GPS LOST ATTI MODE AND RC DISCONNECT

Mavkeb · Feb 25, 2018

Ok so had my MP for about 60 faultless flights.
On FW .400 and never updated because it worked flawlessly.
Today I flew it about 300m away from where I live at a mates new place.
Got home point set. Took off and hovered. Checked home point again. Took it up to about 30m to get some video. Then all a of a sudden just took off in atti mode with the RC disconnected. It had 17 Sats but NO GPS.
It flew in a straight line to a position over 500m away. I had no control. I had no RTH or pause button, it just kept going. Eventually it picked up a GPS and because no connection it did RTH to the correct location where I landed it.
On the flight log it looks like it lost GPS and thought it was in a different location and tried to correct itself by flying back to that false position. The red triangle for the AC jumps from where I was to this random position 500m away instantly.
Luckily it was at a height that was high enough not to hit anything.
Any ideas?
Bad compass/imu?
Why would you lose GPS with 17/18 sats and the controller all at the same time?
Really worried to fly again now.
Will do compass and IMU cal first though.

Mavkeb · Feb 25, 2018

Here's some screenshots

petruce · Feb 26, 2018

I had the same problem I had gotten the litchi app to do some waypoint missions and on my first mission the drone flew to the first and second waypoints fine but when it went to the third waypoint it turned towards the fourth waypoint and started flying sideways I wondered why it was flying sideways to the next waypoint when I looked at the controller and saw that it had gone into atti mode and was drifting away . I tried RTH three times and no results I next hit the pause button and it stopped, and I was able to fly it back to me. After looking at the flight information I saw where I had 17 sats at the time when I went into atti mode and right before I hit pause I had regained GPS. The next day I flew 2 more waypoint missions with no problems.

Rustybeats · Mar 1, 2018

Mavkeb said:
Here's some screenshotsView attachment 32208 View attachment 32209

Hey mate,

Same problem here, never got my Mavic Air back after it flew away. There were no obstacles but started in into mode. After take off it suddenly changed to atti mode, which I can fly in normally. But once it got up to 30 metres, she just flew far far away.
DJI responded by saying it was a user error. Good luck flying it next time... I have no drone anymore!!!

Roger Eads · Mar 1, 2018

Rustybeats said:
Hey mate,

Same problem here, never got my Mavic Air back after it flew away. There were no obstacles but started in into mode. After take off it suddenly changed to atti mode, which I can fly in normally. But once it got up to 30 metres, she just flew far far away.
DJI responded by saying it was a user error. Good luck flying it next time... I have no drone anymore!!!

Roger Eads · Mar 1, 2018

Sorry to hear mate. It is that type of nightmare scenario that caused me to attach a tracking device to my drone. I use a Marco Polo. It allows tracking up to 2 miles.

GerdS · Mar 1, 2018

The error "GPS lost" is misleading. The Mavic almost never looses GPS except in environments where parts of the hemispere are shielded e.g. by buildings or other obstacles.
For working in GPS mode the IMU always needs to know Mavic's nose direction from the compasses for calculating the motor actions needed for either holding position or flying in the commanded direction. If it detects that the taken motor actions don't lead to the expected position change, e.g. because the compasses are delivering false data, the Mavic will fall back into Atti mode, which looks same as if GPS reception has failed.
I have read (but never tried) that in such situations one can do an emmergency compass calibration by rotating the Mavic around its yaw axis for several times. This should result changing into GPS mode again.
In rare cases it may happen that the Mavic will disconnect from the remote controller. I have seen this happening in some cases caused by USB problems between remote controller and GO4 app, where the transmitter was hung up with frozen display. If this happens, don't hesitate with powering off and restarting the remote controller. It will automatically reconnect to Mavic then.

Mavkeb · Mar 1, 2018

Rustybeats said:
Hey mate,

Same problem here, never got my Mavic Air back after it flew away. There were no obstacles but started in into mode. After take off it suddenly changed to atti mode, which I can fly in normally. But once it got up to 30 metres, she just flew far far away.
DJI responded by saying it was a user error. Good luck flying it next time... I have no drone anymore!!!

