Consistent single altitude drop during the training sessions

Well, my replacement 745 watch arrived and disappointingly the elevation error still persists, along with the Spotify playlist shuffle problem. So after two weeks of using my retired 30 watch, I now have somebody's old watch, that had a fault and was refurbished.

Once I remember to calibrate the watch, the elevation tracks have been near perfect, 

the watch barometer still records the sudden increase or decrease in elevation but not during your run.

@Donal interesting... I shall try to calibrate altitude before the runs and see how I go. I noticed that drops are less frequent lately and I wonder if it can be attributed to more stable weather in the mornings in the last couple months. When the issue was reported we were in the middle of the winter and we've had wild variations in the temperature and pressure... 

I have tried calibrate the altitude, but no difference.

I've gotten into the habit of checking the ABC widget on the watch fairly regularly, particularly in the morning. I check it at home, where I know the actual height and manually set it, rather than doing it by GPS. The biggest deviation from my actual height was 200+ meters, but in fairness to the watch, that seems to have been the outliner. As you can see from the screenshots I've shared, there has been those 'instant' changes in height and pressure, but would the watch not have them anyway on auto calibration (if it worked correctly) I honestly don't know if the watch senses pressure constantly or periodically? 

Currently my biggest gripe is the spotify snag. I really like the shuffle option on my playlists, as you get that unexpected kick from a quicker song during intervals. I nearly know my playlists off by heart and when you know the next song I tend to save myself for it.

Hi Donal, since this problem started in Update Version 10 or 11, I have always let the GPS "soak" for a few minutes before starting an activity and also calibrated by entering the known elevation at my house. However, this problem still comes back on some runs. Before Software Update 10 or 11, this never occurred in the 1.5 years of using this watch over 100s of runs.

Also, the other watches in this generation of garmin watches (FR 945 and Fenix 6) do not have this problem. There are many more of these watches in use by the public and nobody has ever had this problem.

This leads me to conclude, that this is not a hardware defect only affecting a portion of the FR745s. The reality is that all the evidence points to this being a software bug where an auto-calibration is happening randomly in the middle of activities. An instants offset of a 100+m in 1 seconds is not due to the barometer or altimeter having pressure fluctuations.

I am still hopeful that Garmin can move one or two of the original FR 745 programmers back-over to this product to find what auto-calibration is randomly happening in the middle of an activity. Because, after the elevation shift, the relative elevation is consistently spot-on, but at the same time offset to new wrong calibration elevation.

Hopefully one day soon a software update happens with the first bullet point being fixed random elevation drop during an activity problem. Time will only tell.

Happy Running...JS

JS you are totally right, until I've made downgrade to 10.40 the problem disappeared. 

Let's hope Garmin will fix it... 

L. 

I've tried recalibrating both the altimeter and barometer at the start of my run along the same route I've had altitude drops in the past. The drops typically occur within the first 1/2 mile of a run. After recalibrating they it still happened but further along in the run, 3.6-mile mark, rather than near the start.

This morning I also manually calibrated the watch before the run but with no luck - as @JS and lucas435 already pointed out it really looks like the watch autocalibration occurs randomly during an activity rather than at the beginning, when the GPS signal has been locked.

Well, I didn't calibrate the watch this morning and as you can see, another instant drop in elevation, so I'm at a loss as to what the solution might be, considering calibration works for some and not others.

I've contacted support again, different person this time unfortunatly, so will have to go through the whole process again. I won't be accepting a replacement 745 watch this time, so I've asked how much an exchange for a 255, fenix 6 (similar price to the 745) or the more expensive 955, will cost me