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Magnetic interferance-flyaway

job996

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#1
Problem? Flown in same spot for 3 weeks. Used up 2 batteries on the day and landed to put fresh battery in. Everything ok and took off. Within 5 second, the screen flashe breaking now, return sticks to midpoint, then continue flying. Then Magnetic filed interference came up and the drone took off and reach 17M/S and hit a tree. It was not in sports mode and there was absolutely no control.

Was unit in a crash? Yes

What have you tried so far? Sent it to DJI Australia and have only recieved a bill to repair it, nothing about warranty or replacement. No way of contacting them to find out what caused it. I uploaded the flight data for them to check as well.

What device are you using ( iphone , ipad, Samsung , etc)? Samsung S9

What firmware are you running ( aircraft, remote controller)? DJI Go 4

What Go app version are you using? Updated August 18th

Any modification?
(if so what) 2 weeks old out of the box

Did you change anything or install any apps? (if so what) DId an update on the Drone 2 days before and calibrated compass in a field free of interference.

Do you have a video or pictures of the problem? (if so post link) Attached picture


Question is, how do I get hold of the repairer to ask why I cannot get a replacement, as I believe this was a technical issue, not mine. I do not want a crashed dron back and have the same issue.
Thank-you in advance for any help.
 

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Meta4

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#2
Problem? Flown in same spot for 3 weeks. Used up 2 batteries on the day and landed to put fresh battery in. Everything ok and took off. Within 5 second, the screen flashe breaking now, return sticks to midpoint, then continue flying. Then Magnetic filed interference came up and the drone took off and reach 17M/S and hit a tree. It was not in sports mode and there was absolutely no control.
What was the surface you launched from?
 
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sar104

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#3
With nothing but one screenshot to go on it's difficult to answer your question. However, based on that screen shot I would guess that there was significant magnetic interference at the takeoff location, which could have been very local. At the point of the screenshot, 11 seconds into the flight, the FC has dropped out of P-GPS into ATTI mode because of the resulting discrepancy between the compass and IMU yaw values. That should have been good news if you had known how to fly it in ATTI mode, but either you didn't or it had already gained enough speed trying to hold position in P-GPS mode that it ended up colliding with the tree.

If you would like to post the flight log (txt) and even better, the mobile device DAT file, then it should be possible to pin down exactly what happened.
 
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job996

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#5
With nothing but one screenshot to go on it's difficult to answer your question. However, based on that screen shot I would guess that there was significant magnetic interference at the takeoff location, which could have been very local. At the point of the screenshot, 11 seconds into the flight, the FC has dropped out of P-GPS into ATTI mode because of the resulting discrepancy between the compass and IMU yaw values. That should have been good news if you had known how to fly it in ATTI mode, but either you didn't or it had already gained enough speed trying to hold position in P-GPS mode that it ended up colliding with the tree.

If you would like to post the flight log (txt) and even better, the mobile device DAT file, then it should be possible to pin down exactly what happened.
I would like to, but not sure how to download the flight log. When it took off, I had absolutely no stick control. I have three Phantoms before, which weren't as technical. Just saying I'm not new to drones.
 

sar104

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#6
I would like to, but not sure how to download the flight log. When it took off, I had absolutely no stick control. I have three Phantoms before, which weren't as technical. Just saying I'm not new to drones.
The lack of stick control will most likely have been while the FC was unsuccessfully trying to fly the aircraft in P-GPS mode. After it switched to ATTI you would have had full control. But there is no point speculating further without the log(s).

How to retrieve a V3.DAT from the tablet

DJI Flight Log Viewer - Phantom Help
 
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job996

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#7
Thank-you, ill8give it
The lack of stick control will most likely have been while the FC was unsuccessfully trying to fly the aircraft in P-GPS mode. After it switched to ATTI you would have had full control. But there is no point speculating further without the log(s).

How to retrieve a V3.DAT from the tablet

DJI Flight Log Viewer - Phantom Help[/QUOTE
Thank-you, I'll give it a go first thing in the morn
Thanks, I agree. Once you see the upload, the flight only lasted for what seemed like seconds, so there wasn't much time. I will try and upload first thing in the am. I'm on South American time atm.
The lack of stick control will most likely have been while the FC was unsuccessfully trying to fly the aircraft in P-GPS mode. After it switched to ATTI you would have had full control. But there is no point speculating further without the log(s).

How to retrieve a V3.DAT from the tablet

DJI Flight Log Viewer - Phantom Help
 

job996

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#8

sar104

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#9
OK - that's the correct flight txt log. The yaw data are very strange though, indicating that the aircraft started spinning when it entered ATTI mode at 10 s, and it's hard to determine what was happening. Can you retrieve and post the mobile device DAT file? That contains the actual magnetometer and rate gyro data.

