Mavic Crash, Can I please get a hand with Analysis?

[Simmo]

Hey Guys,
On our FB group in Australia, a guy has had a crash. He has DJI Refresh, but the AC fell into VERY Croc infested water, so no chance of recovery... DJI have said pilot error...I did my analysis of the logs and agree with DJI. However, even though it wont help the pilots cause to get a replacement for nothing.... I would like help to investigate the compasses...
The takeoff was from a boat, ontop of a fibreglass ice box. I'm thinking that even though he was flying in a satellite view comprimised area, that GPS health was actually affected by compass/imu conflicts??
Or, is it simply a matter of atti mode thumbs, and crash....
Have a look at the log at the end, when old mate gives full reverse, and full throttle, yet the pitch of the AC doesnt really reflect the input does it??
Anyway, over to you!!! DJI Flight Log Viewer - PhantomHelp.com

 

[sar104]

I'll take a look, but if you suspect compass issues then the mobile device DAT file would be useful - that has the actual compass data.

 

[Simmo]

Thanks buddy, I will ask him to do that. Have you got that instructional link handy on how to get it?

 

[sar104]

How to retrieve a V3.DAT from the tablet

 

[Former Member]

Hey Guys,
On our FB group in Australia, a guy has had a crash. He has DJI Refresh, but the AC fell into VERY Croc infested water, so no chance of recovery... DJI have said pilot error...I did my analysis of the logs and agree with DJI. However, even though it wont help the pilots cause to get a replacement for nothing.... I would like help to investigate the compasses...
The takeoff was from a boat, ontop of a fibreglass ice box. I'm thinking that even though he was flying in a satellite view comprimised area, that GPS health was actually affected by compass/imu conflicts??
Or, is it simply a matter of atti mode thumbs, and crash....
Have a look at the log at the end, when old mate gives full reverse, and full throttle, yet the pitch of the AC doesnt really reflect the input does it??
Anyway, over to you!!! DJI Flight Log Viewer - PhantomHelp.com

I feel bad for the pilot, but Im glad it wasnt you.

 

[Simmo]

Aww I'm feeling the Love there Rob, Thankyou so much!!!
Hey Sar104, he reckons that the file isnt there, I showed him the file structure to get to it and he is looking! I might hit the hay now, but wiil update y'all on the morrow!
Thanks for your assistance so far.

 

[sar104]

Aww I'm feeling the Love there Rob, Thankyou so much!!!
Hey Sar104, he reckons that the file isnt there, I showed him the file structure to get to it and he is looking! I might hit the hay now, but wiil update y'all on the morrow!
Thanks for your assistance so far.

It's there. It's always there. He just needs to look in the right place.

 

[sar104]

I don't see any aircraft problems in the txt log. GPS reception was poor close to the cliffs, but the aircraft response to elevator and aileron was appropriate throughout:









There was very little wind - it looks like he just flew it into the rocks. Since the aircraft was facing him, that may have simply been disorientation relative to the aircraft. Considering that it should have been clear that the aircraft was heading for the cliffs on the right (aircraft view), it's curious that he applied no left aileron and only very minor rudder inputs, which at the end were CW, i.e. in the wrong direction.

 

[Simmo]

Thanks mate, I've only just got in from work, he has not replied yet, but did indicate that he would look again this afternoon.

This is his flight recollection:
Was flying backwards and up and was watching both aircraft and the screen it looked clear of the cliff but saw rocks in the screen and didn't get time to stop befor it was to late befor flying back i checked by eye it was clear but in the vid it flew sideways i emailed dji again and they basically said unless i recover it i have no hope

This was my analysis:
Ahh well, in my amateur view it is a case of pilot error. A few bits and pieces in there we can learn from though I think. The high walls made it difficult for adequate satellite coverage, even though you had a few at times, your GPS Health was not good. Even though DatCon says there was no compass error, I'm not so sure. (However that would require more analysis from someone further up the food chain!) So if taking off in the boat caused a magnetic distortion, the two compasses and IMU would confuse the FC and cause the AC to be in Atti mode. It seems you flew quite well, the aircraft was responding well, and exactly as you inputted on the sticks. Position hold would have been compromised and braking etc would not have been like it 'normally is'. I think, too close to the cliffs, too slow to input the correct control, and crash. Sorry for your loss buddy, even if we get Sar104 to analyse the compass, DJI are still going to point the finder at you.

