Compass calibration error

Squiddley · Oct 14, 2015

Went out for a fly the other day did a compass calibration before flight took it up everything looked good said safe to fly calibration worked like it should but after taking it up maybe 100 feet up and 75 feet out get a compass calibration error start to bring it back compass calibration error dissapears and goes back to safe to fly flew it for the rest of the battery flew great no problems anyone have any idea why this would have happened

BudWalker · Oct 14, 2015

Squiddley said:
Went out for a fly the other day did a compass calibration before flight took it up everything looked good said safe to fly calibration worked like it should but after taking it up maybe 100 feet up and 75 feet out get a compass calibration error start to bring it back compass calibration error dissapears and goes back to safe to fly flew it for the rest of the battery flew great no problems anyone have any idea why this would have happened

I recently figured out how to extract raw magnetometer data from the FLYXXX.DAT file. It may help determine what happened in the flight. If you post the FLYXXX.DAT I'll extract the info and give you back a CSV file.

Meta4 · Oct 14, 2015

Squiddley said:
Went out for a fly the other day did a compass calibration before flight took it up everything looked good said safe to fly calibration worked like it should but after taking it up maybe 100 feet up and 75 feet out get a compass calibration error start to bring it back compass calibration error disappears and goes back to safe to fly flew it for the rest of the battery flew great no problems anyone have any idea why this would have happened

Most likely explanation is that you calibrated in an area where the earth's magnetic field was distorted by a lot of steel nearby (reinforcing in concrete perhaps?)
Calibrating there corrects for this distortion so the compass adjusts for it.
When you fly further away and the distortion no longer affects your Phantom, the compass now doesn't point north because it is adjusting for the effect of the steel which is no longer there.
Another reason why calibrating every flight can be a bad thing.