HELP Mavic Crash

khooper802 · May 18, 2018

So recently I've been flying my Mavic at my school for the news channel we have. Recently I took off, in my normal area and I get errors of flying in a class D Warning zone, the aircraft then starts to fly itself left towards the doors of my school just after take off. I then try to maneuver it back my way but it doesn't have any response. It then flew into the doors folding the top propeller in and luckily I was there to stop to props with my hand and catch it before any other damage could have been done. I have attached the video and flight log. If someone could help me out, thanks!

DJI Flight Log Viewer - PhantomHelp.com

ac0j · May 18, 2018

How windy was it? Looks like when it got above the building ( that you were too close to). It got blown over the direction of you brief stick input

chazzm · May 18, 2018

Seems like the AC may have been in Atti mode and drifted in as it was in sports mode!?

Simmo · May 18, 2018

No point speculating without seeing the logs.

khooper802 · May 20, 2018

ac0j said:
How windy was it? Looks like when it got above the building ( that you were too close to). It got blown over the direction of you brief stick input

Sorry for the late reply. But there was zero wind

khooper802 · May 20, 2018

khooper802 said:
So recently I've been flying my Mavic at my school for the news channel we have. Recently I took off, in my normal area and I get errors of flying in a class D Warning zone, the aircraft then starts to fly itself left towards the doors of my school just after take off. I then try to maneuver it back my way but it doesn't have any response. It then flew into the doors folding the top propeller in and luckily I was there to stop to props with my hand and catch it before any other damage could have been done. I have attached the video and will get the flight log later. If someone could help me out, thanks!

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Here is the flight log

khooper802 · May 20, 2018

I

Simmo said:
No point speculating without seeing the logs.

I have uploaded the flight log

Simmo · May 20, 2018

I think this is one for @sar104 I see compass errors and being in sport mode, resulting in a small stint in Atti, back to sport and crash.
If the compass check wasn't conducted on takeoff, then the AC may well have done its own thing as the FC tried to work out the compass error.
More analysis required by the experts.

khooper802 · May 20, 2018

Simmo said:
I think this is one for @sar104. I see compass errors and being in sport mode, resulting in a small stint in Atti, back to sport and crash.
If the compass check wasn't conducted on takeoff, then the AC may well have done its own thing as the FC tried to work out the compass error.
More analysis required by the experts.

Yeh, agreed, so why wasn't the compass error showing up on my screen in the video or during flight?? I've had compass errors before to but they never resulted in a crash or rogue drone, just to land.

erkme73 · May 20, 2018

If the aircraft was actually pointing in the direction as shown by the arrow in your video, then the stick input matched the direction it was moving. You applied right on the right stick - that would have made the aircraft go to the right if viewed from behind. If it was facing you, it would have gone left. Admittedly I haven't looked at the logs, but the screen recording shows the aircraft moving in the direction of the stick input.

chazzm · Jun 3, 2018

khooper802 said:
Yeh, agreed, so why wasn't the compass error showing up on my screen in the video or during flight?? I've had compass errors before to but they never resulted in a crash or rogue drone, just to land.

That would have been my question,, the App should have had all kinds of alerts going off, because with the flight log showing this and no on screen and audio alerts then you have something seriously wrong there!

Simmo · Jun 3, 2018

@sar104

InvisibleName · Jun 3, 2018

khooper802 said:
I

I have uploaded the flight log

Was the drone actually facing you, like the direction arrow suggests? If not, there’s your problem! The drone’s compass was 180deg out with its actual heading, usually caused by local magnetic interference. This causes all sorts of internal conflict between the various systems - this is much talked about elsewhere in this forum.

sar104 · Jun 3, 2018

Simmo said:
@sar104

It was such a short flight that there are very few data to work with. However, looking at the GPS-derived location data versus what the IMU was calculating, there is very poor agreement.

That strongly suggests magnetic interference at the takeoff location, and the aircraft was throwing compass errors before it even left the ground - I've no idea why anyone would go ahead and take off in that situation. My suspicion would be localized magnetic distortion from rebar in the ground.

khooper802 · Jun 6, 2018

sar104 said:
It was such a short flight that there are very few data to work with. However, looking at the GPS-derived location data versus what the IMU was calculating, there is very poor agreement.

View attachment 39334

That strongly suggests magnetic interference at the takeoff location, and the aircraft was throwing compass errors before it even left the ground - I've no idea why anyone would go ahead and take off in that situation. My suspicion would be localized magnetic distortion from rebar in the ground.

The only issue was that I never got any issues on my screen... I also took off from my hand since the ground was not level. I didn't see any reason to not fly considering there was no warnings

khooper802 · Jun 6, 2018

InvisibleName said:
Was the drone actually facing you, like the direction arrow suggests? If not, there’s your problem! The drone’s compass was 180deg out with its actual heading, usually caused by local magnetic interference. This causes all sorts of internal conflict between the various systems - this is much talked about elsewhere in this forum.

Sorry for the late response. But yes as far as I saw it was facing away from me like it shows. It then started to do what ever it did and then went behind me and I tried to bring it down till it crashed... Any chance warranty will cover this?

InvisibleName · Jun 6, 2018

khooper802 said:
Sorry for the late response. But yes as far as I saw it was facing away from me like it shows. It then started to do what ever it did and then went behind me and I tried to bring it down till it crashed... Any chance warranty will cover this?

Possibly, but I doubt it! If local magnetic interference caused this, it would be outside DJI’s control

InvisibleName · Jun 6, 2018

khooper802 said:
The only issue was that I never got any issues on my screen... I also took off from my hand since the ground was not level. I didn't see any reason to not fly considering there was no warnings

The thing is, you did! The drone was pointing in one direction, but the indicator on your app was facing the opposite direction -a sure sign that something was wrong

sar104 · Jun 6, 2018

khooper802 said:
The only issue was that I never got any issues on my screen... I also took off from my hand since the ground was not level. I didn't see any reason to not fly considering there was no warnings

Were you wearing a watch, or anything else possibly magnetic? In any case - the log indicates numerous warnings were displayed - I'm afraid that DJI will most likely conclude that you were simply not paying attention. No harm in asking though - DJI is somewhat unpredictable and inconsistent in its response to claims.

BudWalker · Jun 6, 2018

khooper802 said:
The only issue was that I never got any issues on my screen... I also took off from my hand since the ground was not level. I didn't see any reason to not fly considering there was no warnings

From your description the Mavic was sitting on the ground, powered up and then you picked it up to hand launch it? If so, it's likely that the compromised Yaw was obtained while sitting on the ground. Typically, the effects of rebar, etc in sidewalks, roads, etc. only extend 1 to 2 meters above the surface.So hand launching would have been clear of any geomagnetic distortions. But, the problem is that there is a delay in a compromised Yaw being corrected by a correct compass. It can take anywhere between 15 secs to a minute for the Yaw to be completely corrected.

The .txt shows that a compass error should have been displayed in the Go App. But, regardless, the scenario where Yaw is compromised due to a geomagnetic distortion usually doesn't cause a compass error to be displayed. The only indication you will have is that the red triangle heading indicator doesn't match the actual orientation.