Magnetic Declination Possible Issue/Question?

Hi guys.

I am seeing possibly something strange with the declination info inside the compass menu and I am not sure if there is something wrong or it is the way it is supposed to act. With automatic declination learn checked, then do a compass calibration, it is usually 1-3 degrees off from my location actual declination.

Also, if I uncheck the automatic learn declination box and manually type in the actual declination for where I am flying then go out of the compass menu and back in the compass menu it changes the declination to something totally different even though I manually put the numbers in. Is this normal? Should the magnetic declination be reading very close to my location’s magnetic declination from a website like this ?

Thank you.

I thought this issue was addresses already or maybe you are looking for more opinions.

No, I think my mag anomaly problem has been solved with disabling the internal compasses and redoing the compass calibration…thank you.

With regards to this post on declination is why I am getting almost 3 degrees off and when I try to manually type it in it does not save my numbers and goes to a completely different number. Just trying to understand if this is the way it is supposed to be or not? Almost 3 degrees off seems high and manually typing in my actual declination of my location is not saving and going to a different number.

Hoping someone can help.

It says in the docs that I should be getting less than 1 degree, but I am not getting that. I believe these numbers are hard coded in and should reset if you have the learn or automatic declination box checked on startups.

I then have tried to uncheck and manually put the numbers in, but it does not keep my numbers and changes to usually at least a degree of what it should be. Not sure what to do or what is right?

I know that they are hard coded in the firmware. Not sure how often they are updated. Copying @dkemxr he may know the answer.

They are hard coded and they don’t have to be updated often as declination change is very low over a relatively long period of time. I thought I read that it was updated recently. For example near where I am:

Look at the tolerance. +/- 24 years worth of change…

If you are at the North Pole its a much greater change.

Ok, thank you Dave.

I will do another flight today and see what number the automatic declination brings up.

I guess I do not understand unchecking the automatic declination box and typing the declination in manually when it does not keep your number and changes it to a different number?


It should store it if you are using internal compass. Not sure about external…

Have u tried this method?

Tuning declination in-flight

Although we do not believe this is ever necessary, you can manually tune the declination in flight using the Channel 6 tuning knob on your transmitter by following these steps:

  1. Connect your Pixhawk (or other board) to the Mission Planner
  2. Go to the Software | Copter Pids screen
  3. Set the Ch6 Opt to “Declination”, Min to “0.0” and Max to “3.0”. This will give a tunable range of -30 to +30 degrees. Set Max to “2.0” to tune from -20 to +20 degrees, etc.../_images/CompassCalibration_TuneDec.png
  4. Check the declination is updating correctly when turning the channel 6 tuning knob to it’s maximum position, go to Config/Tuning | Standard Params screen, press the Refresh Params button and ensuring that COMPASS_DEC is 0.523 (this is 30 degrees expressed in radians)../_images/CompassCalibration_TuneDecCheck.png
  5. Fly your copter in Loiter mode in at least two directions and ensure that after a fast forward flight you do not see any circling (also known as “toilet bowling”).
  6. If you find it’s impossible to tune away the circling then it’s likely you will require an external compass or GPS+compass