TLDR: Controller lost connection, drone didn't RTH, searched a wheat field for 3 hours.


Hi! I got my drone yesterday with the "Fly more"-kit. Charged everything up & did all the necessary updates and took it out flying for the first time.
-> Felt like a kid on new years eve

Sadly my Micro SD card did not work at all and it all the shops had already closed for the night. I plugged everything in before going to bed and went shopping for a card today. Plugged it in and it just worked. Sweet. I went out in the fields and started my flight. Managed to capture one photo and started to capture a video, when suddenly I lost the connection to the drone. 'Not too bad' I thought, 'it will RTH just like I configured in the settings'. Well .... it did not RTH. It did not reconnect either. Sadly I did not see it in that exact moment.
I went looking for it in the field, controller still trying to connect . Searched for an hour and did not find it (with 'Find my drone'). It did not return to home even after that hour, which I thought it might when the battery runs out.


I then went home, and searched the internet and found some reports of drones just dropping dead out of the sky (https://forum.dji.com/thread-289783-1-1.html).
I packed some things and went looking for it again for 2 more hours, but without any luck.

So here is all the data I have gathered:
App: 1.10.1

App Static Safety Data: 01.00.01.29
Aircraft Static Safety Data: ?
Aircraft Firmware: ?

Drone: DJI Mini 3 (Firmware ?)
Controller: RC-N1 (Firmware 04.16.0300)
Log Viewer: https://www.phantomhelp.com/LogViewer/12LH1PMM087Q0F6DL4V4/#
Last Speed: 25mph
Last height: 123 ft

My Position & RTH (+-10 meters):  https://goo.gl/maps/baXXPkaW95qCrxr78

Weather: Some clouds, no rain, 15-40  kmh winds NO (9-24mph) -> See here: https://www.wetter.com/deutschland/puchheim/DE0008430.html

Wheat field: About waist heigh, trying to find the needle in the hay stack, has bunnies and maybe mice

Before the last slight turn I switched to FPV-Mode. I do think it has to do something with that. I did not do that yesterday. I might be completely wrong. I will go and search again in the evening and open a support ticket with DJI.

Please help, any suggestion will be appreciated. Cheers!

EDIT: Added firmware &  application versions, I do have last cached video and can upload it somewhere if needed

Hi there, we are sorry to know about the accident. Hope you can retrieve the drone. If you're able to retrieve the drone, you can start a case through the link below and send the drone in for diagnosis and repair. If there is a doubt about the accident, data analysis can also be applied as long as the drone is within the warranty period. http://www.dji.com/support

Corrected ..... I think.

There was a wind blowing from the ENE to the WSW at 6.4m/s ( Airdata)
I would walk the RTH flight path from the drone's  location at 9:39, 579 seconds, and slightly either side of that track plus extend the search area slightly to the WSW of that track. The drone should have retraced the 50m before the disconnection and that would have taken it to 579sec at 48.15506057, 11.39222964 or thereabouts.


If the motors died on the way back the drone would have been blown WSW during the freefall. From the RTH height of 70m I think it would have take between 4 & 6 seconds to hit the ground so up to 38m off that track but, given the angles between the wind and the RTH flightpath (appprox E) {see the column entitled ''HOME.courseLockAngle'' in the csv of the log } I think that 38m WSW amounts to approx 10m perpendicular to the flight path.


My trigonomtery is very rusty so check those figures,

Sean-bumble-bee Posted at 6-3 08:32
Corrected ..... I think.

There was a wind blowing from the ENE to the WSW at 6.4m/s ( Airdata)

Wow! Thank you.
If I understood correctly: The area marked in yellow in that picture should approximately be my search area?

Is it common behaviour, that the drones retrace 50m "backwards"?

With regards to your box, no sorry that is incorrect. The box extend the whole way to the home point and some what WSW of the "50m before" point......I THINK
.

With regards to "retrace". Retrace behaviours varies from model to model as does the entire RTH behaviour and notably the failsafe/disconnection behaviour. You really need to read the drone's manual in connection with these behaviours, every different model I have flown has caught me out with their RTH behaviours.

Some models do not have a last xyz retrace at all.

