Galileo and GLONASS on the Garmin GPSMap 66s

Satellite pages from a Garmin GPSMap 66s showing the GPS and GLONASS status screens

The GPSMap 66 series are the first trail receivers from Garmin to use both the Russian GLONASS and European Galileo satellite navigation systems. On the Satellite Setup page, you have a choice of using GPS (NavStar) only, or GPS+GLONASS, or GPS+Galileo. The advantage of using Galileo or GLONASS with GPS is that you have more satellites in the sky, which improves the quality of your position fix, and increases the receiver's accuracy and ability to maintain a position fix with a partial view of the sky. Note the 10-foot accuracy in the above screenshots. In my location in northern Arizona, more GLONASS satellites are usable than Galileo satellites, but you'll need to experiment under your own conditions.