A little note on compass calibration

[and-sh]

In place where I fly the magnetic inclination is about 74 degree.
https://en.wikipedia.org/wiki/Magnetic_dip
So to calibrate compass correctly I should rotate model in vertical plane rather then in horizontal.
Ideally in the plane parallel to magnetic field vector.
p.s.
Moreover we have a magnetic anomaly here. It may change the magnetic declination in range 9-20 degree.
https://en.wikipedia.org/wiki/Magnetic_declination
https://en.wikipedia.org/wiki/Magnetic_anomaly
It is usual, you can check
https://wdmam.org/
The simplest way to check that magnetic declination is correct is the following:
Drive in 2 pegs at a distance of about 100m, monitoring their position using GPS.
It's easier to use simple directions, such as north-south or west-east.
Orient the model to the direction between the pegs and check the compass readings. They should match the ones set, since Inav uses the direction of True North.
https://en.wikipedia.org/wiki/True_north
If they do not match, you can use the following parameters to adjust them:
inav_auto_mag_decl
mag_declination
Pay attention that declination sets not in degrees

Current location magnetic declination in format. For example, -6deg 37min = -637 for Japan. Leading zero in ddd not required. Get your local magnetic declination here: http://magnetic-declination.com/ . Not in use if inav_auto_mag_decl is turned on and you acquire valid GPS fix.