EGNOS, the European Geostationary Navigation Overlay Service, is now live. Launched on Thursday, the system is designed to improve the accuracy of GPS in Europe. Chartplotters or GPS units bought over the past few years are nearly all WAAS/EGNOS compatible, but until now only WAAS (launched in 2003) has been active, limiting the greater accuracy afforded by these systems to US waters.

Basic GPS accuracy stands at around 7 metres, but where the antenna only has a few satellites in view can be significantly worse than this. EGNOS provides a system of 34 ground stations whose signals can be used to improve the accuracy of a GPS fix to 2 metres or less.

For marine users this may mean little more than being able to see your boat perfectly aligned with a marina pontoon on the chart, but for other industries the results are potentially far-reaching. EGNOS dramatically improves the accuracy of vertical as well as horizontal positioning, to the extent that it could now be a viable input to automatic aircraft landing systems, while road users will welcome the ability of the unit to distinguish between roads running closely together – there is even talk of using it to inform you if you are driving in the wrong lane. New applications may also include aids for blind pedestrians.

EGNOS is a first step for European satellite positioning, and the precursor of the EU-funded Galileo project, which is jointly run by the European Commission, European Space Agency and the aviation authority Eurocontrol. Currently expected by 2014, Galileo aims to have a network of satellites in place which is entirely independent of the US-controlled GPS system and also of any military interests.

What should I do next?
If you have an older, non-EGNOS-enabled unit your GPS will continue at the same accuracy as before. Many owners of more modern units will see an immediate improvement in the accuracy of their position fixes, while other may need to enable EGNOS through a software or firmware update. Check the instruction manual and, if in doubt whether EGNOS is working, contact your dealer for advice.

For more details, visit www.esa.int