Hi All,

I was flying my new Mavic 3 Pro in my backyard. I was hovering at about 4 meters recording my bamboo. I was slowly moving in cinematic mode. Suddenly the drone dropped straight out of the sky, hit my lawn and broke a gimbal arm.

I saw on my controller that there was some sort of disconnection. I should have taken a picture of the words I saw there. Anyway, I watched the footage of the video and the video stopped BEFORE the drone dropped to the ground. I didn't stop recording, so why wasn't there footage of the drone dropping?

It seems to me that there was a catastropic failure of some kind. The video stopped. The propellers stopped. The drone dropped to the ground and broke.  There were no obstacles nearby that the drone hit.

Here's the analysis from DJI.

1.    Unit was in TRIPOD mode with good GPS signal and was responsive to RC commands.
2.    At t= 374.1s, relative height=4.5m, the unit recorded an impact.
3.    Prior to impact, user commanded PITCH forward, ROLL right and YAW left.
4.    Unit was moving forward, while strafing right and rotating left as per user stick commands.
5.    Vision and Infrared Sensing Systems functionality is affected by surrounding environment, Vision Systems ability to detect and avoid obstacles are limited “e.g., tree branches, high-voltage lines, skewed rooftops, lampposts, reflective surfaces (such as water, snow, or surfaces without clear pattern and texture).”
6.    For more information, please refer to User Manual on “Vision System and Infrared Sensing System” and “Flight Environment Requirements.”
7.    Unit isn’t equipped with left / right obstacle avoidance.
8.    No sign of RC disconnection before impact.


So then I called and told them there was no impact at 4.5 meters (like they say in point #2), and they said that the impact was when it hit the ground. But that's not what point #2 says. It says that at a relative height of  4.5 , the unit recorded an impact. Wrong. There was no impact. I was in cinematic mode. Barely moving. You can see the footage of what I was doing right here.

https://youtu.be/GRe-T7qlJg8

There's drone footage at the beginning and at the end. As you can see, I was moving slowly. And then the video just stopped and it fell. I was moving the drone, yes, but only with small, slow movements, as you can see here. And there were no obstacles anywhere. And there's no footage of it falling to the ground.

And they are still telling me it's my fault. What a crock.

The simple way to check whether DJI's analysis is correct or not is to look at the recorded flight data to see what actually happened.

To post your flight data, go to: https://www.phantomhelp.com/LogViewer/Upload/
... where you'll find instructions to upload the data to that site and it will give a report
For help interpreting the data you can post a link for the report here.
Or just post the .txt file.

Labroides Posted at 7-6 13:48
The simple way to check whether DJI's analysis is correct or not is to look at the recorded flight data to see what actually happened.

To post your flight data, go to: https://www.phantomhelp.com/LogViewer/Upload/

Do I need the drone to post the flight data? The drone is at DJI.

ericamity Posted at 7-6 14:47
Do I need the drone to post the flight data? The drone is at DJI.

The flight data is on the phone or tablet you used for the flight.

Hi. I apologize for any inconvenience this has caused you. I was able to find your case number using your Forum account. I'll forward this information to our relevant team for further assistance. Rest assured that this will be taken care of and handled accordingly. Please keep an eye on your email for further updates. Thank you.

Labroides Posted at 7-6 15:03
The flight data is on the phone or tablet you used for the flight.

I didn't use a phone or a tablet. I used the RC.

ericamity Posted at 7-6 21:58
I didn't use a phone or a tablet. I used the RC.

The RC is a tablet with a controller attached.
Do you still have the RC?
Your data is recorded inside that.
You'll find it at:
Android\data\dji.go.v5\files\FlightRecord

Labroides Posted at 7-6 15:03
The flight data is on the phone or tablet you used for the flight.

I figured out how to find the flight logs but the .txt files are all in Chinese.

ericamity Posted at 7-6 22:38
I figured out how to find the flight logs but the .txt files are all in Chinese.

