Well this wasn't pleasant, especially since I thought I had a flawless Mavic. But here goes. Weather conditions: clear, few clouds, very light wind at ground level
Location info: Nothing around for 5+ miles, no metal structures, just pure wilderness



I'm 16 minutes into this flight and everything was going just fine. I'm descending to get a better shot of these rocks when suddenly the Mavic started drifting like crazy. You can see this in the video, the drifting started exactly at 0:11 seconds. It goes left, then backwards, then right.. then suddenly it indicates it lost GPS signal. But look, it still shows 15-17 GPS satellites.
First I let go of the sticks to observe what it was going to do. I saw that it was continuing to drift so I input some correctional controls. The Mavic wasn't playing nicely at all. Fortunately I've been flying quads for 5 years, so I didn't panic but instead slowly massaged it back home and landed it fine. It resisted the whole way back. Another oddity to me is that it was drifting in the opposite direction of the light wind. If I lost GPS in proximity to trees or rocks, it easily would've crashed since it initially didn't respond very well to stick commands.

Now, this to me is concerning. Why did I lose GPS signal in the middle of nowhere? What is more concerning is it shows 15-18 satellites, even with no gps signal. After landing, I restarted the Mavic, and still the same thing. Then I came home hours later, turned the mavic on again and it regained GPS, with only 7 satellites.

Unfortunately I'm grounding my Mavic until I find out why it did this and how to resolve it. Any Ideas?

Have you updated to the latest firmware?  It's very possible you have.  I don't have a Mavic in hand so I can't be of any more help, but you might want to start there.

Not sure if the logs will help at all.  As I've never owned a DJI product before I don't know if they're of any use to the end user, but could be helpful.

I have the very latest firmware, I updated it as soon as I received the Mavic 2-3 days ago.

Good thing it was in line of sight.  You would have lost it more than likely.  That is crazy.  

Can you share log data? Thanks

Visualkaos Posted at 2016-11-13 13:37
Good thing it was in line of sight.  You would have lost it more than likely.  That is crazy.

Nah as long as he has Distance telemetry + heading & some common sense, he would be able to get it back.

Wind Junkie Posted at 2016-11-12 18:59
Can you share log data? Thanks

Here you go:
http://healthydrones.com/main?share=JedxkC

Logger Posted at 2016-11-13 11:16
Nah as long as he has Distance telemetry + heading & some common sense, he would be able to get it ...

yeah thats true good point

Following this -- Still waiting on my mavic, but one thing i've noticed is that most of the issues people have posted seem to happen when VPS is on.  I also fly out in the middle of nowhere and I think for safety, I'm going to just disable VPS, which is sorta funny since it's supposed to be a selling feature :/

Also following this

That's weird that it can update the distance to home on the phone screen.  How would it know that?

CamStevens Posted at 2016-11-12 21:58
That's weird that it can update the distance to hone on the phone screen.  How would it know that?

Not only that, but in the log it also shows its full position movements AFTER it supposedly lost GPS

If you can download the DAT file from that flight and upload it to Dropbox and provide the link I will have the flight data analysis team analyze the flight Monday.
Also, what is you email you use with the GO app and I can analyze the flight from the server after you sync your flight records.

Also, that aircraft may have operated totally normal, did you look at the KP index for that day?
I see it had 17 satellites, but the signal strength was very weak and that put it into ATTI mode.
If looks like you were fly by the side of the hill and air turbulence was probably the factor of the aircraft being a little difficult to control.
Go to a park flat park on a day where the KP index is low, if you still experience a GPS loss, then you may  need to have the GPS replaced.
How many flights have you had, and is this the only time this has happened?
I'm thinking everything is fine and it was the KP index that degraded the signal.
Also, you do have have a GPS tracker or anything attached to the rear of the aircraft do you, the GPS is in the top rear of the aircraft.

Following......

DJI-Ken Posted at 2016-11-13 14:51
If you can download the DAT file from that flight and upload it to Dropbox and provide the link I wi ...

I thought DJI R&D said KP index has no noticeable effect? or was it something else that I'm confusing with?

leostark Posted at 2016-11-13 11:25
I thought DJI R&D said KP index has no noticeable effect? or was it something else that I'm confus ...

Yes I agree with you. Following this issue....

Did you calibrate the IMU after the firmware upgrade?

rick39 Posted at 2016-11-13 03:28
Did you calibrate the IMU after the firmware upgrade?

No calibration done on IMU, I haven't been prompted to do one.

