How do I know that the compass is interfered?

[Th3DroneroGT]

Well, I ask this question because I have seen that in the DJI GO 4 I had an interference level of the compass, and I have seen that other drones indicate the level of interference that has the compass, my question is in DJI Fly how do you know that? because it never says an interference level that has the compass.

 

[sar104]

Very simple - before takeoff check whether the direction that the aircraft is pointing as indicated in the app agrees with the direction that it is actually pointing on the ground. If those agree then you are good to go. If not then either the compass is out of calibration or (more likely) there is a local magnetic field interfering.