Upload the latest one to Google Drive or similar and post a link here and I'll show you what it says.

ericamity Posted at 7-6 22:38
I figured out how to find the flight logs but the .txt files are all in Chinese.

if you found a file named 'DJIFlightRecord_YYYY-MM-DD_[hh-mm-ss].txt', up load it to
https://www.phantomhelp.com/logviewer/upload/
then paste the resulting link here.
Labroides pointed you to this in post #2

Labroides Posted at 7-6 23:06
Upload the latest one to Google Drive or similar and post a link here and I'll show you what it says.

Funny. I can't seem to find the correct flight log. I have some from the 25th. But they don't seem right. Not the right time of day and not the right amount of time in the air. Maybe they're on the remote and not on my phone.

ericamity Posted at 7-6 23:29
Funny. I can't seem to find the correct flight log. I have some from the 25th. But they don't seem right. Not the right time of day and not the right amount of time in the air. Maybe they're on the remote and not on my phone.

If you haven't flown since the incident, the relevant file will be the latest one on the device you used for that flight.

Labroides Posted at 7-6 23:40
If you haven't flown since the incident, the relevant file will be the latest one on the device you used for that flight.

I'm so confused.
The uploaded file says 26 minutes but that same file says 2 minutes on my RC.

Here it is:

https://www.phantomhelp.com/LogViewer/6KWZK04TIIQXJQPK4FDC/

But that isn't the right flight. The flight for the crash was only a few minutes long. Can't figure it out.

ericamity Posted at 7-6 23:49
I'm so confused. On my RC, the last flights are on 6/25. There are three of them.  The last flight was me testing it (after the crash) so it should be the flight before that one. On my RC, it shows that flight to be 2 minutes.

But on my phone, it also shows three flights on 6/25. But the second to last one is over 26 minutes according to the uploaded log. That isn't right.

You could try uploading all the .txt files for that day to Google Drive or similar and posting a link?

Labroides Posted at 7-6 23:52
You could try uploading all the .txt files for that day to Google Drive or similar and posting a link?

https://www.phantomhelp.com/LogViewer/5H2SH7XFFPJJFWH61M6Y/

https://www.phantomhelp.com/LogViewer/0ZPIYTNDXC9HXJ84I8WW

https://www.phantomhelp.com/LogViewer/8SATREZAQWKEQ4J0BT8S

ericamity Posted at 7-6 23:57
https://www.phantomhelp.com/LogViewer/5H2SH7XFFPJJFWH61M6Y/

https://www.phantomhelp.com/LogViewer/0ZPIYTNDXC9HXJ84I8WW

Only the 2nd one was on the 25th.
It's the only one at a house, but appears to have landed safely.

Labroides Posted at 7-7 00:07
Only the 2nd one was on the 25th.
It's the only one at a house, but appears to have landed safely.

Those were the ONLY three logs on my phone. My RC has more logs, but those are the latest three logs.  

ericamity Posted at 7-7 00:14
Those were the ONLY three logs on my phone. My RC has more logs, but those are the latest three logs.  
[view_image]

Open the MCDATFlightrecords folder and see if there are any logs at all? If so upload ANY from June 25 to a file hosting site, make their page public and post a link here.
Those logs are .DAT logs and of some use  but perhaps not as much use as the .txt flightlogs.

Do that on both the controller and your phone.

How did the logs get to be on the phone?

If you have sync'd your logs then the DAT's may have been deleted but, after you have uploaded any DAT's that you find, you could, on the phone, try another sync and see if that downloads any missing .txt flight logs.

ericamity Posted at 7-7 00:14
Those were the ONLY three logs on my phone. My RC has more logs, but those are the latest three logs.  
[view_image]

Now I see all the flight logs on my phone (31 flights). But when I use iTunes to sync them over to my PC, only the three logs posted in the previous post show up on my computer. The others will not sync on iTunes. This really shouldn't be this difficult.

On another note, DJI has agreed to fix the problem, now saying that it HAS been determined to be a warranty issue.

But I want to see the correct flight log. Where is it? How can I access it?

I want to know:

1) why did the video stop recording before it dropped?
2) why did it lose power and drop?

Having this same drone back worries me. I want to record my daughter wakeboarding / tubing, etc., but now I have no confidence that something like this won't happen again!

Sean-bumble-bee Posted at 7-7 01:27
Open the MCDATFlightrecords folder and see if there are any logs at all? If so upload ANY from June 25 to a file hosting site, make their page public and post a link here.
Those logs are .DAT logs and of some use  but perhaps not as much use as the .txt flightlogs.

