Mini 4 Pro lost over water - DJI says pilot error - need second opinion

[Pavle Lucic]

I was flying my Mini 4 Pro near a lake when the screen suddenly went black.

I couldn't retrieve the drone. ( i was not sure was it in water or RTH was activated so i went to takeoff point to wait for drone )

I contacted DJI Support and they told me it was pilot fault. 

But looking at my video, I don't see the drone hitting water. 

The feed just cuts off while still flying.

I uploaded my flight logs to Airdata: https://app.airdata.com/share/TLurLt/GENERAL

Few things that seem suspicious to me:

• Signal dropped from 100% to 0% instantly (not gradual fade)
• My controller was still transmitting (uplink stayed 100%)
• All stick inputs reset to neutral at the exact same moment
• Battery was 39%, GPS had 31 satellites

Here is the video https://drive.google.com/file/d/16k1ic2VFnAf-f3rir4kSS-A9jVByw_q7/view?usp=sharing

Can someone take a look and tell me what you think?

Thanks

[Ken Jamrogowicz]

Early message says SD card is too slow for that aircraft. That could cause video to cut out. 

Also, evidently you are in some type of warning zone. Not sure what that is, but it could prevent RTH.

Ken

[B0 M0A0K]

I looked over your logs and the Airdata information.

As mentioned, you seem to get quite a few warning :

Low Risk: Satellite positioning signal weak. Low severity, impact on safety is likely not significant GPS signal weak. Hovering unstable. Fly with caution (Code: 30002).

Warning: Possible obstacle obstruction. Aircraft will temporarily pause flight to set direction (Code: 800379)
Warning: Possible obstacle obstruction. Aircraft will temporarily pause flight to set direction (Code: 800379)
Warning: Subject too far
Warning: Current RTH route close to GEO Zone(s). Pay attention to the aircraft's position on the map to avoid RTH failure
Warning: Possible obstacle obstruction. Aircraft will temporarily pause flight to set direction (Code: 800379)
Warning: Min flight altitude reached. Aircraft unable to continue descending

The SD Card warning is something I would have addressed immediately. The obstacle obstructions would worry me, do you know what it was doing when it generated these ? The minimum flight altitude is a red flag. I have only ever seen this when trying to land at a lower elevation than I took off (say walking on a hilly terrain)?

As mentioned, there is the GEO Zone warning. But that should not have stopped your drone from RTH so long as it didn't try to fly through the zone. I don't see the zone on the map, do you know where it was? I ask because DJI's GEO Zone's can be wrong. I have two locations near me where the drone reports a GEO zone on take off, but there is no such thing on local maps and certainly no no fly zones. It's just plain wrong. I have tried to tell DJI this but the tool for reporting it doesn't seem very reliable. 

What really bothers me is the report of DJI telling you that it was "Pilot Error". What is their evidence for this and what do they see from their logs that suggest you were in error? If they told me "Pilot Error" I would damn well want them to explain that.

It IS possible that you experienced a perfect storm of events, the SD card failed, the drone tried to RTH but came across the GEO Zone and just went into a hover. Something like that. But the SD card failing would not cause video transmission to fail immediately so you couldn't see what was going on on your screen. 

Sorry you lost the drone, it's happened to me so I know how bad that feels.