garmin fenix 5x plus altimeter issues

Does your travelling include aircraft?

Had my 5x Plus replaced in warranty two times, but mine showed +/- 40000 meters. As it was explained to me by Garmin Italy Support, the watch will normally show the altitude +/- 50 meters, being a barometric altimeter. You can contact your local Garmin Support, explain them the situation, send them pictures or video when the altimeter is acting up, maybe they will replace it, but for that "minor" difference of altitude, if I were you, I wouldn't be bothered by it. If the weather is changing constantly, it will affect the altitude readings. Try to set it to auto calibrate when not in an activity and continuously calibrate during an activity, maybe that will help you. I would recommend, when you calibrate it manually, to do it only with DEM, that will use the topo map, that is more accurate then the GPS.
Hope that helps, I used a defective unit for almost 6 months, drove me crazy. :)

If you move 150 km away from where the watch was calibrated, the air pressure even at the same altitude can be quite different at the new location. So during your travel, the pressure will change, both because your probably travel through different altitudes, and because you travel through different pressures at the same altitude.

The watch will to a certain extent try to guess the reasons for the changed pressure, but it will only be a guess, so when you arrive, the altitude can be quite wrong, and you will have to do a new calibration. That is just the nature of how a barometric altimeter works. The only way you can solve it completely is by moving to another planet with a fixed relationship between altitude and pressure.

Try to set it to auto calibrate when not in an activity and continuously calibrate during an activity, maybe that will help you. I would recommend, when you calibrate it manually, to do it only with DEM, that will use the topo map, that is more accurate then the GPS.

Thanks for your input and tips i will try that setting :)

If you move 150 km away from where the watch was calibrated, the air pressure even at the same altitude can be quite different at the new location. So during your travel, the pressure will change, both because your probably travel through different altitudes, and because you travel through different pressures at the same altitude.

The watch will to a certain extent try to guess the reasons for the changed pressure, but it will only be a guess, so when you arrive, the altitude can be quite wrong, and you will have to do a new calibration. That is just the nature of how a barometric altimeter works. The only way you can solve it completely is by moving to another planet with a fixed relationship between altitude and pressure.

Thanks for your input. Even though i don't like it, it sounds logic. I guess i missed the detail regarding the watch that is was a barometric altimeter :eek:

I have the same problem but when i start an activity. I always calibrate beforehand and then during a short 10km trail run where i go from sea level to 400m then down again i end up Couple of 100m before sea level Also annoying during 100km runs i have to recalibrate several times to correct the altitude Tried suggestions above and switching off the barometer but same issue.
??????Shall I take it back? fenix5x+ is only 6 months old

Had my 5x Plus replaced in warranty two times, but mine showed +/- 40000 meters. As it was explained to me by Garmin Italy Support, the watch will normally show the altitude +/- 50 meters, being a barometric altimeter. You can contact your local Garmin Support, explain them the situation, send them pictures or video when the altimeter is acting up, maybe they will replace it, but for that "minor" difference of altitude, if I were you, I wouldn't be bothered by it. If the weather is changing constantly, it will affect the altitude readings. Try to set it to auto calibrate when not in an activity and continuously calibrate during an activity, maybe that will help you. I would recommend, when you calibrate it manually, to do it only with DEM, that will use the topo map, that is more accurate then the GPS.
Hope that helps, I used a defective unit for almost 6 months, drove me crazy. :)

Yes, but you have to watch on place where you make DEM calibration. if it is during climbing (via ferrata or tower type of climbing / wall climbing) DEM can give you wrong information.

you can also see topics here:
https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5x-plus/1448200-problems-with-altimeter-barometer-settings-for-mountaineering-and-skiing
https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5x-plus/1406115-alimeter-issues