GPS Accuracy

If I may: when I do work outs on tracks like hofster, distance is accurate. Laps are between 390m and 410m, and overall total is consistent with number of tracks. 

Nevertheless, instant speed or pace is not accurate, which is an issue since I usually do interval trainings by this time. 

no gps is reliable on the track, because the algorithm ce calculates the gps signal transforming it into a route calculates a curved line in many segments. On the track, the GPS is unreliable like all city race routes that have many deviations. That's why many times the distance declared by the organizers who measured the route by hand and not with a wrist gps is never the same anyway this is my track of the Ravenna Marathon.

https://connect.garmin.com/modern/activity/4241519294

only 200m difference from the distance measured and validated by the athletics federation.

As you can see not the best layout on the map, but the route was really articulated, many times we ran on cycle paths that flanked the main road and about 1 meter from the houses, and as you can see from the track it seems that I run the houses, but in reality it was a cycle path and sometimes we ran into public parks so not the best route possible. I would say that the Fenix 6 did not behave very badly, it can certainly improve but it is not so bad.

Anyone have similar problems ? Fenix 6 saphire titanium, firmware 4.30. During run pace shown by watch was around 5:30-5:40 (6:30 for moments)  it never dropped less than 5:20, but every 1km lap average was around 4:30 and I know that I was really running like 4:30 (i can feel it, I am experienced runner). Other day during massive run I run 10km with pace < 4:00 (3:45-3:55) but during this activity pace shown by watch never dropped less than 4:20 and again every 1km lap summary was correct. It is impossible to train for me without correct pace. My old suunto ambit 2 never had problems like this. I bought my Fenix last week and during 5 running days there always were problems with showing the correct pace. During 25 laps of 400 m stadium same problem, distance mesaured correctly but live pace sucks. I have tried both using GPS+Gallileo and GPS+Glonass.

Hello 

Exactly the same here. 1km pace is correct, instant pace is useless. I explained it to french customer service, but until now, except start satellite acquisition earlier, no other solution...

Example of last week end, for a trail. live pace does not make any sense compare to average (white horizontal line). Nevertheless, track on the map is good enough, and pace per lap is accurate!

How does it look if you overlay altitude? Pending between 7 and 4:30 for a trail is normal for me, it depends on elevation, the surface and how technical it is. Conditions change often during a trail.

Well, it is not the point : live pace is totally inaccurate, average speed is correct. I know my usual pace, I know I haven't been below 6min/km. 

If you look at live pace in the graph, it cannot, from a math point of view, lead to such an average pace ... So there is no logic in the measurements.

Your are right, I haven't really thought about it before but I just did a quick check on one if my previous trail runs, https://connect.garmin.com/modern/activity/4174488226

I exported the original FIT file and converted it to CSV using the FIT SDK, imported it to excel and removed everything except the 1s records with data. There is a field, enchanced_speed (m/s) got the average and (correctly) converted it to pace. According to that I had 7:10 as average but according to GC I had 6:51, interesting... So the correct average for the graph should be 7:10 and not 6:51 but based on the total distance 6:51 is correct.

Next test was to get the laps (1k auto laps) out of the FIT file and the average of the average lap speed gives a pace of 6:41...