MCDATFlightrecords is empty.

I'm not sure how I got the logs onto my phone. I set the settings to automatically sync so I'm guessing that's how. But I simply cannot get the logs to my computer. Only three seem to want to transfer over (the three I posted before). The other 28 flight records won't transfer. Maybe I can upload them to phantomhelp directly from my phone?

Labroides Posted at 7-7 00:07
Only the 2nd one was on the 25th.
It's the only one at a house, but appears to have landed safely.

OK. I found the flight log. Here it is.

https://www.phantomhelp.com/LogViewer/3AQI9VOX8D918K8OTAXF/

DJI said there was no sign of RC disconnect before impact. I don't see ANY impact. But I do see RC disconnect right before the end of the flight.

And where does DJI get the info about my controller inputs? E.g., pitch forward, etc. ???

It looks like from this log that DJI flat-out lied to me when they said there was an impact recorded at 4.5 meters. Wouldn't that be on this log? And it looks like they lied when they said there was no RC disconnect before impact.

They ARE fixing the drone for free now. However, what happened here? And why didn't the drone return to home like it should have when it lost RC connection?

ericamity Posted at 7-7 13:21
OK. I found the flight log. Here it is.

https://www.phantomhelp.com/LogViewer/3AQI9VOX8D918K8OTAXF/

I cannot comment much on DJI's analysis, because they have said they saw evidence of an impact at 6:14.1.
Your recorded flight data ends 1:17 before that.
As DJI had your drone, they have access to the drone's data recording which continues even if the app is not connected.
With that data they can see what happened in the last 1:17.

The only questions I have are:
Is this data definitely from the right flight?

Is DJI's analysis the data from your flight or one from someone else?
How long after connection was lost did the drone continue to fly before things went bad?

DJI said there was no sign of RC disconnect before impact.
That's the only problem I can comment on in their analysis as the data from the app shows a loss of signal at 4:54.1.

I don't see ANY impact. But I do see RC disconnect right before the end of the flight.
With only data before loss of signal, you won't see anything that happened after loss of signal

And where does DJI get the info about my controller inputs? E.g., pitch forward, etc. ???
That's all recorded in the flight data.
What you've seen in the Phantomhelp report is a brief summary.
There's a lot more information in the actual data.
I can see your joystick inputs for each 1/10th of a second (and much more) for the data you posted.

It looks like from this log that DJI flat-out lied to me when they said there was an impact recorded at 4.5 meters. Wouldn't that be on this log?
No ... this log only shows what happened up until 4:57.1
If you flew for another 1:17 after losing suignal, their analysis could be correct.

And it looks like they lied when they said there was no RC disconnect before impact.
That's the only problem I can see, but I'm not sure whether it's importan or just a small mistake.

They ARE fixing the drone for free now.
That's a good result

However, what happened here? And why didn't the drone return to home like it should have when it lost RC connection?
If you were able to fly for 1:17 after the app stopped recording, that indicates that signal was not actually lost.

So the important question is:
How long did you fly after "losing signal"?

You won't get the same drone back from DJI.  They do not do things like that.  You will be getting a working one.

ericamity Posted at 7-7 12:34
Now I see all the flight logs on my phone (31 flights). But when I use iTunes to sync them over to my PC, only the three logs posted in the previous post show up on my computer. The others will not sync on iTunes. This really shouldn't be this difficult.

On another note, DJI has agreed to fix the problem, now saying that it HAS been determined to be a warranty issue.

Three logs are recorded by the equipment.
1) a .DAT which is recorded within the drone itself.
2) & 3) are recorded on the screen device used in conjuction with the drone. They are a) the .txt logs you have been handling and b) a second smaller .DAT. Both of these ( .txt and the second .DAT) can only be recorded whilst the screen device is in contact with the drone.

