Between the wind, the cold temperatures, and the foul weather, conditions really haven't been good for flying, so I've spent a bit of time reading the manual, and familiarizing myself with the camera and the menu system. But at least I have been able to calibrate the IMU and the compass. Both were calibrated without issue. I calibrated the IMU indoors and went out in my back yard away from any metallic structures to calibrate the compass.

Today when I turned the mini on to play with the camera, I received a compass calbration error that told me to move the mini away from metallic objects (I forget the exact wording). The metallic object in question was the leg of the coffee table on which the mini was resting. OK, I understand that part. What I don't understand is why that error showed up after calibration and what suddenly made it so sensitive to that coffee table leg? It's not the first time I've rested it in that spot (but it probably will be the last), but it is the first time I've received an error while doing do.

Fortunately I wasn't flying when I received the error but it would be nice to understand why my mini suddenly got so sensitive. This whole thing would make more sense to me had I gotten the error the first time I placed the mini on that table.

I will definitely go outside and calibrate the compass again when this freezing drizzle stops. Will I also need to recaiibrate the IMU at the same time just to be on the safe side?

Hello and good day Tervist. I am sorry for the trouble this has caused and thank you for reaching out. It is recommended that the compass of your DJI Mavic Mini is calibrated in any of the following situations when flying outdoors : First, flying at a location further than 31 miles ( 50 km ) away from the location the drone was last flown. Second, The aircraft has not been flown for more than 30 days. Third, a compass interference warning appears in the DJI Fly and/or the aircraft status indicator blinks read and yellow alternatively. Just a reminder that do not calibrate the compass in locations where magnetic interference may occur, such as close to magnetic deposits or large metallic structures such as parking structures, steel reinforcement basements, bridges, cars, and scaffolding. Do not carry objects ( such as mobile phones or smart watches ) that contains ferromagnetic materials near aircraft during calibration. Thank you.

DJI Stephen Posted at 12-13 13:23
Hello and good day Tervist. I am sorry for the trouble this has caused and thank you for reaching out. It is recommended that the compass of your DJI Mavic Mini is calibrated in any of the following situations when flying outdoors : First, flying at a location further than 31 miles ( 50 km ) away from the location the drone was last flown. Second, The aircraft has not been flown for more than 30 days. Third, a compass interference warning appears in the DJI Fly and/or the aircraft status indicator blinks read and yellow alternatively. Just a reminder that do not calibrate the compass in locations where magnetic interference may occur, such as close to magnetic deposits or large metallic structures such as parking structures, steel reinforcement basements, bridges, cars, and scaffolding. Do not carry objects ( such as mobile phones or smart watches ) that contains ferromagnetic materials near aircraft during calibration. Thank you.

This is a different set of DJI's recommendations regarding compass calibration (50km difference in location and 30 days "refreshment" period) than what most of veterans is accustomed to. Seasoned pilots of Phantom, Inspire or Matrice drones will avoid frequent compass calibrations as much as possible. Is it because new generation of Mavic drones is using different, more advanced compass technology?

DJI Stephen Posted at 12-13 13:23
Hello and good day Tervist. I am sorry for the trouble this has caused and thank you for reaching out. It is recommended that the compass of your DJI Mavic Mini is calibrated in any of the following situations when flying outdoors : First, flying at a location further than 31 miles ( 50 km ) away from the location the drone was last flown. Second, The aircraft has not been flown for more than 30 days. Third, a compass interference warning appears in the DJI Fly and/or the aircraft status indicator blinks read and yellow alternatively. Just a reminder that do not calibrate the compass in locations where magnetic interference may occur, such as close to magnetic deposits or large metallic structures such as parking structures, steel reinforcement basements, bridges, cars, and scaffolding. Do not carry objects ( such as mobile phones or smart watches ) that contains ferromagnetic materials near aircraft during calibration. Thank you.

Thank you for your reply, Stephen. My mini is brand new and was shipped from China, and I'm definitely more than 31 miles from there, and since it's new it has yet to be flown. I calibrated it outdoors away from metallic structures, automobiles, magnetic deposits, my iPhone, etc.

