Does the Mavic Air have to be level during power on for IMU calibration?  The last DJI drone I flew was the Phantom 1 and it required to be on level surface on power up to properly do a quick IMU caliberation.  This is difficuly with the Mavic Air since the power switch on the battery is on the bottom.

No, not at power on.  When you do an IMU calibration, it will prompt you to place it in several different positions.  Just make sure it is on a level surface when you go through that procedure.

Hello and good day the.ronin. I am sorry to know that you are having issues in calibrating the IMU of your DJI Mavic Air. I will be posting an official DJI Tutorial Video on how to properly calibrate the IMU of the said drone. I hope this can help. Please keep us posted on the said issue for us to help you further. Thank you.

Thanks guys.  

With the original Phantom, you would also perform IMU calibration (remember those Colin Guinn how-to videos?  LOL) pretty much the same way you do today.  But you were also cautioned to power on the Phantom while it was on level ground so it could perform a "quick" IMU calibration.  There were two kinds of calibrations.  I don't think the Mavic Air does this right?  (And if not, then that answers my question as to whether you can power on the Mavic Air while, say, walking with it.)

Thanks Stephen but I do know how to perform the calibration itself.  Thanks though.