The .txt flight log is recorded from motor start to motor stop. BOTH DAT's nominally run from drone switch-on to drone switch-off and the drone's DAT does so. The screen device DAT and .txt are recorded only when the screen device is connected to the drone. The DAT on the screen device is also encrypted and DJI have the key.
If you sync your logs the process erases the screen device DAT's.
If you download and open the csv from phantomhelp you will find it contains an awful lot of information, the DATs contain more information concerning other data chanels although there is some overlap with the .txt. Attached is an editied version of the csv from your crash flight and the last line is quite important.
Note that OSD.isMotorOn switches to FALSE in the last line of the flight log.

It means the drone switched the motors off with the drone in the air !
I am also wondering how it managed to roll seemingly inverted 'instantly' and change its heading by 24deg also seemingly instantly?

With regards to the logs, copy them straight of the smart controller.

Have a look at post #7 in

https://forum.dji.com/forum.php?mod=viewthread&tid=287726

it might point you in the correct direction.

Sean-bumble-bee Posted at 7-7 17:33
Three logs are recorded by the equipment.
1) a .DAT which is recorded within the drone itself.
2) & 3) are recorded on the screen device used in conjuction with the drone. They are a) the .txt logs you have been handling and b) a second smaller .DAT. Both of these ( .txt and the second .DAT) can only be recorded whilst the screen device is in contact with the drone.

Hi Sean,

PH does not always show the correct data in the last converted record.....

So IMO "FALSE" for the column OSD.isMotorON is incorrect this log, see the other columns for the last record:

OSD.flytime = 0m 0.0s   [ last record CUSTOM.updateTime [local] time = previous record CUSTOM.updateTime [local] time ]
OSD.vpsHeight  = empty
OSD.hSpeed = empty
OSD.xSpeed = empty
OSD.gpsNum = 11   all records before 24
OSD.flycState - different mode than all before
etc
Make data analysis difficult if you cannot trust data....

Last recors minus1 :  "Aircraft not connected to RC", so last record drone data cannot be written in the log....
cheers
JJB

JJB* Posted at 7-8 01:52
Hi Sean,

PH does not always show the correct data in the last converted record.....

I don't understand all this, but I will say that I believe Sean is 100% correct. The drone simply stopped working and dropped to the ground. I watched it with my own eyes. My controller gave some sort of disconnect error (which I wish I had taken a picture of).

Anyway, I'm still talking to DJI about this. I have seen no indication of an impact at 4.5 meters anywhere. I do not know where they got this information.

Also, just as an update, DJI has repaired for free and is sending my drone back. However, it is a different drone. I have asked them if it's the same drone and was told it is not the same drone, so it has a different serial #. I asked it it's a new drone, and was told, "It's as good as new." So I have no idea if I'm getting a used drone back that's been repaired or what.

I am also expecting a call back from DJI next week. They are going to answer the following questions for me:

1) where is the data that shows an impact at 4.5 meters?
2) what actually happened to MY drone? What made it stop working?
3) what is the history of the drone they are sending back to me?

Maybe none of this matters anymore. IDK. I just have lost faith in DJI as the initial email they sent me seems way off base. Wrong data. And they weren't going to cover the repair. I'd have had to pay if I didn't dig into this myself.

Sean-bumble-bee Posted at 7-7 17:33
Three logs are recorded by the equipment.
1) a .DAT which is recorded within the drone itself.
2) & 3) are recorded on the screen device used in conjuction with the drone. They are a) the .txt logs you have been handling and b) a second smaller .DAT. Both of these ( .txt and the second .DAT) can only be recorded whilst the screen device is in contact with the drone.

What you are saying here matches what I saw with my own eyes. I saw it lose power and fall.

TonyPHX Posted at 7-7 15:40
You won't get the same drone back from DJI.  They do not do things like that.  You will be getting a working one.

Verified. I talked to a supervisor today and they are sending me a different drone. New drone? Used? Repaired? I have no idea and the lady I was talking to was unable to tell me. She said, "As good as new."

Labroides Posted at 7-7 15:29
I cannot comment much on DJI's analysis, because they have said they saw evidence of an impact at 6:14.1.
Your recorded flight data ends 1:17 before that.
As DJI had your drone, they have access to the drone's data recording which continues even if the app is not connected.

It looks like from this log that DJI flat-out lied to me when they said there was an impact recorded at 4.5 meters. Wouldn't that be on this log?
No ... this log only shows what happened up until 4:57.1
If you flew for another 1:17 after losing suignal, their analysis could be correct.