Sean-bumble-bee Posted at 6-3 10:17
With regards to your box, no sorry that is incorrect. The box extend the whole way to the home point and some what WSW of the "50m before" point......I THINK
.[view_image]

Thanks for the clarification.
Unfortunately the sun is setting right now, so I've stopped my search for now. I will continue tomorrow but with the size of the area and the height of the wheat my hopes are shrinking every second.

I really should've kept within line of sight and RTFM the next time.

Flopsinger Posted at 6-3 10:48
Thanks for the clarification.
Unfortunately the sun is setting right now, so I've stopped my search for now. I will continue tomorrow but with the size of the area and the height of the wheat my hopes are shrinking every second.

I don't think RTFM would have helped prevent the loss of the drone in this instance but I could be wrong. As far I have looked you did nothing wrong, RTH height was higher than I would have set for this flight but the 'biggie' is that the Failsafe option was appropriately set to RTH.

Where RTFM would have helped is in understanding where to look.

That "find my drone" didn't find it makes me wonder if the battery was dislodged, either in flight or in a  crash. How long after the disconnection did you start to use "find my drone" and where were you at that time?
Hopefully the likes of JJB* will be along some time soon and have a look.

Sean-bumble-bee Posted at 6-3 11:15
I don't think RTFM would have helped prevent the loss of the drone in this instance but I could be wrong. As far I have looked you did nothing wrong, RTH height was higher than I would have set for this flight but the 'biggie' is that the Failsafe option was appropriately set to RTH.

Where RTFM would have helped is in understanding where to look.

"As far I have looked you did nothing wrong"
-> That was how I felt like afterwards. It's not like I crashed into a tree or something. It just went from happily flying around to "no connection" and completely refusing to to anything. The last thing I do remember doing is switching to FPV-Mode and slightly turning. Maybe the battery really did disconnect completely mid flight.


" Where RTFM would have helped is in understanding where to look."
-> Yep. I now have plenty of time to do that. I did watch the tutorial video from DJI though.



"How long after the disconnection did you start to use "find my drone" and where were you at that time?"
-> I probably waited about five minutes. It wasn't that far away and should've returned pretty quickly - as it did yesterday. I was pretty much at the Home-Location, maybe a couple meters to the south at the "Kapelle". That would be about 160m/520ft from the drones last recorded position.


I went to the location again just before the sun set completely and just scouted the area. Unfortunately the area to the left of the field is pretty dense forest and the bushes/weeds grew even higher than the wheat field.

With regards to the "find my drone" thing (FMD), in the circumstances of this flight it is best to search with FMD as quickly as possible.
The reasons being two fold but both rely on the drone still being powered.
1) you may move the controller back into contact which will or should update the drone's position. I am not sure what happens if the drone's GPS is broken i.e. whether or not the connection signal strength could be used to judge whether or not you were walking towards the drone or away from it.
2) if you do walk the controller back into connection you can trigger the fFMD lashing and beeping which can be a great aid to finding the drone.

Unfortunately if the battery gets exhausted or was disconnected or the Mini 3 Pro overheats and shuts down, which they are prone to do if powered on and not flying, then the last known location can not be updated nor can the flashing and beeping be triggered.

However, I can vouch for the fact that the flashing at least is a GREAT aid to finding the drone in darkness. I am deaf so beeping is useless to me. I put my mavic mini into a fir tree and couldn't see the actual drone but as this was a night flight the flashing LED  was like a light house and led me straight to the drone.

Flopsinger Posted at 6-3 11:54
"As far I have looked you did nothing wrong"
-> That was how I felt like afterwards. It's not like I crashed into a tree or something. It just went from happily flying around to "no connection" and completely refusing to to anything. The last thing I do remember doing is switching to FPV-Mode and slightly turning. Maybe the battery really did disconnect completely mid flight.

Hopefully, you will find your drone.  It is a sickening feeling when RTH does not work properly.  As added protection against loss I use the VIFLY Beacon - Wireless Buzzer.  It is well worth have the peace of mind in addition to the Find My Drone feature.

https://viflydrone.com/collectio ... beacon-drone-buzzer

DowntownRDB Posted at 6-4 05:15
Hopefully, you will find your drone.  It is a sickening feeling when RTH does not work properly.  As added protection against loss I use the VIFLY Beacon - Wireless Buzzer.  It is well worth have the peace of mind in addition to the Find My Drone feature.

https://viflydrone.com/collections/drone-buzzer/products/vifly-beacon-drone-buzzer

Unfortunately I did not find it today either. I'm quite exhausted and I just gave up.
I have contacted support today but have not gotten a reply yet. I'm still hopeful I won't have to bite the bullet and buy another drone.

