My 2 cents....
Having a background in Electrical/Electronic Engineering/digital circuit design and working with INS on Navy ships and aircraft like the F15 Eagle and F18 Hornet systems at McDonnel Douglas, I am still dumbfounded that it even works. From the Navy’s SINS gyro rack that weighs hundreds of pounds to today's quartz rate sensors using microscopic tuning fork gyros that weigh fractions of an ounce just makes your head hurt. (there are now in development nano gyros making the latter look gigantic)
I am also a private pilot and as any student pilot soon learns about that floating compass hanging off the windscreen, magnetic north ain’t north! The Earth’s geomagnetic field changes continually, the poles shift and even altitude distorts the dipolar nature of the field. You learn to use marked charts, the compass placard showing how your specific aircraft affects you compass and even your altitude, to correct you compass heading. And, once you do all that, 100 miles from here you get to correct it again because it’s changed.
Looking at some of the comments made, there are many angles presented on why this error happens. Some a technically advanced but there is an easier explanation.
- Bad cables; doubt it. if everything else is working, the very nature of how data is transmitted on that connector precludes that. There isn’t any wire dedicate for compass.
- Buried cables; doubt that. They would be low power lines (220 vac); doesn’t generate enough field and most of these tiny circuits is shielded just for that. No High-Power lines underground.
The “mag interference” is PLANET EARTH. As a pilot must re compensate for magnetic progression, so does your bird. Most of these devices can store information over some period of time on the chip using capacitive charges (like mini batteries). If the last flight remembered north and it now senses too much progression, it’s mag interference (you moved it). I’m sure the programmers were just looking to save a few bytes on what they thought were useless characters in memory, so we get a generic error.
The F15E Eagle introduced Ring Laser gyro design to come up immediately so they could scramble an alert. But if the ground crew moved that bird to the other side of the tarmac, you will wait for it to re-calibrate, including external device stimulus to help it “find itself”.
Holding your Mavic flat and turning 360 then rolling it on its side and turning it another 360 is a massive recalculation helping that lost compass re-find its way to the North Pole … (Occam get's it).
