Fenix 6X Sapphire - Problem with GPS Total Distance.

Buildings no, of course there are some but very low-rise.

Tree's I would say sometimes. But have a look here. I was running on the path to the left of the red line. 15m difference...

Or here it's just open field.

I get that same 10' or so difference in the trail and red line.  If you switch wrist, the orientation switches.  FYI

I experienced that GPS accuracy is more accurate when speed is higher. Could be this the reason? 

About altitude Fenix 6 and Swiss Topo Map gave you close datas so Fenix 6 is ok, 630 and rawn on Garmin Connect are wrong. 

About GPS accuracy I hope Garmin will make a fix can increase it. 

Also I am experiencing low GPS accuracy when speed is low. To be honest I tested also 935 together and also it had issues at low walking speed. 

Simone.01 said:

I experienced that GPS accuracy is more accurate when speed is higher.

That is true. It is not only a Garmin "feature" it is common for all GPS devices. The reason is that position errors due to accuracy issues becomes relatively smaller if the correct change in position becomes larger which is the case if you move faster. 

baselpower said:

But have a look here. I was running on the path to the left of the red line. 15m difference...

I don't say that you don't have accuracy issues but the may be other reasons why you aren't on track. Compare these two, from the same activity: https://connect.garmin.com/modern/activity/4450666479

In this case Google seems more correct but for other places it may be the other way around. 

nico_132 said:

On the other hand, when running in the forest I found the GPX data to show ALWAYS like 300m longer distance, although the signale does not look noisy at all. In addition to that, the GPX distance is also equal to the one my collegue has on his FR945.

Personally I would trust the distance calculated by the watch more than distance based on the GPX track. We all agree that there are accuracy issues, for some larger and for some minor but still accuracy problems. The watch saves the position every second without any algorithms for filtering errors. Some are so small that you won't even see them on the map. The distance on the other hand can be calculated using a series of positions and apply filtering and algorithms to get a more accurate distance.

As an example I have a trail run (single track in the forest) I do from time to time. The distance standard deviation is very small if I use the distance the F6 gives me but if I export the GPX tracks and load them into http://www.mygpsfiles.com/app/ I get a much larger standard deviation. 

TobiasLj Why are you so sure about this?

In my case the distance from the Garmin Connect exported GPX is clearly the right one. Matches the forerunner 630 distance and matches the distance the track is measured and sign-posted by the city.

Fenix6 and Garmin Connect distance is 500m too short.

Thanks for the hint with changing the map. What a difference on your screenshot, I try to check the next few times on my activities.

However if you look at this corner, it still looks bad on Here Maps (corner cut by almost 30 meters)