 

[Simmo]

Fellows, the OP has given up on looking for the file!!! And gone out and bought a new one to continue his travells around our Big Brown Land!
Thanks for your all your help @sar104 you are a legend as usual! (I'll buy ya a beer when ya come on over!!)

 

[Simmo]

@sar104
Sir, I have another one, what do you make of this???

Would love some advice when approaching DJI with my issue. Today while flying. My Mavic 2 suddenly disconnected from the controller and dropped into the ocean. Did not return home. Simply disconnected from controller. Have the footage that was being filled up and until the loss. Full battery, 2min flight up to failure. Fully updated. 372m distance 67m elevation.

 

[sar104]

@sar104
Sir, I have another one, what do you make of this???

Would love some advice when approaching DJI with my issue. Today while flying. My Mavic 2 suddenly disconnected from the controller and dropped into the ocean. Did not return home. Simply disconnected from controller. Have the footage that was being filled up and until the loss. Full battery, 2min flight up to failure. Fully updated. 372m distance 67m elevation.

Nothing obvious apart from some large pitch excursions due to the wind speed. Can you retrieve the mobile device DAT - I'd like a look at that.

 

[Simmo]

I have asked him to get that. Thanks mate.
Thats all I saw too was the large pitch angle. I havent got a paid account with AD but the free account said the wind at TO was 15mph, the operator flew into that headwind on the way out. The battery data etc was all good, I'm wondering high angle and battery falling out??
But no point summizing until we have the data to see.

 

[Simmo]

2019-05-12_16-39-47_FLY025.DAT

drive.google.com

 

[sar104]

2019-05-12_16-39-47_FLY025.DAT

drive.google.com

Nothing obvious in the DAT log data either, but the event stream ends with a couple of unusual entries that I suspect are precursors to the FC failing:

136.599 : {task_e}INFO:i2c3 core recovery||
136.599 : 7488 [L-BATTERY][ERROR] CMD_BUTTON_STATUS error||

I don't know what either of those really means, but I'm pretty sure they shouldn't be there.

 

[Simmo]

Thanks mate.
Can I ask what you think of the battery cell deviation eatlier in the flight.? Nothing to worry about?

 

[sar104]

Thanks mate.
Can I ask what you think of the battery cell deviation eatlier in the flight.? Nothing to worry about?

They don't look particularly unusual to me. Power delivery didn't seem to be the problem.

 

[Simmo]

Hi Guys,
@sar104 I see that Luke (the owner of the above logs) has posted another new thread, however I though that I would conclude this case in this thread.
@sar104 you've done it again my man!!!
DJI came back at luke with a standard script:

This is Dora from the data analysis team, and I will be assisting you on this case from now on for related inquiries about data analysis.

For your case CAS-XXX, we have finished the data analysis, and the result is as follows:

1. The aircraft was piloted under GPS mode after it took off and it responded to the pilot's control well. The home point: -26.8066101 153.1379296;
2. T=01:23, H=11.7m, D=373.4m, Battery 92%, the warning of High Wind Velocity popped up;
3. T=02:16, H=67.2m, D=374m, Battery 88%, the pilot pulled the pitch stick back, the aircraft flew backwards at 2.6m/s then the flight record ended and the last recorded coordinate: -26.8099343 153.1385000.

The record ended without any sign of abnormality, so we could not verify what happened afterwards.

We truly appreciate your support for DJI. If the aircraft couldn't be retrieved, we would like to offer you a 30% off coupon code for Mavic 2 Pro (without the remote controller and battery charger), which can be used on DJI's online store:

I then urged Luke to pursue with getting the DAT file looked at, as the initial analyst was definately looking at the TXT file only!
The reply cam back late today:


Thanks for your patience.

The unfortunate incident that occurred to your aircraft has been confirmed as a warranty case according to our second data analysis. If the aircraft couldn't be retrieved, we would like to offer you a 100% off coupon code for Mavic 2 Pro (without the remote controller and battery charger), which can be used on DJI’s online store:

So thanks Sar104 Buddy!!!
Recognising those few lines of code make this 2 out of 3 for replacements!!!