The error occurred after a successful calibration and in a situation/place where no error had occurred until today. I am curious to learn why that error happened after a successful calibration and not prior because I'd had that mini sitting in the same place on several occasions prior to calibrating it.

It's not a problem yet because weather conditions have prevented me from flying, but I would appreciate some insight into why this error happened.

Matthew Dobrski Posted at 12-13 15:15
This is a different set of DJI's recommendations regarding compass calibration (50km difference in location and 30 days "refreshment" period) than what most of veterans is accustomed to. Seasoned pilots of Phantom, Inspire or Matrice drones will avoid frequent compass calibrations as much as possible. Is it because new generation of Mavic drones is using different, more advanced compass technology?

Hello and good day Matthew Dobrski. Thank you for reaching out and for the information you have shared with us. The DJI Mavic 2 series drones are designed to have dual IMU and single compass. It is best to perform two rotation calibrations by rotating different axis. That is to say, no matter if the aircraft's nose faces upward, downward, to the left or right, make sure that the gravity vector is on different planes during the first rotation and second rotation. ( For example, rotate the drone around the z-axis for the first rotation and rotate the drone around the x-axis for the second rotation. ) for a safe and reliable flight. Thank you.

Your correct you should always calibrate compass outdoors, but likewise you should always calibrate IMU at normal outside temperatures.
It not necessary to calibrate IMU outside but my advice is to leave drone outside for 40 minutes then bring back inside to calibrate.
Reason for this, when starting craft before flight you IMU will need to adapt to the temperature it’s in, if you calibrated in a warm room you will have to wait for IMU to warm up to this temperature before you can take off, so best to calibrate to normal outdoor conditions outside and it will engage quicker.

DJI Stephen Posted at 12-14 13:39
Hello and good day Matthew Dobrski. Thank you for reaching out and for the information you have shared with us. The DJI Mavic 2 series drones are designed to have dual IMU and single compass. It is best to perform two rotation calibrations by rotating different axis. That is to say, no matter if the aircraft's nose faces upward, downward, to the left or right, make sure that the gravity vector is on different planes during the first rotation and second rotation. ( For example, rotate the drone around the z-axis for the first rotation and rotate the drone around the x-axis for the second rotation. ) for a safe and reliable flight. Thank you.

Stephen, you don't understand my concerns. My confusions is not about compass calibrating procedure, which is well explained in manual. Is it why Mavic's compass calibration requirements are different than these stated for Phantom or Inspire class drones? No issue, just plain curiosity ...

Tervist Posted at 12-13 15:17
Thank you for your reply, Stephen. My mini is brand new and was shipped from China, and I'm definitely more than 31 miles from there, and since it's new it has yet to be flown. I calibrated it outdoors away from metallic structures, automobiles, magnetic deposits, my iPhone, etc.

The error occurred after a successful calibration and in a situation/place where no error had occurred until today. I am curious to learn why that error happened after a successful calibration and not prior because I'd had that mini sitting in the same place on several occasions prior to calibrating it.

You are very much welcome Tervist and thank you for the additional information you have shared. Kindly please to calibrate the compass properly once again and see if the issue will still persist. If the issue still persist then it is best to contact our DJI Support Team at https://www.dji.com/support?site=brandsite&from=nav for further assistance on this matter and for us to be able to check the said drone completely. Thank you.

If you get a compass error moving the craft  near to an object that disappears when you move away from it  , then that's fine. Many things will upset it- most electrical devices will distort the local magnetic field.
But hidden problems occur with large things. Paving containing rebar or iron  affect a large area.

The problem occurs if you calibrate  actually in such an area of interference  and the compass registers that as correct. Then everywhere else is detected as an error and disaster follows.
As the craft flies out into the different magnetic field it receives compass info that  says its changed direction, but the imu has recorded no inertial movement or control input to confirm this ,and it all conflicts with the direction of travel derived from the gps data, and all goes pear shaped.
I still don't understand how 2 compasses or a 'redundant' can help since they will both be similarly affected by interference and therefore equally compromised.

For first time I had this error "compass calibration error" while at flight about 50m above me but when I bring it back when it is close to me the error went off and fly it back I had the error again. Landed and recalibrated fly again had the error again. Any advise ? Hardware issues or software? never had this issue before. Safe to fly with the error ?