A compass calibration is in progress

What ArduPilot says:

• PreArm: Compass calibration running

A compass calibration has been started and is still collecting samples, or waiting to begin. While it runs the offsets are being worked out afresh, so arming is refused. This check cannot be skipped.

What to do, most likely first

1. The calibration is still open in the ground station, or the ground station disconnected in the middle of it.

   FixFinish it (turn the aircraft until the bar is full) or cancel it. If the ground station is gone, reboot the flight controller.

2. A transmitter switch with the compass calibration function (RCn_OPTION 171) is in its high position.

   CheckHigh starts a calibration 5 s later and repeats it until it succeeds; low cancels it.

   FixFinish the calibration, or move the switch to low.

Parameters to look at

Where to do it:Setup & Tuning Guide