Fenix 6 "GPS + Galileo + Elevation Auto Calibration" altitude problem

sylr over 5 years ago

Hi,

I did a general aviation Flight with both my Polar V800 (purple) and Fenix 6 Pro (orange) to compare things.

In terms of altitude it does not look good for the Fenix 6.

As you can see the altitude started to decrease when I leveled after the initial climb ...

I did another flight with only GPS and Elevation Auto Calibration disabled and things were better.

Have you also noticed discrepancies while using Elevation Auto Calibration or Galileo ?

Top Replies

C.sco over 5 years ago +5 verified

The auto-calibration is definitely NOT for aviation use!

It uses your GPS location, and compares it with the DEM file in the watch (ie, it figures out what the ground-surface elevation should be at your…

All Replies

0 GJRodenburg over 5 years ago

Might it be trying to get the calibration down to ground-level? It has these altitude maps on board, and might calibrate on those (not taking into account that some of us step into planes :)

0 Former Member over 5 years ago

sylr

thank you for sharing

happy & safe sporting

+1 C.sco over 5 years ago

The auto-calibration is definitely NOT for aviation use!

It uses your GPS location, and compares it with the DEM file in the watch (ie, it figures out what the ground-surface elevation should be at your GPS coordinates, and if it doesn't match the barometer sensor reading, it gradually shifts the barometer reading one way or another until eventually they align.) That gradual shift toward the ground-surface elevation is exactly what you're seeing in your first chart.

Auto-calibration is designed for ground-surface travel only - if you use auto-calibration in the air, it will cause your altitude reading to gradually drop until finally it thinks you're at ground level.

The only solution for this is to turn off auto-calibration when you're using it for aviation. It's not a bug or an error in the watch - your watch is doing exactly what it is designed to do.

0 sylr over 5 years ago in reply to C.sco

Thanks!

I assumed the auto calibration was done with the GPS altitude rather than the DEM data.

0 Davesen over 5 years ago in reply to C.sco

Do you really know, that DEM file is used for auto calibration or do you only suggest it will be used?

0 C.sco over 5 years ago in reply to Davesen

auto-calibration during activity definitely uses the DEM file, according to the Fenix online manual. Garmin says it also uses GPS elevation in addition to the DEM file, but really it doesn't seem to use GPS elevation at all, which is probably a good thing since GPS elevation is only accurate to +/- 400 feet, according to Garmin. So it probably only uses GPS elevation as a fallback if it can't use the DEM file for whatever reason.

0 Simone.01 over 5 years ago in reply to C.sco

I am very happy to read that but I did not find it in the manual. Could you send me the link of the online manual page where you found it?

0 C.sco over 5 years ago in reply to Simone.01

https://support.garmin.com/en-US/?faq=Vdz7RVePPV7wm1gO2d46TA

0 Dr Phil over 5 years ago in reply to C.sco

But that's for the 5 plus series...

Sorry just had to say that before somebody posts a negative comment about the link :-)

0 sylr over 5 years ago in reply to C.sco

"GPS elevation is only accurate to +/- 400 feet, according to Garmin"

Can you point out where you saw that statement ?