Altitude correction and course

Freddy said:

What's wrong

Are the sensor openings free of dirt and sweat? Are the sensor openings protected from direct airstreams? Are the sensor openings not covered by clothing ?
Do you calibrate before riding? Which method do you use?
Here is a support article :

https://support.garmin.com/en-US/?faq=H6cKTJLhTF6mr7TZe0NRYA 

Thanks but as I wrote this is not the topic here (this forum is about Garmin Connect web). The issue is the difference between the corrected altidude (+ 1404 m) and the positive elevation (+ 1944 m) when i saved the course. 540 m of difference for the same course...

Freddy said:

But as I wrote this is not the topic

Freddy said:

My barometric altimeter is borken on my watch.

Freddy said:

My watch registered 15404 m of positiv elevation.

If you think the sensor is not working properly, the first step should be to troubleshoot THIS problem.

I did

Freddy said:

The issue is the difference between the corrected altidude (+ 1404 m) and the positive elevation (+ 1944 m) when i saved the course.

Like I said. If the watch has problems detecting the air pressure change correctly, this can lead to this.
It would be helpful if you could post a link to the offending activity. Or at least a screenshot of the recorded altitude profile.
Is it possible that this profile shows many small spikes? These would all affect the altitude meters.

Yes, that's why I asked you to publish the recorded elevation profile.

Freddy said:

Then i saved this course and Connect showed me 1944 m of positiv elevation !!! What's wrong Garmin ?

Different resolution results in different Elevation Gain. Activity saved as Course does not keep the same way points as the original activity. It repositions and optimizes their number. That can easily result in a quite different calculated Elevation Gain.

Yes you are right but Garmin could do something to show more or less consistent results... Or they specify that the positiv elevation is not accurate on Garmin Connect web.

Freddy said:

Or they specify that the positiv elevation is not accurate on Garmin Connect web.

I would not tell that it is not accurate, unless you can prove it by exporting the course file, importing it into Excel, calculating the elevation gain there, and get a different number. If it is that case, then please report it to the Product Support through their website at https://support.garmin.com and send them both the original course file, and your Excel spreadsheet showing the difference.