ianwood
Taco Wrangler
The problem with the suggestions to not recalibrate the compass is, when the app gives a compass error your choices are to recalibrate or not fly because it won't allow the motors to start until a successful recalibration is complete. Unfortunately this happened so often for me I considered it routine. It now seems to me that the app could be better designed by providing a "magnetic interference" warning instead of simply prompting to recalibrate. IMHO
Other than calibration, you have to choose the right take off point. If you're getting an error on a good calibration before take off, you're trying to take off in the wrong spot. If you're getting an error in the air, either your calibration is bad or you're close to a significant source of interference.