This buzzer is a geat idea. I thought about maybe attaching an airtag or something like that but was concerned about the weight.This buzzer seems to be more suited to this kind of application.

Flopsinger Posted at 6-4 07:40
Unfortunately I did not find it today either. I'm quite exhausted and I just gave up.
I have contacted support today but have not gotten a reply yet. I'm still hopeful I won't have to bite the bullet and buy another drone.

Sorry you still haven't located your drone.  The VIFLY Beacon - Wireless Buzzer is well worth buying to protect any future drones that you get.  

Should have thought of this earlier but .... in the folder where you found the .txt flight log there should be another folder, "MCDATFlightrecords"  or something similar. If there are any .DAT flight records in that folder there may be a file whose date/time stamp predates the flight log's date/timestamp by several, or more, seconds and whose name contains "FLY0013" or "FLY013". If you can find the .DAT can you upload it to a file hosting website, make the page public and post the link here?
Alternatively, if you are on a Windows machine, download and install CsvView from
https://datfile.net/CsvView/downloads.html
and use CsvView to process that DAT.
If the processing succeeds you will see a list of things to look at, click "motor" or "motor speeds", I don't remember the name, and just look at the length, time wise, of the plot. Does it extend much beyond the end of the flight log.
Providing the controller and App are switched and connected to the drone, the DAT is recorded from drone switch-on/connection to drone-switch-off/disconnection. If the chart is, time wise,  just slightly longer than the flight log then it will not be much use but if it is noticeably longer than the flight log ( extends well beyond the end of the flight log)  then click "export" ( found at the left hand end of the CsvView top tool bar) and choose 'save the csv' or something similar then have a look in that csv for Lat and Long coordinate, if they exist what are the last set of coordinates?
I am on a Mac and CsvView does not run on this Mac so I can't check to see whether or not the DAT's csv has Lat and Long coordinates.
This is clutching at straws but there is nothing to lose by checking.
I doubt the DAT will be significantly longer than the flight log, the recording of both logs would be ended by a full blown disconnection, but its worth having a look..

Sean-bumble-bee Posted at 6-5 03:24
Should have thought of this earlier but .... in the folder where you found the .txt flight log there should be another folder, "MCDATFlightrecords"  or something similar. If there are any .DAT flight records in that folder there may be a file whose date/time stamp predates the flight log's date/timestamp by several, or more, seconds and whose name contains "FLY0013" or "FLY013". If you can find the .DAT can you upload it to a file hosting website, make the page public and post the link here?
Alternatively, if you are on a Windows machine, download and install CsvView from
https://datfile.net/CsvView/downloads.html

Unfortunately there are no .dat files in this folder. If I remember correctly this is due to having "Sync Flight Data" on?

Flopsinger Posted at 6-6 09:15
If I remember correctly this is due to having "Sync Flight Data" on?

Sadly that seems to be the case, I don't know why DJI decided to do that, nor why or when they decided to encrypted the DAT on the drone.
With the Phantom 3 the drone's DATs are readable and that's quite useful because it is recorded without fail even when the drone is disconnected from the controller.
Any luck finding your drone?

Sean-bumble-bee Posted at 6-6 10:01
Sadly that seems to be the case, I don't know why DJI decided to do that, nor why or when they decided to encrypted the DAT on the drone.
With the Phantom 3 the drone's DATs are readable and that's quite useful because it is recorded without fail even when the drone is disconnected from the controller.
Any luck finding your drone?

I did not find it.
Fortunately I just received an email from DJI support. They will replace the drone+battery completely free of charge as they could not prove any pilot error. Great customer service

I'm quite happy!

Flopsinger Posted at 6-7 05:18
I did not find it.
Fortunately I just received an email from DJI support. They will replace the drone+battery completely free of charge as they could not prove any pilot error. Great customer service

That's good.