project called ESESA. The European Commission is defining a roadmap for EGNOS’s evolution, covering legacy and new missions: from 2011 to 2030, it will provide en-route, NPA, APV1, and LPV200 services based on GPS L1 augmentation, with Safety of Life guaranteed until 2030 per ICAO SBAS standards. From 2020 onward, EGNOS V3 is planned, including the SBAS L1/L5 standard, dual-frequency capability, and a multi-constellation approach.
Quick Facts
- Operator
- EUSPA, ESA
- Coverage
- Europe, North Africa
- Cost
- €1,1 billion
- Country
- European Union
Facts from the source article.
Lore & Background
EGNOS started initial operations in July 2005, with accuracy better than two metres and availability above 99%, and has broadcast a continuous signal since then. One of its first uses was tracking cyclists in the Tour de France. In 2009, the European Commission signed a contract with the European Satellite Services Provider to run EGNOS, and official operations began on 1 October 2009. The system was certified for safety of life applications in March 2011, and an EGNOS Data Access Service became available in July 2012. By the mid 2010s, initial work to extend coverage to Southern Africa was underway via the ESESA project. In 2021, following Brexit, the United Kingdom withdrew regulatory approval for EGNOS, and aircraft pilots were no longer permitted to use the system. Similar services include North America's WAAS, Russia's SDCM, Japan's MSAS, and India's GAGAN.
Reader's Guide
EGNOS is significant as Europe's primary satellite-based augmentation system, providing correction and integrity data that improves GPS accuracy from several metres to the metre level. Its Safety of Life service, certified in March 2011, supports civil aviation operations down to Localizer Performance with Vertical Guidance minima, allowing pilots to land in instrument meteorological conditions using GPS approaches. The system's open service is available free of charge to any user with an appropriate receiver, while the EGNOS Data Access Service offers ground-based access for commercial and professional users. The roadmap includes evolution to EGNOS V3, which will implement the SBAS L1/L5 standard, dual-frequency operation, and multi-constellation capability. Despite limitations in urban areas due to low geostationary satellite elevation, the SISNeT internet service was developed to deliver EGNOS signals to ground users. The system's architecture, with redundant ground and space segments, ensures high availability and integrity for applications in aviation, agriculture, maritime, rail, mapping, and location-based services.
Ground-to-Orbit: The EGNOS Infrastructure
EGNOS operates through a carefully layered ground-and-space architecture. At the foundation sits a network of forty Ranging Integrity Monitoring Stations spread across Europe and North Africa. Each RIMS continuously collects raw measurements from GPS satellites and relays that data every second to the Central Processing Facilities housed within two Mission Control Centres. Those centres are the analytical brain of the system: they compute the correction messages that compensate for satellite clock drift, orbital position errors, and ionospheric delays, and they simultaneously generate integrity messages that flag any satellite whose signal has become unreliable. The correction and integrity data are then uplinked through two Navigation Land Earth Stations assigned to each of the three geostationary satellites. The EGNOS Wide Area Network stitches all of these ground components together into a single communication backbone. End users receive the broadcast corrections either directly from the geostationary satellites with an EGNOS-capable receiver or over the Internet, making the service accessible without dedicated hardware.
Three Tiers of Service for Different Users
EGNOS delivers its value through three distinct service layers, each tailored to a different class of user. The Open Service, live since 1 October 2009, is the broadest and most accessible tier. It corrects ranging errors caused by satellite clock offsets, orbital inaccuracies, and ionospheric propagation delays, and it can also detect signal distortions so that receivers avoid tracking unhealthy or misleading satellites. Crucially, it is free of charge across Europe and requires no special receiver certification—any GPS/SBAS-compatible device can benefit. The Safety of Life service, certified in March 2011, targets the most demanding applications, primarily civil aviation operations down to Localizer Performance with Vertical Guidance minima. Its signal-in-space performance is designed to meet ICAO SBAS Standards and Recommended Practices, and while aviation is the primary focus, the service is also envisioned for maritime, rail, and road applications. The third layer, the EGNOS Data Access Service, launched in July 2012, provides ground-based, real-time and historical FTP archive access to the data generated by the entire European and North African ground infrastructure, aimed at commercial and professional users who need enhanced performance.
From Tour de France to Brexit: A Timeline of Milestones
EGNOS first began broadcasting in July 2005, already delivering accuracy better than two metres with availability above 99 percent. One of its earliest public demonstrations was tracking the peloton of cyclists during the Tour de France. The European Commission formally launched operations on 1 October 2009 after signing a management contract with the European Satellite Services Provider. Two years later, in March 2011, the system earned certification for Safety of Life applications, a critical step for aviation. The Data Access Service followed in July 2012. By the mid-2010s, planners were already looking beyond Europe: the ESESA project began extending EGNOS coverage into Southern Africa. The European Commission has since defined a long-range roadmap. Through 2030, the system will guarantee Safety of Life performance using GPS L1 augmentation in line with ICAO standards. From 2020 onward, a major evolution called EGNOS V3 is planned, introducing dual-frequency L1/L5 operation and a multi-constellation concept that will eventually supplement the Galileo system. A significant disruption came in 2021, when the United Kingdom, following Brexit, withdrew its regulatory approval, meaning British pilots could no longer legally rely on EGNOS.
Global Peers, Budget, and the Ground-Access Challenge
EGNOS is one of four major satellite-based augmentation systems operating worldwide. North America relies on WAAS, Russia on SDCM, Japan on MSAS, and India on GAGAN. Together with Galileo, EGNOS received a combined budget of €14.6 billion for the 2021–2027 research and development period, underscoring the scale of the European commitment. While the system is primarily designed for aviation—where geostationary satellites provide an unobstructed line of sight even at very high latitudes—ground users face a practical limitation. In central Europe the satellites sit only about 30 degrees above the horizon, and in northern regions the elevation drops even further, making reception in urban canyons unreliable. To bridge this gap, ESA released SISNeT in 2002, an Internet-based service that streams EGNOS correction data continuously to ground receivers. The Finnish Geodetic Institute built the first experimental SISNeT receiver, and the company Septentrio later developed commercial versions. On the satellite side, PRN 136 entered the Operational Platform in August 2018, while PRN 120 moved to the Test Platform the following day. In practice, horizontal positioning accuracy reaches the metre level, well beyond the seven-metre specification.
Frequently Asked Questions
What is EGNOS in the GPS/satnav world?
EGNOS is a European satellite-based augmentation system built by ESA and Eurocontrol for the European Commission. It sits in geostationary orbit and overlays raw GPS signals with correction and integrity data, making positioning noticeably more reliable for users across Europe.
How does EGNOS actually improve a GPS receiver's position fix?
A ground network of 40 Ranging Integrity Monitoring Stations continuously tracks GPS signals, checks their reliability, and computes corrections. Those corrections plus integrity alerts are then broadcast back to users through three geostationary satellites, tightening the fix to metre-level accuracy in practice.
When did EGNOS go live and get certified for safety-of-life use?
Initial operations began in July 2005, and the system reached full official operational status on 1 October 2009. It earned its safety-of-life certification in March 2011, clearing it for aviation and other critical applications.
What horizontal accuracy can EGNOS users expect?
The system's specification calls for horizontal positioning accuracy better than seven metres, but real-world performance typically lands at the metre level. That level of precision is what makes it viable for certified, safety-critical navigation tasks.
What is EGNOS V3 and why should fans care?
EGNOS V3 is the planned next-generation upgrade that will extend the augmentation overlay from GPS alone to also cover the Galileo constellation. In practice, that means European users will get a more resilient, multi-constellation correction service rather than relying on a single satellite system.
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