Also, do you recall which direction the aircraft was facing at takeoff, and in which direction it flew off?
 

job996

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#10
OK - that's the correct flight txt log. The yaw data are very strange though, indicating that the aircraft started spinning when it entered ATTI mode at 10 s, and it's hard to determine what was happening. Can you retrieve and post the mobile device DAT file? That contains the actual magnetometer and rate gyro data.

Also, do you recall which direction the aircraft was facing at takeoff, and in which direction it flew off?
Not able to download the DAT file on Phantom help. The Drone was facing away from me when I took off.
Now I get a message from DJI saying that the Drone was purchased through Australian Amazon and delivered in the States, Australian warranty does not cover it! WTF! These things are sold Globally, why can they not warrant them globally?
 

BudWalker

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#11
Not able to download the DAT file on Phantom help. The Drone was facing away from me when I took off.
Now I get a message from DJI saying that the Drone was purchased through Australian Amazon and delivered in the States, Australian warranty does not cover it! WTF! These things are sold Globally, why can they not warrant them globally?
Upload the .DAT to a public sharing site like DropBox or GoogleDrive. Then post the link to that uploaded .DAT.

"Facing away from you" doesn't quite have enough info. Which direction was the Drone facing? North, East,... ?

But, from the .txt it appears that you were standing SW of the drone and it was facing you.
1537620776622.png
The yellow A is the AC and the green line is the recorded heading. The yellow T is the tablet location.

Also from the .txt is a compass error at a height of 0.3 meters. Most likely caused by a geomagnetically distorted launch site.
1537620991446.png
 

sar104

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#12
Upload the .DAT to a public sharing site like DropBox or GoogleDrive. Then post the link to that uploaded .DAT.

"Facing away from you" doesn't quite have enough info. Which direction was the Drone facing? North, East,... ?

But, from the .txt it appears that you were standing SW of the drone and it was facing you.
View attachment 47421
The yellow A is the AC and the green line is the recorded heading. The yellow T is the tablet location.

Also from the .txt is a compass error at a height of 0.3 meters. Most likely caused by a geomagnetically distorted launch site.
View attachment 47422
I agree. Transforming velocities north and east into velocities forwards and right using the recorded yaw shows that there was a significant yaw error immediately stick was applied:

2018-08-23_[17-32-02][1]_01.png

The oscillation after the switch to ATTI is problematic though - the yaw data suggest that the aircraft was spinning. The OP did not answer the question on whether that happened, but it would be an unusual response from the aircraft.
 
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BudWalker

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#13
I agree. Transforming velocities north and east into velocities forwards and right using the recorded yaw shows that there was a significant yaw error immediately stick was applied:

View attachment 47432

The oscillation after the switch to ATTI is problematic though - the yaw data suggest that the aircraft was spinning. The OP did not answer the question on whether that happened, but it would be an unusual response from the aircraft.
Also puzzling is the apparent ascent while full negative throttle.
1537625191178.png
 

redserv

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#17
hi guys I frequently use this forum to educate myself about drones and potential problems that can occur with them. I am the owner of a MPP and when i see stuff like this it scares the **** outta me. With all the flight preparations and checks can stuff like this be pilot error? I get the feeling that sometimes ***** happens. Its scary when even you experts pilots cant figure out what happened. As for you Job96 I wish you nothing but the best and hope you ca get your drone replaced.
 

BudWalker

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#18
hi guys I frequently use this forum to educate myself about drones and potential problems that can occur with them. I am the owner of a MPP and when i see stuff like this it scares the **** outta me. With all the flight preparations and checks can stuff like this be pilot error? I get the feeling that sometimes ***** happens. Its scary when even you experts pilots cant figure out what happened. As for you Job96 I wish you nothing but the best and hope you ca get your drone replaced.
It's at least likely, if not probable, that this incident was caused by a launching at a site that was geomagnetically distorted. The easiest, most effective way to avoid this is to confirm that the heading indicator on the map display is consistent with the AC's actual heading. If these don't agree then the AC should be moved to another location before launch.
triangle.jpg
 

sar104

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#19
hi guys I frequently use this forum to educate myself about drones and potential problems that can occur with them. I am the owner of a MPP and when i see stuff like this it scares the **** outta me. With all the flight preparations and checks can stuff like this be pilot error? I get the feeling that sometimes ***** happens. Its scary when even you experts pilots cant figure out what happened. As for you Job96 I wish you nothing but the best and hope you ca get your drone replaced.
The OP vanished without posting the DAT file, so the analysis was not complete. But to answer your question - yes - these events are often pilot error, at least to the extent that the pilot often didn't properly check that the takeoff location was not magnetically compromised.
 

redserv

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#20
The OP vanished without posting the DAT file, so the analysis was not complete. But to answer your question - yes - these events are often pilot error, at least to the extent that the pilot often didn't properly check that the takeoff location was not magnetically compromised.
Ok i Got you, so should the pilot have checked his compass and imu readout before take off? I feel bad for the guy and even freaked me out that this can happen to me, I am just trying to gather data as I am a new pilot. Thanks for taking the time to help me understand further.
 

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