I'm with scoot on this one. If you are several feet away you shouldn't have any compass conflicts with the chair. I launch within ten feet or so from my car regularly with no issues.
Also, do not startup or trust prompts for a calibration from or near the chair, see if it clears several feet away, first.
Better yet if you are getting clean startup indications, don't calibrate at all. I have never calibrated my compass, or imu with hundreds of flights ranging hundreds of miles apart.
Finally, worse case, you get a prompt that won't go away, have someone do it away from the chair or other metal influences so as not to set an inaccurate calibration.
Thanks Robert. I'm sure if your car doesn't interfere with it then my chair should be fine!