OK, I get it, if you move location by more than 50 miles, you "should" re-calibrate the compass. And, the app will notify you of that need if it senses an issue etc. Well, I flew in Casa Grande, AZ on Saturday last week, then Sydney, Australia on Monday - app did not tell me to re-calibrate the compass! I did not even think of it until I took off - I landed and then flew very slowly and carefully for a couple of minutes - all good. Now I am 250 miles north of Sydney. I will definitely calibrate before flying, but the obvious question is - should the app or the bird have noticed where I was????
I think that its pretty apparent that calibrating the compass should be rarely necessary. I bought my Mavic from Amazon and I think that the Mavic shipped from one of their warehouses in either the mid-West or East Coast. Have never, ever calibrated the compass and it flies just fine. Now think about that: The Mavic was built and checked out and calibrated in China; it was then shipped to a warehouse in the mid-West or East Coast; and then finally the Mavic ends up in my hands here in the San Francisco bay area. How did the people checking out and calibrating my Mavic in China ever know that this particular Mavic was going to end up in the hands of someone living in the San Francisco area and calibrate the compass appropriately for San Francisco's longitude and latitude? Or perhaps Amazon warehouse workers in the mid-West or East Coast took my Mavic out of its box and kindly calibrated the compass for me when they saw that this particular Mavic was going to by shipped to someone in San Francisco?
Of course, this is all ridiculous. My Mavic underwent a checkout and calibration process at the DJI manufacturing site or test building without the people there ever knowing or caring where in the world this Mavic was going to end up - and now that it's in my hands, the Mavic flies just fine.
I say forget about all this talk about having to re-calibrate the compass every time you move your location by more than 50 miles. If the Mavic says that there is a problem, re-calibrate. Otherwise, just forget about the issue and enjoy flying.