Lost GPS signal scare

[BudWalker]

There have been several GPS related incidents posted recently where the cause was a drop in gpsHealth. These incidents are characterized by an abrupt unexplained GPS loss and then a switch to ATTI mode.

Here are the analyses of a few of these incidents;

Why did it fly away?
Did I Have a Fly Away or Did the Drone Return to Home?

gpsHealth is NOT the same as numSats, but, instead a measure of gps signal quality. gpsHealth has a range of 0 to 5 and a value of 4 or 5 is required for GPS mode. In these incidents gpsHealth abruptly drops from 5 to 1 causing the switch to ATTI mode. If this were ever to happen to my Mavic it wouldn't fly again until it had been repaired by DJI.

 

[Freland]

Is there any update on the lost GPS-issue? I've experienced it a couple of times now. Pretty scary when the it drops GPS-signal (from full strength down to zero for 10-30 s) and starts drifting in the wind...Strange considering I've been out on completely open fields with no cause of interference (no electrical lines, cell towers, buildings etc.)

Any advice on how to best manage those situation best? The only reason I have been able to "save the situation" has been that Mavic has been above any potential obstacles...

 

[harfordhawk]

Is there any update on the lost GPS-issue? I've experienced it a couple of times now. Pretty scary when the it drops GPS-signal (from full strength down to zero for 10-30 s) and starts drifting in the wind...Strange considering I've been out on completely open fields with no cause of interference (no electrical lines, cell towers, buildings etc.)

Any advice on how to best manage those situation best? The only reason I have been able to "save the situation" has been that Mavic has been above any potential obstacles...

I have tried to raise the issue with DJI and all the forums, but DJI just says nothing.

 

[ksull72487]

Tip if you loose GPS it is harder to fly. More RC like. If it's uncontrollable recalibrate the Compass and IMU. That could be an indicator something is off as well. I agree ATTI mode needs to come back as a setting. You can try tin foil to to cover the GPS on the rear and also turn Downward VPS off. The aircraft will still use Sonar etc but it's more RC Like. Fly it if it hovers good! Fly it higher slowly and watch for major drift. If it drifts a lot you may need recalibration. Small amounts should be normal. This can be tested indoors as well but you'll need to get well above 8ft.


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[dewster]

GPS loss shouldn't happen out in the open. There's something going haywire. I couldn't accept civilian devices dropping reception at altitude. ATTI mode should be a selectable option in case GPS/Glonass is unreliable.


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[Bcooksy]

Add one to the lost GPS situation...
I've been flying a Phantom 3 Pro for a couple months now and have never seen this on my Phantom.
Got my Mavic about a week ago, flown it a handful of times without any problems, including the same area I was in today.
Flew fine for about 20 minutes. Then out of nowhere, lost GPS... After looking at the logs, there was no gradual signal loss, and in the 2 occurrences they still showed 15 satellites, just no signal.
So I brought it home took it down to about 4ft. At this point the GPS had come back. So I though I would just let it hover and for a minute and then started a slow creep to see what would happen. Then out of nowhere, lost signal again and drifted right into a building. I tried to control it but it was pretty much on its own path at this point. Luckily it was only about 1-2ft off the ground by the time it hit, but still sucks.

 

[agilealtitude]

Same thing happening here. Brand new Mavic. 3 flights. 2 of them experienced a loss of GPS signal for a minute or two, throwing me into ATTI mode in windy weather (not fun). Sport mode seems to be the culprit---not sure yet. Interestingly, when playing the flight back, I can see that there was no shortage of satellites (16+). When I got my GPS fix back, I tried active track, but the system told me I had too weak of a GPS signal to execute the mode. Should also note that in the very beginning of the flight my gimbal horizon was off...had to calibrate the roll by incrementing then decrementing a value to get it to restore to normal. Not impressed with the bird so far.

 

[BudWalker]

There have been several GPS related incidents posted in other threads recently where the cause was a drop in gpsHealth. I suspect the incidents being reported in this thread are also being caused by a drop in gpsHealth. These incidents are characterized by an abrupt unexplained GPS loss and then a switch to ATTI mode.

Here are the analyses of a few of these incidents;

Why did it fly away?
Did I Have a Fly Away or Did the Drone Return to Home?

gpsHealth is NOT the same as numSats, but, instead a measure of gps signal quality. gpsHealth has a range of 0 to 5 and a value of 4 or 5 is required for GPS mode. In these incidents gpsHealth abruptly drops from 5 to 1 causing the switch to ATTI mode. If this were ever to happen to my Mavic it wouldn't fly again until it had been repaired by DJI.

 

[harfordhawk]

There have been several GPS related incidents posted in other threads recently where the cause was a drop in gpsHealth. I suspect the incidents being reported in this thread are also being caused by a drop in gpsHealth. These incidents are characterized by an abrupt unexplained GPS loss and then a switch to ATTI mode.

Here are the analyses of a few of these incidents;

Why did it fly away?
Did I Have a Fly Away or Did the Drone Return to Home?

gpsHealth is NOT the same as numSats, but, instead a measure of gps signal quality. gpsHealth has a range of 0 to 5 and a value of 4 or 5 is required for GPS mode. In these incidents gpsHealth abruptly drops from 5 to 1 causing the switch to ATTI mode. If this were ever to happen to my Mavic it wouldn't fly again until it had been repaired by DJI.

