My Mavic Air is due to arrive some time today and I was wondering if these systems need to be calibrated straight away or is this something that needs doing if you have issues?

According to the DJI tutorial videos both come calibrated at delivery: https://forum.dji.com/thread-130974-1-1.html

I would recommend calibrating the IMU on a flat surface after updating the firmware and NFZ database but the vision sensors will only need to be calibrated when the app tells you. I would also calibrate the compass when you arrive at your first flight location - ensuring that there is no interference in the area. The manual has been recently updated to do this with the compass and no longer wait only when the app advises.

ok, great. I take it the compass is done in the same way as my P3a was done?

After IMU calibration on my P3a it used to take ages to start up saying it was "warming up" is this still a thing with newer DJI drones or have they resolved this?

Hi, if there is no relative error message in the app, you can choose to calibrate or not.  But for my personal preference, I would like to calibrate them first, for the tutorials, you can refer to Wachtberger's link above. And compass is calibrated just like Phantom 3A does. Hope you enjoy your flight!

AirSnaps Posted at 2018-1-30 04:28
ok, great. I take it the compass is done in the same way as my P3a was done?

After IMU calibration on my P3a it used to take ages to start up saying it was "warming up" is this still a thing with newer DJI drones or have they resolved this?

Don’t calibrate IMU or Vision sensors, unless it asks you to. There’s no point unless there are specific issues. My compass sensor values were quiet high and I got a compass error after upgrading, so a quick compass calibration sorted that out.

The IMU in the Mavic range don’t seem to need the temperature to be stable after start up, so chilling the drone is not required.
Compass calibration is the same as others, anti-clockwise in the flying plain, anti-clockwise nose down plain.