DJI-Ken Posted at 2016-11-12 22:51
If you can download the DAT file from that flight and upload it to Dropbox and provide the link I wi ...

Hi Ken, here's the dat log for that flight: https://www.dropbox.com/s/gctoe9 ... 8-02-07%5D.DAT?dl=0

My email address with the GO app is stealthvic@yahoo.com

Also, one thing I immediately checked afterwards was KP index, it was 3 so seemingly low.
Including test flights, this was the 7th flight. All others no issues whatsoever with GPS. I have nothing attached to the aircraft, it's totally oem. Hope this helps!

Edit:  Wrong post.

DJI-Ken Posted at 2016-11-13 14:51
If you can download the DAT file from that flight and upload it to Dropbox and provide the link I wi ...

Ohh the mighty KP index again.
Maybe its just me, but my $10 UBLOX that can only lock onto 9-11 Sats at best of times never left me in the wild even on high KP days.
I'd say the KP thing is OF COURSE existing but can never cause stuff like this.

Thats just MY opinion but based on practical everyday observation with my el-cheapo GPS that i use in 3 of 5 copters.

Greetings,

Nils

Just wondering, does the phantom 4 have issue's with a certain level of KP index?  If no, why would this be a issue for the mavic then?

Mir Posted at 2016-11-14 00:21
Hi Ken, here's the dat log for that flight: https://www.dropbox.com/s/gctoe9spdcfveyi/DJI_ASSISTAN ...

I just emailed you the RC log file, add that to Dropbox as well.

nils_heidorn Posted at 2016-11-13 12:42
Ohh the mighty KP index again.
Maybe its just me, but my $10 UBLOX that can only lock onto 9-11 Sat ...

I personally don't think it's KP, for one.. the KP index yesterday was 3, which is normal. Also.. I would think that the number of locked satellites would drop, but it maintained 15-18 satellites and even logged its own path perfectly after reviewing logs.

I think it's either a one-off firmware issue, or I have a bad GPS unit somehow.

DJI-Ken Posted at 2016-11-13 17:21
I just emailed you the RC log file, add that to Dropbox as well.

Thanks! Replied with all the things you need. I'd love to get this bird back up soon.

For now I've grounded it, because my "usual" flying area is a small park with hills, lakes, and surrounded by homes.  Don't want to lose it already

Interesting Side note.. at 1:50 in the video, you can see it goes from Atti Mode to Opti Mode. It suddenly became much easier to fly, I guess since it used its downward cameras and sensors to stabilize the aircraft

nu3vVF6J0ojO Posted at 2016-11-13 11:56
Following this -- Still waiting on my mavic, but one thing i've noticed is that most of the issues p ...

I agree. Every issue I hear about somehow involves the use of the VPS. I mean, if you're flying safely, I don't see a need for the VPS anyways. I guess more accurate landings and obstacle avoidance is cool, but loosing control isn't. I'm not sure how the VPS is related to GPS in this case but I to am considering just turning off the VPS all together.

Had same exact problem. Filming very slowly in a big city, suddenly no gps from 14-17, instant drifting, I landed manually which isn't hard but risky if you're far away etc.

JFXMedia Posted at 2016-11-14 23:21
Had same exact problem. Filming very slowly in a big city, suddenly no gps from 14-17, instant drift ...

What you experienced was not a problem, the aircraft performed like it should.
You said you were filming in a large city, that probably blocked your satellite signal.

Just an update, yesterday I did a test run (without taking off), and let it stand for 25 minutes, it kept GPS lock the whole time.
Feeling a little more confident, this morning I took her up in the air for a full 22 minute flight, it kept GPS lock the whole time.

Wondering if this was some kind of one-off fluke? Still strange it would do that.

Mir Posted at 2016-11-15 02:12
Just an update, yesterday I did a test run (without taking off), and let it stand for 25 minutes, it ...

Sounds good, I did look at your flight from the GO app and normally you would regain GPS back. It is strange that it went out and pretty much remained out. I so see at the last few moments it pop into GPS and then out again.
If you've flown it again and it operated normally then it can be a fluke of possibly something or someone causing the interference during that flight that knocked out the GPS.
I am glad that you are a good pilot and did not panic and flew it hone in ATTI  mode.
I've sent the logs in and we'll see if anything unusual pops up.
It's up to you if you want to send it in, if you're confident flying in an open area in ATTI mode then I would just fly it and see if it happens again. Possible take the same route to see if you get the same interference again.

DJI-Ken Posted at 2016-11-14 10:36
What you experienced was not a problem, the aircraft performed like it should.
You said you were f ...