I know you have said this in that past, the part about returning your mavic for repair. I agree that , to me, this shouldn't happen, but I would like DJI to acknowledge this as well. I don't like the idea of returning my mavic at my expense and waiting three weeks for them to tell me this is totally normal, then charge me to say that. yes it has happened to me as well, I am just hoping that DJI will say something. I can't get anyone to say it.

 

[agilealtitude]

My thoughts exactly. Update: just ran through 2 batteries and avoided Sport Mode all together. The issue DID NOT re-occur. The only goofy thing is that I was not able to use 'follow-me' mode due to a 'weak GPS signal' message. 22 satellites--makes no sense. My thinking is that DJI has their thresholds of tolerance set very high. Normally I would appreciate a very tight sensitivities, but in this case:

1) I never experienced this with my P3A...so why now with a model several generations more advanced?
2) Messing with flight stabilization by putting the drone in ATTI mode should be an absolute last resort. You can't tell me that all of the sudden the unit loses its entire GPS fix, only to recover a minute or two later, with no change in the number of satellites.

 

[harfordhawk]

My thoughts exactly. Update: just ran through 2 batteries and avoided Sport Mode all together. The issue DID NOT re-occur. The only goofy thing is that I was not able to use 'follow-me' mode due to a 'weak GPS signal' message. 22 satellites--makes no sense. My thinking is that DJI has their thresholds of tolerance set very high. Normally I would appreciate a very tight sensitivities, but in this case:

1) I never experienced this with my P3A...so why now with a model several generations more advanced?
2) Messing with flight stabilization by putting the drone in ATTI mode should be an absolute last resort. You can't tell me that all of the sudden the unit loses its entire GPS fix, only to recover a minute or two later, with no change in the number of satellites.

I have read that the 'weak signal' for followme, means the mavic says your phone or tab has a weak gps, which could make sense... I know my tab has a really poor gps.

 

[Freland]

I wrote to DJI and asked about the GPS-issue (also linking to this thread), only got this answer:

"Thank you for contacting DJI Technical Support.

For GPS signal lost, this issue may occur when there is magnetic interference. You can fly the aircraft in an open area. If this issue persists, We recommend sending your product for diagnosis and repair."

 

[TestPilot]

These posts do not give me confidence. At all.

I nearly lost my Mavic when it RTH at 30m and that was when I lost control of it and could only stare at it while it hovered up there in the sky.

I only regained control when it ran out of battery and was forced to land. During its descent, I regained control of it and managed to maneuver it to an open spot.

 

[DirkGently]

I wrote to DJI and asked about the GPS-issue (also linking to this thread), only got this answer:

"Thank you for contacting DJI Technical Support.

For GPS signal lost, this issue may occur when there is magnetic interference. You can fly the aircraft in an open area. If this issue persists, We recommend sending your product for diagnosis and repair."

When I had the issue I was in the middle of nowhere - a good 2 miles to even the nearest building.

But what may have helped is a compass calibration.

I calibrated mine and since then - about 5 or 6 flights - the issue hasn't occurred again.

 

[Freland]

I'll make sure to do a compass calibration next time I fly so see if it makes any difference..

But as TestPilot wrote, DJI's answer does not give me much confidence. To me it seems like they are ignoring the issue. A proper investigation from their side would have been appreciated (or some kind of official statement saying something)...

 

[Leigh]

I posted about the same issue too, new Mav first flight, repeated 4 times in a row , didn't calibrate yet as wasn't prompted too and mixed advice on waiting for warning or doing straight away , will try again at the weekend in new location , once without calibrating then again after calibrating


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[DirkGently]

I'd calibrate everything - compass and the IMU - at least once anyway. Then the compass just occasionally.

I have a suspicion the GPS warnings are really compass and GPS not matching warnings.

Anyway worth a go before sending it back to DJI.

I agree they should - or maybe they are - investigate these issues.

The Mavic has been more temperamental than my DJI Phantom 3.

Also I find it doesn't handle wind as well as the Phantom 3. You can fly but I always feel its struggling more than the Phantom 3 did in the same conditions.

 

[harfordhawk]

I really want to send mine back for 'investigation' but I have no idea what that means? Do I have to pay for such an investigation? And if they can't replicate it, then I probably have to pay even more, plus time. They really need to do something about it!

 

[DirkGently]

I really want to send mine back for 'investigation' but I have no idea what that means? Do I have to pay for such an investigation? And if they can't replicate it, then I probably have to pay even more, plus time. They really need to do something about it!

Do all the calibrations. Fly away in remote areas where no interference. And if you still regularly get the issue then I would say send it back.

 

[harfordhawk]

Do all the calibrations. Fly away in remote areas where no interference. And if you still regularly get the issue then I would say send it back.

Yes that is good advice. But I don't get the problem regularly, just that unknown time, when you would not expect it. When you have been flying in the same area for many flights with no problem, then Bamm you're all the sudden in ATTI mode... that is the part that shakes my confidence.