Mavic Mini - Sudden Flyaway (A/C logs available)

[Henfri]

Hello,

my son just had a Mavic mini (1st Gen) Flyaway. He flew just fine for a while, but suddenly, the Mini flew east and descended. Before impact, it slowed down, but then it went down.

I was able to download the logfiles as Dat (there was no micro-sd in the drone). But I cannot convert is with datcon or csvview.

createDatFile invalid header - proceeding
Aircraft type unknown: Assuming 4 cellls per battery
Total Error Ratio 100,00%
Reverting to simple time axis processing becasue
not enough valid GPS data exists before the 1st rollover

Thus, I have uploaded the dat-file. I hope that is ok.

Can you help me on this?

Best regards,
Hendrik

 

[Yorkshire_Pud]

You could try uploading the normal .txt flight log, its name should be something like DJIFlightRecord_YYYY-MM-DD_[hh-mm-ss].txt.

 

[Henfri]

Hm, do I get that also via DJI Assistant?

 

[Meta4]

I was able to download the logfiles as Dat (there was no micro-sd in the drone). But I cannot convert is with datcon or csvview.

The file that matters isn't on the drone, it's on the phone or tablet that was used.
To get it ...
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.
Or .. just post the txt file here.

 

[Henfri]

Thanks.
The reason why I did not find logs on the Mobile is, that in the Pinned post in this forum, it points to DJI\dji.go.v5\FlightRecord. I found it in Android\data\dji.go.v5\files\FlightRecord.

I attach it.

Best regards,
Hendrik

 

[Yorkshire_Pud]

Thanks.
The reason why I did not find logs on the Mobile is, that in the Pinned post in this forum, it points to DJI\dji.go.v5\FlightRecord. I found it in Android\data\dji.go.v5\files\FlightRecord.

I attach it.

Best regards,
Hendrik

Yeah some people don't include the full folder sequence to the flightrecords folder.
Sorry I had assumed you had found the folder on the phone, I forgot that the DATs on the drone follow a similar naming scheme, my mistake.

Your log on Phantomhelp = DJI Flight Log Viewer - PhantomHelp.com

 

[Henfri]

Nö, no. Not your fault.
Your Link from the previous Post helped. I have attached the file to the previous Post already

 

[Meta4]

Thanks.
The reason why I did not find logs on the Mobile is, that in the Pinned post in this forum, it points to DJI\dji.go.v5\FlightRecord. I found it in Android\data\dji.go.v5\files\FlightRecord.

Almost the entire flight was done without good GPS.
There was no GPS location data until 0:57.9 when approximate data became available.
It wasn't until 1:01.2 that the GPS data was good enough for the flight controller to use and record a homepoint

Because of this, there is no speed or distance data until approximate data shows after 0:58.1.
The data indicates that after GPS became available, the drone started to acellerate to a high with no corresponding joystick input and flew a curved path.

This is typical of a yaw error which is caused by launching from an area where magnetic interference deflects the compass which is used to provide the initial directional reference for the gyro sensors.
The problem doesn't show itself until GPS is available and then there is a data conflict between the compass and GPS.

The problem was due to the launch spot, not a problem with the drone.

 

[Yorkshire_Pud]

Should, because of a yaw error, the drone accelerate to speeds above the flight mode's limitation or is there something else in play here too? The speed limit is supposed to be 4m/s ~ 9mph in what I assume is a renamed cine flight mode?
I have never looked at flight speeds vs flight speeds in magnetic interference problems before.

 

[Meta4]

Should, because of a yaw error, the drone accelerate to speeds above the flight mode's limitation or is there something else in play here too? The speed limit is supposed to be 4m/s ~ 9mph in what I assume is a renamed cine flight mode?

That's quite common in a yaw error incident.
The drone is trying to correct and hold position, but it keeps moving in the wrong direction.
Each "correction"puts it further off course and it corrects again and again, getting faster as it goes.

 

[Yorkshire_Pud]

Ok thanks

 

[redserv]

Thanks for analyzing the Logs meta. Just for my education in this matter. To help avoid an issue like this, shoud the issue have:

1. Locked home point
2. make sure there were no compass error before take off?

Thanks in advance

 

[Capt KO]

Thanks for analyzing the Logs meta. Just for my education in this matter. To help avoid an issue like this, shoud the issue have:

1. Locked home point
2. make sure there were no compass error before take off?

Thanks in advance

Yes and yes. If a compass calibration is requested, first move to another location and see if warning goes away. Doing a compass calibration in a area with interference will result in a similar scenario as the failed flight.

 

[Meta4]

To help avoid an issue like this, shoud the issue have:
1. Locked home point
2. make sure there were no compass error before take off?

Having recorded a homepoint and no compass error won't prevent a yaw error.
You would need to ensure that the drone is pointing the same direction as the drone icon on your screen map.
ie. Icon points east + Drone points east
If there is a difference like Icon points east + drone is pointing south ...
Power down and move the drone away from the cause of the issue and start again.

The most common cause of yaw errors is starting up on reinforced concrete surfaces.
Avoiding them is a good idea.

 

[redserv]

Having recorded a homepoint and no compass error won't prevent a yaw error.
You would need to ensure that the drone is pointing the same direction as the drone icon on your screen map.
ie. Icon points east + Drone points east
If there is a difference like Icon points east + drone is pointing south ...
Power down and move the drone away from the cause of the issue and start again.

The most common cause of yaw errors is starting up on reinforced concrete surfaces.
Avoiding them is a good idea.

Thank you for clearing that up, much appreciated