I am an experienced drone Pilot & hold an FAA commercial drone license.  Two years ago, after a difficult pitch, I convinced my new employer to invest in its first drone, the DJI Phantom IV Pro+, for use in it's operations.
This week, I was using the drone (in 'P' mode) to take aerial shots of real estate (buildings).  Ideal conditions, clear with no cloud cover, minimal wind.  After a battery low warning, I landed the drone and inserted a fresh battery.

I started the drone back up as usual.  However, when it got to only 15-20 feet height, it strangely gave me the audible "you have reached maximum altitude".  Really bazaar, having never occurred at this height.  I spent a few moments repeatedly trying to get it higher (by landing & re-launching), but continually got the audible.

Then, without any prompting, the drone (while at the 'maximum' height of 15-20 ft) suddenly shot off to my left at full speed, where about 2 blocks it crashed into a concrete building under construction.  I was awestruck and shocked, as I watched our expensive investment headed to a fatal crash out of my control.

I am sure my employer will place the blame on me.  It is also unlikely I will be able to convince them to re-invest in another drone.

I would think that DJI would want to know about this.  Does anyone know . . .

• Does DJI offer any type of forensics or assistance in documenting the cause (malfunction, hacking, etc.)?
• Will DJI work with me in seeking a remedy?
  

Thank you!

Post the flight log and somebody will tell you exactly what went wrong.

ALABAMA Posted at 9-11 15:35
Post the flight log and somebody will tell you exactly what went wrong.

Thank you, but I have never retrieved a flight log from the drone.  Can someone guide me how to do so in a format that allows me to post it?  Thank you again!

Interesting case.
It sounds like two separate issues, but flight data would be needed to confirm it.

However, when it got to only 15-20 feet height, it strangely gave me the audible "you have reached maximum altitude".  Really bazaar, having never occurred at this height.  I spent a few moments repeatedly trying to get it higher (by landing & re-launching), but continually got the audible.
This sounds  very much like you didn't have GPS but did have VPS.

P54 of the manual gives a clue:
   Height is restricted to 26 feet (8 meters) when the GPS signal is weak and Vision Positioning is activated.
   Height is restricted to 164 feet (50 meters) when the GPS signal is weak and Vision Positioning is inactivated.

Then, without any prompting, the drone (while at the 'maximum' height of 15-20 ft) suddenly shot off to my left at full speed, where about 2 blocks it crashed into a concrete building under construction.  I was awestruck and shocked, as I watched our expensive investment headed to a fatal crash out of my control.
Again, data is needed but sudden out of control movement of a drone is usually a yaw error caused by launching from a magnetically dirty location.
Can you describe the spot you powered up the drone?

Does DJI offer any type of forensics or assistance in documenting the cause (malfunction, hacking, etc.)?
DJI will do forensic analysis, free if the drone is in warranty.
Or you pay if the drone is >1 year old.
Or you can get faster and free analysis here to give you a good idea what DJI would find in the data.

I have never retrieved a flight log from the drone.  Can someone guide me how to do so in a format that allows me to post it?  
Go to http://www.phantomhelp.com/LogViewer/Upload/
It has instructions to find the .txt file from your controller screen, which you can upload to that site.
Upload it and it gives you a summary of the flight data.
Post a link to that summary.

Or just post the .txt file

Labroides Posted at 9-11 18:02
Interesting case.
It sounds like two separate issues, but flight data would be needed to confirm it.

Will do...thank you so much!

Moultrip Posted at 9-11 19:02
Will do...thank you so much!

Labroides, thank you again for your kind assistance.  I followed the instructions precisely for a Phantom IV Pro+.  It indicates that the file(s) can be found in the 'dji.pilot.pad' folder.  However, I discovered that there were a huge number of folders within the dji.pilot.pad folder, then numerous files contained within each.  There appeared to be a few docs in each folder with a file date of 9/8/2020 (the date of the crash).