---

I did not fly anymore. It hit the ground and that was it. I tried taking off again a few minutes later, and flew for like 30 seconds, but could see that the gimbal was messed up so I landed.

"I don't understand all this, ................ I have seen no indication of an impact at 4.5 meters anywhere. I do not know where they got this information. "
Explanation.
DJI have access to logs that you do not, i.e. the DATs on the drone. DATs are recorded, in memory chips in the drone, from drone-switch-on to drone-switch-off and since the drone does not need to transmit the data to itself it should alwayes record a DAT from switch-on to switch-off. Any "impact" would probably have been recorded in that DAT. Labroides explained this in post #22 "As DJI had your drone, they have access to the drone's data recording which continues even if the app is not connected.
With that data they can see what happened in the last 1:17."

You did 'fly' again, at least twice, or at least start the motors, otherwise these two logs would not exist, 2023-06-25_[13-55-24] and 2023-06-25_[19-15-08].

In addition, as seen in the DAT's on the screen device (if you had them), the number in the name of the DAT increments by one each time the drone is switched on.
The DAT number is recorded in the .txt flight log, it is also shown in the csv of the .txt flight log, both in its own column, "HOME.dataRecorderFileIndex" and in a message in the column " APP.message"  e.g. Data Recorder File Index is 50.
Your crash flight had the DAT number 37, 2023-06-25_[13-55-24] had the DAT number 39 and 2023-06-25_[19-15-08] had the DAT number 42, which means you also switched the drone on at least 5 times after the crash flight.

ericamity Posted at 7-8 09:19
I don't understand all this, but I will say that I believe Sean is 100% correct. The drone simply stopped working and dropped to the ground. I watched it with my own eyes. My controller gave some sort of disconnect error (which I wish I had taken a picture of).

Anyway, I'm still talking to DJI about this. I have seen no indication of an impact at 4.5 meters anywhere. I do not know where they got this information.

Just to clarify matters, did you see, with your own eyes, the drone fall in a completely uncontrolled manner to the ground and did you notice if the motors had stopped rotating whilst the drone was in the air?
By fall I do not mean descend quickly, rather, I mean freefall under gravity in just the same way as Newton's apple fell.

I did start the drone again, yes. Twice that I remember. But there is only one flight that matters to me at this point ... the one with the crash.

Sean-bumble-bee Posted at 7-8 10:42
Just to clarify matters, did you see, with your own eyes, the drone fall in a completely uncontrolled manner to the ground and did you notice if the motors had stopped rotating whilst the drone was in the air?
By fall I do not mean descend quickly, rathe,r I mean freefall under gravity in just the same way as Newton's apple fell.

Exactly like Newton's Apple. From the way it fell, I do not believe the propellers were turning at all. It plummeted straight to the ground. And yes, I watched it with my own eyes, about 20 feet in front of me. It was like slow motion.

ericamity Posted at 7-8 09:26
It looks like from this log that DJI flat-out lied to me when they said there was an impact recorded at 4.5 meters. Wouldn't that be on this log?
No ... this log only shows what happened up until 4:57.1
If you flew for another 1:17 after losing suignal, their analysis could be correct.

I can't be certain what happened from your reply.
But the short version is that if your drone was only in the air for 4:57, DJI have given you analysis for a different flight, possibly not yours.
But if your drone was in the air for another 1:17 after 4:57, I'd trust their analysis.

But as you are getting a replacement from them, none of that matters much.

I would stop worrying about the quality of the replacement drone.  I buy a lot of drones and crash them plenty....the replacements are always very well handled.  You are working yourself up for no reason.

TonyPHX Posted at 7-8 23:14
I would stop worrying about the quality of the replacement drone.  I buy a lot of drones and crash them plenty....the replacements are always very well handled.  You are working yourself up for no reason.

Thanks! OK.

ericamity Posted at 7-9 07:25
Thanks! OK.

You get a refurbished drone back from DJI. Some claim that it is better than new as it has been thoroughly tested before being sent to you.
You wont be able to tell that it is not a brand new drone.

One thing you will need to check is if you have the DJI care plan on your drone is to make sure that you get the serial number of the replacement lodged in the care plan.