GPS height accuracy

Former Member over 5 years ago

I have a Fenix 5. On Sunday I ran 4 miles and then turned around and ran 4 miles back. This was along a country road so no talk buildings. There were a few trees but no woods or forests. The height results showed a 60 foot difference between start and finish. I started and stopped at the same place. I ran a similar route 2 days later at 4.5 miles and saw a 50 foot difference. Anyway to improve the accuracy?

0 AllanOlesen67 over 5 years ago

Your altitude doesn't come from GPS, it comes from the barometric altimeter in your watch.

Is this a Fenix 5 or a Fenix 5 Plus?

The Fenix 5 and the Forerunner 935 had some temperature sensitivity in the barometric altimeter, so you would get altitude drift for the first 10-20 minutes of a run if you came from a warm home and took a run in cold weather. (Or cold home / hot weather). But I haven't seen this happening with my Fenix 5X Plus.

Even if the barometric altimeter is working perfectly, you can also get drift from changes in ambient pressure during your run. But that usually happens rather slowly, and 60 foot during an 8 miles run seems as a quite rapid change (unless you run just as slowly as I do).