Hi, We were out mapping a storm water channel around an industrial facility. The last mission was the South Eastern boundary witch passed very close to the plant. On approach to the plant the copter started to deviate from the auto path. I activated RTL and not being able to see if she was turning back, I switched the mode to Alt Hold and brought the hex home.

Hex makeup:

Pixhawk running 3.2.1

FrSky telemetry system checking temp on power and motors

KDE motors and ESC's


820mm center to center.

On reviewing the logs I see that both ublox NEO-8 Gps's shows errors in the time the route deviation started. The mag and backup shows the same increase in field.


I redid the mission with a backup quad running APM 2.5 and single ublux NEO6 GPS without any issues.

My question - Is it possible to have some sort of magnetic field from this plant interfere with the navigation sensors or is it something else that I missed.

Attached the log. If anybody can shed some light on this it would be great, thanks.


2015-06-20 14-24-17.bin

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • Moderator

    Hi Antonie, we've seen hectic RF and who knows what else around these types of facilities in SA, there are typically all kinds of Tx's pushing out watts of power so could easily be interference. At 50m AGL you could fly through all kinds of stuff.

  • the gradually increasing "circle" movement is related to bad compass data.

    it could be a local magnetic field, but a compass *can* be calibrated poorly, and yet fly apparently fine until heading is in a certain position.

    So you can do a few things: - check with the UAV, if heading is correctly indicated in the position of trouble.

    I would switch ti manual in the area, and turn to a landmark known to be north (check map), verify compass, same for east/west/south.   - if that work at any other place, but not there, - then you have a strong magnetic field nearby.

This reply was deleted.


gotham liked gotham's profile
Hiroki Tanaka liked Hiroki Tanaka's profile
Oct 13
Derrick Davies liked lisa TDrones's profile
Sep 23