Hi,

Wonder if DJI Ken or DJI Mindy may be able to answer a question or two, took the Marvin the Mavic to the Beach this morning, a fine sunny Northumberland day, all well sunshine, light winds. I had not carried out a compass calibration as I was not far away from where I carried out the last one.

All started off well, until Marvin decided that he would switch to ATTI Mode, 17 GPS Sats. but only one red 'bar' - see photo. Bit of panic set in, but plan B carried out and flew back in hand, landed, took this screenshot:

Changed battery and had another go, everything started out OK went off to photograph the surf, decided, for no other reason than I wanted to try it - Initiated a RTH, it started out OK then it got quite exciting as Marvin again switched to ATTI mode, which stopped RTH from his end, but the controller continued to tell me it was returning to home, pressing the Home button, helpfully displayed the message 'No RTH' but the controller continued to beep annoyingly.

Marvin was now with the wind, always with a plan B continued to fly the aircraft manually back home, this turned ito a bit of a struggle as my inputs seemed to be sporadic and it made controlling the aircraft quite difficult. I had added to this difficulty by climbing to give seperation between the cold North Sea and the aircraft, while I worked out a course of action.

I continued to fight the aircraft back to home, where it suddenly switch back to P-Mode & finally the controller stopped beeping and I was able to bring Marvin home.

In the hover I looked at all the sensor data all well nothing unusual, then he decided to draw circles in the sky! the dreaded TBE, I let it go for a few seconds but the osscilations got very large! Time to land.

Another battery fitted and this time a calibration of the compass carried out, flew again, no problems.

In summary looks like the problem was to do with compass/GPS data conflict, there were no errors recorded that I can see during the flight. The sensors revealed nothing unusual but the behavior was strange, the RTH was a little stressful but no harm done and everyone is safe!

I would ask that DJI review my logs email same as my forum login, from 2nd of January and see if there is anything that would give more information as to the behaviour and possibly confirm my thoughts that the compass was possibly the culprit.

I am after clarification as I think the drone is a fantastic bit of kit presence of mind got me home, the only scary bit was when the aircraft had given up on return to home, which I can cope with, but the controller seemed to be continuing to tell me it was returning to home while displaying a very confusion message of 'No RTH'.

Aanything else you need please ask.
DJI Go 4 for iOS
iPhone 7+
Uptodate Firmware (29/12/16)

Eek. Glad you got it back. I thought the firmware update was supposed to fix the dilution of precision issue. You can be connected to many satellites but still not have a good position fix. Interested to see how this turns out.

justflie Posted at 2017-1-2 14:15
Eek. Glad you got it back. I thought the firmware update was supposed to fix the dilution of precision issue. You can be connected to many satellites but still not have a good position fix. Interested to see how this turns out.

Yeah I suspect that this may be down to a Compass & GPS conflict. I understand that the Mavic will always favor the compass for heading data over GPS, as the earth magnetic field can't be turned off(!)

It would be useful if there was a specific message to covey this situation rather than just switching to ATTI mode and showing 17 Sats and showing a degraded signal. Maybe something like 'GPS/Compass conflict - Calibrate Compass' as essentially you know if there is a heading difference between what the compass is resolving and the track resolved by the GPS unit.

I would rather have that than the annoying 'Wind' message.

Yeah mine does the same thing... I received mine maybe a week ago and out of the 20 flights I've done... calibrating compass and imu... I've only been able to actually fly it with no gps issues twice..: all other times gps was lost mid flight and carried away with the wind and having to be faught to get it back. Honestly on the verge of returning it. I'm in Hawaii and I don't exactly want to go on a hike and have the drone crash into a mountain because it lost gps.

NSRacin_Oahu Posted at 2017-1-4 02:31
Yeah mine does the same thing... I received mine maybe a week ago and out of the 20 flights I've done... calibrating compass and imu... I've only been able to actually fly it with no gps issues twice..: all other times gps was lost mid flight and carried away with the wind and having to be faught to get it back. Honestly on the verge of returning it. I'm in Hawaii and I don't exactly want to go on a hike and have the drone crash into a mountain because it lost gps.

To be honest this is the first time I have had any problems with it and have flown 20 or so flights, in open space, in trees. this experience was the first time I had any issues. I suspect its a compass calibration issue, DJI have my flight logs I am just waiting for them to be checked.

Safety first