Unfortunately, it was a problem with the aircraft or remote, and absolutely zero percent user error. Being about 25 feet from the aircraft (to see it behave) on the edge of a major city with excellent satellites, no people around just a church, where I have flown about 11 times prior. I then flew perfect orbits around the church for 10 minutes after the issue with no issue. As I manually landed the freshly calibrated aircraft the camera started to shake like it had rabies. I can not move the sticks fast enough to imitate that shake, nor do the sticks technically have the ability to perform such movements. You are dead wrong mate. I wish you were right. I'm just too experienced to believe everything DJI spews on these forums.
This is not a user error, this is a manual FPV racer user with every consumer DJI drone to date, highly experienced, with an error with a inferior rushed product, error. Since then I have had one issue with the Mavic, in the middle of a field, with GPS loss, and a constant drifting to the left. Do you have a quick easy solution for that issue Ken ? My mavic drifts to the left slowly about 6 out of 10 flights. I've seen others on here also with this issue. Flying straight often means flying to the left in a slow slight but noticeble line. I have this very often.

JFXMedia Posted at 2016-11-15 22:32
Unfortunately, it was a problem with the aircraft or remote, and absolutely zero percent user error ...

You said you were filming in a big city so I was thinking you were flying between skyscrapers.
It may lose GPS if the flight controller detects an error and it will go into ATTI mode.
You said it was drifting so I think it's the compass causing it to go into ATTI mode as a deviation between the compass and GPS may throw it into ATTI.
Calibrate the compass again in a interference free area (make sure that you unfold the arms BEFORE you power on the aircraft) and make sure mo metal is around you (RC/phone on ground several feet away from you) then calibrate. If you still get errors then please call 818-235-0789 and send the aircraft in for evaluation.

Mir Posted at 2016-11-15 02:12
Just an update, yesterday I did a test run (without taking off), and let it stand for 25 minutes, it ...

I posted this to the other user and I want you to try the same.
Calibrate the compass again in a interference free area (make sure that you unfold the arms BEFORE you power on the aircraft) and make sure mo metal is around you (RC/phone on ground several feet away from you) then calibrate. If you still get errors then please call 818-235-0789 and send the aircraft in for evaluation.

I've seen cases where the user powered the aircraft on then unfolded the arms. Always make sure you unfold the arms before powering up (if you are going to fly).

DJI-Ken Posted at 2016-11-15 08:40
I posted this to the other user and I want you to try the same.
Calibrate the compass again in a i ...

Since I've received the Mavic, I've never calibrated the compass since I haven't been prompted. I'll perform a calibration for the next flight.

Is this recommended because tech reviewed my flight log?

I'm here because I searched for GPS loss on the Mavic mid-flight, since this is the very same thing that happened to me.

I was flying in Hawaii over the ocean (so perfect GPS conditions), with 18 satellites locked on (while shooting footage for this video: ), and the Mavic suddenly lost GPS just like in this video (with 18 sattellites still showing as locked) and started flying away pretty fast by itself.

I've barely regained control and got it back safely, but not without freaking out for several minutes. It's very concerning just how badly it drifts and loses its mind when it thinks GPS is lost (even though there are still tons of satellites locked on). If we assume GPS lock was lost on 3/4 of them, then it's the fault of the software for not showing the data properly so that we may act more appropriately. Otherwise, giving up on GPS entirely seems like a really bad choice - even weak GPS data would be better than ATTI.

This is why Mavic needs ATTI mode switch, so people can practice for the situation like this.

Glad this hasn't happened to me yet. Appreciate this as a cautionary tale though. The mention of the "KP Index" in interesting. Is it assumed that it is the user's responsibility to monitor this factor to prevent their Mavic from going haywire crashing into people and buildings? I don't see any mention of this in the manual. How could a novice be expected to have any awareness of such a thing?

is difficult to use the mavic in atti mode?

i saw your video and You brought the drone to the ground manually, very well

fansbb5b373a Posted at 2016-11-20 00:43
is difficult to use the mavic in atti mode?

i saw your video and You brought the drone to the groun ...

If it's relatively windy at the altitude you're flying, it can get tricky as your Mavic will immediately drift in the direction of the wind. It's hard to tell from the video, but I was crabbing it on the way back. Meaning, I was almost going sideways because of the crosswind.

Otherwise it's not that bad if you have some experience with quads. One nice thing with the Mavic is once you're close to the ground, the Optical sensors take over to stabilize your flight if you lost GPS. This came in handy as seen in the video.