Fenix 6 Pro Constant GPS Offset to the left #fixyourbasics

That didn't help. I am in North America. I switched the run activity GPS setting to "GPS Only" and then ran one of my usual 5 mile routes. The track was still consistently offset to the left.

Before starting I let the GPS "soak" for several minutes. Most of the route had a clear view of the sky, just a few trees and bridges.

Three watches this morning (just because I have some lying around) 945, F6, and 935. Two on the right arm, one on the left. No complaints from this morning. The F6 is the blue one worn on the right wrist which is on the inside. I was running left to right or clockwise around this 5.5km loop.

They must have different hardware compared to my one. I very rarely get a track look like that.

Yesterday I also tried GPS + GALILEO and that didn't make any difference either. The track was still offset to the left.

Very interesting. I looked at a couple of my recent Fenix 6X runs where most of run was on road, and yes, there is pretty consistent offset to the left. In comparison offset to the right is quite rare.

I have also looked at similar runs I did before with Suunto 9, which has exactly the same Sony GPS chipset. While Suunto 9 is a bit more wobbly in general, overall its track looks far more accurate in terms of following the actual path. There isn't a constant offset like I see in my Garmin 6X track.

I have a theory that the offset has something to do with Garmin's dead reckoning algorithm. From multiple observations I can tell that the "current" position lags behind by a few seconds, perhaps 3-5 seconds. But I notice that when I turn, the turn is applied to the "current" position immediately, which makes the recorded track start the turn too early and cut the corner. I don't know exactly how that makes the track get the offset to the left, but my suspicion is that is caused by asymmetry of different turn radius between left and right turns due to the fact the the watch is worn on the left hand. Either that or perhaps Garmin uses some imperfect formula and introduces some rounding errors. 

Perhaps there is something else but veering to the left seems to be influenced by movement. I observed several times that when I stop or move slowly the position seems to correct, but when I start running again it jumps to the left again, sometimes quite sharply.

Here are a couple of screenshots from my recent run. This one shows the position correcting and shifting again at stoplights, although I can't remember which track corresponds to which direction.

Here is a more obvious example. Notice how the track corrected a bit at the first crossing, but then moved to the left again, and then how sharply it moved to the left at the second crossing, presumably after I started running.

I totally agree that there is an offset to the left with the watch (6X for me) worn on the outside of the left wrist. Today I also wore my 5X+ on the outside of my right wrist for my dog walk. The 5X+ showed an offset to the right, typically equal to or greater than the left shift from the 6X. The 5X+ was also far less stable each time I stopped moving. Complain all you like about the 6 series, but it is better than the 5+.

6X is red. 5X+ is blue. Both watches were using GPS+GLONASS and were freshly synced and GPS soaked before starting. 

I also often see an offset to the left, although since I used the 'hack' I don't any longer (I posted differences with and without 'hack' here somewhere), pre-hack I'd be running over water not over narrow bridges, with wearing it differently, that is solved. Since then, I don't get the offset.

I looked at a number of my tracks from last few days, and the pattern of veering to the left is pretty consistent. It very rarely veers to the right, it is sometimes correct, and it veers to the left most of the time - often as far as another side of street.

But here's what interesting. I often run with my dog, and we often stop to let him do his business. When we stop the track snaps into the correct position, often with a visible zigzag. Then once we start running again it veers to the left again. So my conclusion is that the watch is capable of more accurate positions, but it is probably some sort of dead reckoning algorithm that makes it veer to the left. 

I looked at a number of my tracks from last few days, and the pattern of veering to the left is pretty consistent. It very rarely veers to the right, it is sometimes correct, and it veers to the left most of the time - often as far as another side of a street.

But here's what interesting. I often run with my dog, and we often stop to let him do his business. When we stop the track snaps into the correct position, often with a visible zigzag. Then once we start running again it veers to the left again. So my conclusion is that the watch is capable of more accurate positions, but it is probably some sort of dead reckoning algorithm that makes it veer to the left. 

silentvoyager said:

I looked at a number of my tracks from last few days, and the pattern of veering to the left is pretty consistent. It very rarely veers to the right, it is sometimes correct, and it veers to the left most of the time - often as far as another side of a street.

Try to wear the watch at the right wrist and you'll find a veering to the right. It's simply the direction of the antenna that make the difference.