Sorry to hear you weren't so fortunate.
I have recalibrate IMU and compass but we have bad weather (6 inches of snow) just now so haven't had chance to fly since.
Will post back if she does it again. Be great to get some snowy footage.

I have also read that spinning it round 360 a few times can get your GPS back.
If it happens again I reckon the safest bet is to try that first if you can, and maybe power cycle the remote to ensure that disconnection will trigger RTH but without GPS it can't RTH and will just try to land wherever it is so that could be dodgy too if you can't see it.

Still not 100% sure if it disconnected, the app froze or I just panicked when it went ATTI for no apparent reason (never lost GPS before) but I know now that the No RTH is because it had no GPS but should the pause button work? I definitely hit that a few times. It seemed to be going too fast to be just drifting with the wind.
The flight log showed 17 or 18 satellites the whole time it was going AWOL.

Rustybeats · Mar 2, 2018

DJI is reluctant to assist or at least acknowledge that the disconnect was not due to pilot error. All they are saying is to mind your environment. Which in my case had little interference with the drone.

It did get 7 gps signals just before leaving me forever. Reckon this would be covered under warranty?

56_kruiser · Mar 2, 2018

Roger Eads said:
Sorry to hear mate. It is that type of nightmare scenario that caused me to attach a tracking device to my drone. I use a Marco Polo. It allows tracking up to 2 miles.

I've been considering getting one. Those burgers ardent creation. But certainly less than a new drone.

ScubaBob · Mar 2, 2018

From reading other postings I have found that it is best to take two minutes before EVERY flight and recalibrate your compass. It can't hurt and at least you can "check the box" that you did that. Once a month or so I recalibrate the IMU, too. That is about all I can suggest.

LIMavicPilot · Mar 2, 2018

a DJI employee told me to not do that.. he said that it introduces the chance of doing a bad calibration (calibrating with interference) and almost guaranteeing the Mavic going into atti mode.

ScubaBob · Mar 2, 2018

I don't agree with that. If you select a location in an open area with no metal around it should do no harm and if you follow the simple DJI instructions it is nearly impossible to screw up. My Garmin GPS requires compass calibration on a regular basis and my compass app on my iPhone does as well. I can't believe that calibration of the compass on a regular basis is not a good idea but I will be interested to hear what others suggest.

LIMavicPilot · Mar 2, 2018

Personally, I hope you are correct.. Id rather know that we can all just calibrate our compass and minimize a flyaway risk rather then to just cross our fingers whenever we fly.

56_kruiser · Mar 2, 2018

It makes good sense to me. I think the comment from DJI is probably valid in that people do tend to get in a hurry and get lax. So it certainly could be possible to not pay attention to your environment . Bottom line we need to be diligent in thinking

GerdS · Mar 2, 2018

DJI is right, no good idee doing calibration too often.
In some cases it can become more worse than before. Do it if you have changed location for at least 100 miles, if GO app asks to do, if your Mavic has been exposed to strong magnetic fields, or if you experience your Mavic drifting around while hovering or after stopping from speed flight.

MavicCF · Mar 2, 2018

ScubaBob said:
From reading other postings I have found that it is best to take two minutes before EVERY flight and recalibrate your compass. It can't hurt and at least you can "check the box" that you did that. Once a month or so I recalibrate the IMU, too. That is about all I can suggest.

I've also heard that compass calibrations are unnecessary unless prompted by the DJI Go app. If you recallibrate every time the likelihood of having something go wrong is higher than just doing it once in an ideal environment.
I personally have never calibrated my compass and have had zero issues with anything related. I could be wrong but that's what I've learned. -CF

Vegasdad · Mar 2, 2018

This happened to me but only lasted 4 minutes. I tried to keep my head on and focus on my map and reading to start it back home. The problem I think was because I traveled from LV to SD and I know better but again got in a hurry trying to catch something fast. Nothing is that important to not take your time... Lesson learned.