Wrong distance with Ultratrack mode

When GPS is not active (like it is the case most of the time when using the UltraTrack mode), the watch uses the accelerometer data (basically the cadence) to estimated the distance. For that to work properly, the watch must have been already calibrated with a run minimally 2km long in the standard GPS mode, and with a GPS signal of a good quality.

Alternatively, you can use the HRM-Pro chest belt, and enable the option for providing the pace & distance data "always". After having it calibrated in normal GPS mode, of course too. Once calibrated, disable the auto-calibration option to prevent the calibration gets skewed during UltraTrack activities. The data from the strap will be much more accurate than from the watch self.

Another option is using the RD Pod, which can do the same too.

... and to fix the distance of the activities already recorded, if you have also a Strava account, you can use for example Strava's option "Correct Distance" (in the web version only) - it will recalculate the distance using the available GPS data, instead of using the internal data from the accelerometer. Once you get the corrected distance, you can edit the activity in Garmin Connect, adjusting the distance accordingly. Another option is saving the activity as Course, and viewing the map distance at the saved course. Or exporting it as GPX, and using one of numerous online GPX viewers to get the distance.

this is a software bug, people opened tickets for it incl. myself and so far no fix; it used to work before 8.6x software just fine.

(not going into discussions with mr. trux here, please)

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/instinct/307572/problem-with-ultratrac-mode-for-hiking

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/instinct-2-series/305067/instinct-2-activity-distance-completely-off-charts-like-300km-too-much/1474844#1474844

and it's more threads on the same, hope this will get fixed some time

9820003 said:

this is a software bug, people opened tickets for it incl. myself and so far no fix; it used to work before 8.6x software just fine.

Yes, the GPS-less distance calculation was changed a few months ago, in the way I described. And I guess Garmin's developers did not take in account potential problems in UltraTrack mode. However, I bet that if you calibrate a HRM-Pro in the standard GPS mode, then disable the auto-calibration, the UtraTrack will then report the correct distance. Did you try that?

I try it without HMR-Pro (I do not have any) but does not work for me... But maybe the GPS signal was not good enought...

Standa said:

I try it without HMR-Pro

Without HRM-Pro you cannot disable the auto-calibration, and I suspect that the previously calibrated data gets overwritten also during the UT (which I admit should not happen, and if it is really so, then it is a bug). So unfortunately, there is no easy way to test the calibration without an external sensor like the HRM-Pro, RD Pod, Stryd, or similar, where you can enable, disable, or even reset the calibration. I will do some tests this week in UT without my HRM-Pro, and post the outcome here.

OK, so I just did two tests now with UltraTrack mode on my Instinct 2. The first one with the HRM-Pro, and the second one without it. Both of them recorded the distance perfectly accurately. That confirms what I wrote previously - all you need is properly calibrating your watch by doing a few runs with the standard GPS mode on.

If it does not help alone, you can also try calibrating the Treadmill activity profile. Never mind if you do not have any treadmill - you can do it by running on a known track outside. Just start the Treadmill activity, run minimally 1.5km or 1 mile, and at the end select the option Calibrate in the saving menu (if not suggested automatically). 

And if you use the UltraTrack mode rather at walking or hiking, make sure to calibrate the watch with the appropriate activity profile selected (and with enable full GPS mode, of course).

I have recieved my Garmin Instinct 2 watch yesterday. 

I went running for 11km with normal GPS mode and it was accurate, version was 4.02. 

Then I came home and updated watch via Garmin Express to version 10.10, GPS and other things were updated too. I factory reset watch and set everything to my liking.

In the morning I went hiking 8km as I usually do. I set Hiking to UltraTrac mode. In the end I got 18km. First km was ok and then it started, sometimes I made 10 steps and it reported 1km. I don't remember my Forerunner had that problem with UltraTrac, I mean it wasn't as accurate but it was maybe 200m different from normal GPS mode.

I went hiking again in afternoon and 3.5km walk was recorded as 8km.

So if I understand I have to walk or run few times with normal GPS mode and then try with UltraTrac?

I uploaded photo, you can see between 2 and 3km and 4 and 5km.

Distraneurin said:

I factory reset watch and set everything to my liking.

If you factory reset the watch, you also erased the previously done calibration. You need to calibrate the watch first in normal GPS mode, in order to have it working in UltraTrac

Thank you. I will try and report back in few days.