D2 Charlie Altimeter / Vertical Speed <-> Aviation Units BUG

This issue has already been added to the bug list by dbrobert, see https://forums.garmin.com/forum/on-the-trail/wrist-worn/d2-series/1312355-d2-charlie-version-4-00

I got a new D2C last week. I am having an issue with the accuracy of the altimeter. I noticed that the Altimeter is approximately 250 feet off when calibrated using the barometric pressure obtained from the nearest METAR. I was at the airport the other day and I can confirm this issue. I understand that I can calibrate it manually but I just wanted to see if anyone else has experienced this issue.

This issue has already been added to the bug list by dbrobert, see https://forums.garmin.com/forum/on-the-trail/wrist-worn/d2-series/1312355-d2-charlie-version-4-00

Yes. And it has been here right from the beginning (at least v2.90 as far as I can tell). It'd be nice if acknowledged by Garmin itself!

I got a new D2C last week. I am having an issue with the accuracy of the altimeter. I noticed that the Altimeter is approximately 250 feet off when calibrated using the barometric pressure obtained from the nearest METAR. I was at the airport the other day and I can confirm this issue. I understand that I can calibrate it manually but I just wanted to see if anyone else has experienced this issue.

Same here. Enable the Barometer widget and look at its calibration settings: you can set both the altimeter and the corresponding barometric pressure (QNH ?), thus "calibrating the instrumental error". Since then, the Altimeter - once calibrated with the actual altitude - has given me barometric pressure that match the current QNH quite closely (I expect calibrating it the other way around, thanks to METAR, ought to work better too).

Garmin again:
That being said, it'd be nice if the Altimeter could also be calibrated manually (not though METARs) using a known barometric pressure (QNH).

(rant)
It is appears the devs of the D2 know nothing of aviation and let pass the most glaring problems/inconsistencies.
Sad given with the price of the gadget...
(/rant)

I have a D2 Charlie now and have been working through the reported bug list and compiling my own list, including the issues with Garmin Pilot and with the auto-import feature of the FlyGarmin logbook. I've already reported a few additional issues, but I will make sure I put the full list together after the next release (overdue now) and send it to the D2 team.

Cheers,
Douglas

The altimeter does not seem to catch-up with the changing elevation quickly enough...see my recent flight: https://connect.garmin.com/modern/activity/2766486656
The airport elevation is roughly 1000 feet. I had the autofly mode enabled (500 fpm) which started recording after some distance after I took off. I was at least 1500 feet by that time it started recording..but it is showing as 1053 feet. Same thing when I landed...it is showing the altimeter as roughly 2000 feet when I touched down... I noticed some similar conversation going on in the fenix 5X forums as well..hopefully, garmin will fix it when they fix the similar issue with the 5x.

The altimeter does not seem to catch-up with the changing elevation quickly enough...see my recent flight: https://connect.garmin.com/modern/activity/2766486656
The airport elevation is roughly 1000 feet. I had the autofly mode enabled (500 fpm) which started recording after some distance after I took off. I was at least 1500 feet by that time it started recording..but it is showing as 1053 feet. Same thing when I landed...it is showing the altimeter as roughly 2000 feet when I touched down... I noticed some similar conversation going on in the fenix 5X forums as well..hopefully, garmin will fix it when they fix the similar issue with the 5x.

I think I might have the explanation for this behavior:
Go to the *Barometer Widget* settings and verify the "Watch Mode" is set to "Altimeter". If it is set to "Auto" (the default, if I recall correctly), the watch attempts to work both as an altimeter and a barometer (...): if pressure variations are small enough, they are considered barometric pressure change; if pressure variations are fast enough, then they are considered altitude-pressure change. Of course, as an aviator watch, we want to make sure it behaves as an altimeter only, and not some weird mix of pressure-related instruments :-/

I think I might have the explanation for this behavior:
Go to the *Barometer Widget* settings and verify the "Watch Mode" is set to "Altimeter". If it is set to "Auto" (the default, if I recall correctly), the watch attempts to work both as an altimeter and a barometer (...): if pressure variations are small enough, they are considered barometric pressure change; if pressure variations are fast enough, then they are considered altitude-pressure change. Of course, as an aviator watch, we want to make sure it behaves as an altimeter only, and not some weird mix of pressure-related instruments :-/

Thank you. I will give that a try. Did this work for you? One would assume that Garmin already incorporated this when FLY app is started.

The altimeter does not seem to catch-up with the changing elevation quickly enough...see my recent flight: https://connect.garmin.com/modern/activity/2766486656
The airport elevation is roughly 1000 feet. I had the autofly mode enabled (500 fpm) which started recording after some distance after I took off. I was at least 1500 feet by that time it started recording..but it is showing as 1053 feet. Same thing when I landed...it is showing the altimeter as roughly 2000 feet when I touched down... I noticed some similar conversation going on in the fenix 5X forums as well..hopefully, garmin will fix it when they fix the similar issue with the 5x.

This bug is also here for Fenix 5X that i owned (and i suppose 5) : https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5x/1326484-altimeter-is-wrong-on-fast-decent , and Fenix 5 Plus that i own: https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5-5s-plus/1366374-here-we-go-again-altimeter-is-wrong-on-fast-ascent , i'm reporting this bug since months but nothing... please report this bug you too...

Another report: https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5x/1366982-elevation-errors-after-update-to-9-20-from-8-00

Thank you renton82. I sent an email to Garmin Aviation support. I will post if I hear anything from them. It looks like the issue is widespread.

Firmware updated to 4.20 (double-checked with Garmin Express and rebooted the watch twice): both issues reported in original post are still present (despite changelog mentioning a fix in this respect to the Altimeter widget).