Wildly inaccurate location, distance and altitude when skiing

I have a Fenix 5X. It was fine when I got it almost a year ago. GPS accuracy is kind of meh, but whatever. After 9 months, I started having massive issues with location and altitude drift while skiing with no changes in settings (once a second, GPS only, not Glonass, since Glonass sucks on this watch and introduces a lot more error, both in my experience, and in the analyses I've read). Here's an example of how atrocious the altitude readings would be:

Garmin replaced my watch, and the new one is immediately just as bad, if not worse. In this example took the same chairlift 5 times and skied 5 different routes. I skied with someone with a Fenix 5S for the same 5 lifts and 4 of these runs. All of the high points (towards the bottom) should be identical, and mine are spread out by a little over a half mile, while hers are spot on. If I altitude correct in Garmin Connect, everything is fine, altitude wise, but the GPS drift is still so bad that the watch is essentially pointless.

In all of this error, I'll find that certain ski runs are just dropped entirely by the watch because it still thinks I'm ascending long after I've gotten off the lift, and sometimes it will think I'm still skiing downhill for minutes on the lift run back up.

More odd is that I run around 80 miles a week and never have any weird fluctuations in altitude in my runs. I get some annoying GPS issues with lost signals, rather inaccurate live pace, etc, but they're still nowhere near as bad as what I see during skiing. Any idea what could be going on here? Seems like both barometer and GPS are extremely buggy. Garmin keeps trying to suggest that it could be settings issues, even though it happened immediately with the new watch and my use of default settings, apparently to avoid replacing the watch. I'm getting frustrated enough that I'm considering ending my 10 years of use of Garmin GPS watches and switching to something else.

Sorry the pictures are so small. The forum seems to be throwing errors and heavily minimizing them... ciq.forums.garmin.com/.../1345560.png ciq.forums.garmin.com/.../1345563.png ciq.forums.garmin.com/.../1345564.png

0 cander49 over 7 years ago

I think I finally determined the primary skiing issue by studying the maps closely, and, believe it or not, all of the major error seems to be coming from the barometer. I had thought of the straight lines between ski runs as chairlifts, but they're actually just connecting the dots between what the watch incorrectly thinks of as separate ski runs, miscomputed based on the very wrong data from the barometer. Since the barometer is functioning very poorly, the watch often thinks I'm still traveling upwards and on a ski lift for several minutes into the run. Thus, it starts saving data for the run several minutes in and connects the dot from the bottom of the lift to somewhere partly through the run. This explains why the bottom of each ski run would be in the correct spot, but the top is always so inaccurate. A few times, it's looked like the chairlift has bent off from its initial straight path after partway through the run, and this appears to be coming from the few times that the watch has thought I'm still traveling downhill for the first few minutes of a ski lift; then, partway up the lift, it finally detected that I'm going uphill, and connects a straight line from there until it finally detects downhill travel again.

It appears that I've only noticed this in skiing because 10-20,000 feet of vertical in a ski day is so much more than what I get in running. It typically adds on something like 10-20% of the total altitude gained, but in running for which I've used the Fenix lately, 10-20% could be as little as 20' of error, and at most 200' of error. Sure enough, I do have altitude error on the runs from the faulty barometer, but it's just not something I would catch unless I'm looking for it because the average day's 50' or so of error isn't terribly much. The minor issues with running tracking are probably going to keep occurring with these watches because, frankly, the Fenix series doesn't have a very good GPS chip, but I can take care of that with a foot pod, which I do intend to buy once I have all of this sorted out with this one.

Garmin is now offering to replace with another refurb, and I'm trying hard to get them to give me a new one instead. If the first refurb had a heavily faulty barometer, which seems to wear out with use, I don't have a lot of confidence in the next one. After 5 watch purchases over the past decade (2 Forerunner 305s for more battery life than 1 would provide, a 110, a Fenix 5X, and a Fenix 5S for my wife), and given the fact that I bought this new, not refurbished, I think it's a reasonable request. I'll keep things updated if anyone is interested.

0 Former Member over 7 years ago

Hi. Have the same experience as you.

https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5x/1326484-altimeter-is-wrong-on-fast-decent

but I do not have this issue while running or biking.

best regards from Norway