I ended up downloading the entire 'dji.pilot.pad' folder (including all folders/files contained).  Can you narrow my focus to the individual folder or file(s) I should target that would contain the needed flight data?

Or I could attempt to upload or provide a link to the entire 'dji.pilot/pad' folder if that is possible.

Thank you again.

Moultrip Posted at 9-12 20:15
Labroides, thank you again for your kind assistance.  I followed the instructions precisely for a Phantom IV Pro+.  It indicates that the file(s) can be found in the 'dji.pilot.pad' folder.  However, I discovered that there were a huge number of folders within the dji.pilot.pad folder, then numerous files contained within each.  There appeared to be a few docs in each folder with a file date of 9/8/2020 (the date of the crash).

I ended up downloading the entire 'dji.pilot.pad' folder (including all folders/files contained).  Can you narrow my focus to the individual folder or file(s) I should target that would contain the needed flight data?

Can you narrow my focus to the individual folder or file(s) I should target that would contain the needed flight data?
Inside the pilot.pad folder, you need to look in the DJI\dji.pilot.pad\FlightRecord folder where you should find the flight records.
They should be .txt files and the latest one should be from your last flight.

Labroides,

Thank you for navigating me to the relevant files.  Below are links to the last two txt files from the FlightRecord folder.

I will appreciate any help deciphering the data to determine the nature, circumstances & cause of the crash.

Please let me know if there are additional steps I need to take.

09/08/2020  11:07 AM
https://www.phantomhelp.com/logViewer/XIS9TB0VSTMZS0LLDQ9D

09/08/2020  11:04 AM
https://www.phantomhelp.com/logViewer/SS8YPLGKN42ONB0B91P2


THANK YOU!

Moultrip Posted at 9-13 13:31
Labroides,

Thank you for navigating me to the relevant files.  Below are links to the last two txt files from the FlightRecord folder.

In the second flight record, you launched without any GPS satellites and as mentioned in post #4, this restricted your altitude to 26 feet.
The number of sats gradually increased after 15.7 seconds and at 0:26.9 you had enough to start to record location data and the drone was able to climb higher.
As the GPS health never increased beyond 1/5, the drone never recorded a home point.

From 0:27.7 the drone is recording slow flight but you are only climbing higher and gave no input with the right stick until 0:32.
The speed of the drone rapidly increased to beyond normal maximum speed without any right stick input.

This is characteristic of a yaw error incident which is caused by powering up/launching from somewhere with a magnetic influence that deflects the drone's compass at power up when the gyro is being initialised.
To explain what happens after that is complicated, but the short version is that the drone's directional information is false and as it detects that it is off course, it attempts to get back on course.
But with the false data, each correction, puts the drone further off course and it corrects more, etc which causes the rapid acceleration without joystick input.

The launch spot is likely to be the cause.
There will have been some steel close by that caused the compass deflection at power up.
Reinforced concrete surfaces are the most common cause of this.

Labroides Posted at 9-13 14:56
In the second flight record, you launched without any GPS satellites and as mentioned in post #4, this restricted your altitude to 26 feet.
The number of sats gradually increased after 15.7 seconds and at 0:26.9 you had enough to start to record location data and the drone was able to climb higher.
As the GPS health never increased beyond 1/5, the drone never recorded a home point.

Labroides,

Your interpretations are invaluable.  I cannot thank you enough.

At least this may help me not only defend myself (with my employer), but also attempt to make a case to replace it.

Thank you again SO much!

Spot on data interpretation.  Good lesson learned too.  Good luck with DJI, but looks like operator error.  

Hello there Moultrip. I am sorry to read and to know what happened to your DJI Phantom 4 Pro +. Since there was a crash that happened before and this unfortunate event happened kindly please contact our DJI support team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. We have a team that will do there best to check the said drone and will give out the best resolution for this issue. If the said drone is still under the warranty period and it is evaluated as a non-pilot error, the warranty service will be provided. Again I am sorry for the trouble and thank you for your understanding.