Hi,
I was flying my drone here in Bangladesh over a river when the battery started getting low. The wind wasn't too bad and it was roughly around sunset. I got a couple more shots and started flying back when the battery was getting low. It said I had 2-3 minutes left and were close to my home point (40m or so). As it was coming back (RTO) it said it was on really low and suddenly lost complete RC connection. I didn't get any signal or anything from the RC until I promptly restarted it. When I finally got a signal it said it was forcefully landing and the landing area was unsuitable with 10 seconds of battery remaining. I couldn't see where it had landed because the video signal was pixelated. Then the battery died. I believe it may have landed on the water.

I bought the drone and DJI care refresh and refresh+ in Western Australia at my local JB HI-FI. I was wondering if I could claim it here in Bangladesh as my trip doesn't end until a month or so. I want to claim it now so that DJI doesn't say that I waited too long to claim the service. Several different things happened during that flight so I'm sure I can claim it under Care Refresh. Signal Interference, Signal Loss, Wind Interference and Human error along with a supposed water landing and/or flyaway.


Please Help

I believe you are out of luck for several reasons.
1) the drone is in a different country,
2) unless the flight logs show there was a problem with the drone then this would seem to be pilot error, see * below.
3) claiming for damage under care refresh requires that you have the drone or perhaps significant bits of the drone in your possession.

If you have flyaway coverage then things may be somewhat different but I still suspect that the claim will have to be submitted to DJI Australia or what ever section of DJI covers Australia and will possibly be dealt with via your address in Australia.
*      With regards to flight logs, the drone records two flight logs on the screen device (phone) attached to the controller, they are a .txt flight log and a DAT flight log. If you have a look at the webpage https://www.phantomhelp.com/logviewer/upload/ and follow the instructions there you should be able to find the txt flight log for the flight. Assuming so, post that flight log here and someone will probably have a look at it for you. Alternatively upload a copy of the .txt flight log to that website and then post the link that is shown once the log is processed or do both.

If you do not sync your logs then in the folder where you found the txt flight logs there should be another folder, its name starts MCDATF....... in there you should find a .DAT file with a time stamp that aproximatley corresponds to the time stamp of the flight. If you can find  the .DAT you could post that here too.


Also if you have a look in the "profile" or "me" section on the front page of the App you will find two things,
1) a flight records section which will show you the flights recorded on your phone, if you open that section you can replay the flight on a map.
2) I think the "find my drone" trigger is somewhere in profile or me. If you trigger that it, from memory, shows you a map to where the drone last had a connection to the controller. If you get ther quickly there might be a slim chance that the drone still has enough power to beep and flash its LEDs.
If you try that obviously watch out for snakes and the like.

The Mavic Mini is VERY GOOD at hiding, I put mine into a bush and even though I was within arm's length of it I could not spot it, I ended up sticking my arm into the bush in various places until I could see part of me on the screen and then moved my hand towards the camera.

Hi, there. Sorry to hear about this. For this situation, you are advised to contact our team via support@dji.com to report your situation and open a case. We will try our best to help you out. Thank you.

DJI Thor Posted at 6-25 19:38
Hi, there. Sorry to hear about this. For this situation, you are advised to contact our team via  to report your situation and open a case. We will try our best to help you out. Thank you.

Will do,
Cheers

Sean-bumble-bee Posted at 6-25 08:23
I believe you are out of luck for several reasons.
1) the drone is in a different country,
2) unless the flight logs show there was a problem with the drone then this would seem to be pilot error, see * below.

Hey,
I just had a look at the logs and well I see why we didn't find it. It definitely landed on the water and must've gotten carried away by the tide. We went out to search for it after 5-10minutes or so as it was difficult finding a boat and it was getting dark.

Anyways here is the flight log:
https://www.phantomhelp.com/logviewer/26Y3638I4LUM5ST8QIH0/

Also, I don't believe it was my fault as I completely lost the downlink for whatever reason. That definitely wasn't meant to happen and I believe that is what cost me the drone. I definitely would've made it back (to land or possibly the home point) otherwise as sport mode should've definitely been fast enough.

Que lamentable, el drone tiene que alertar del nivel de batería me imagino que no prestaste atención, y si estabas en una zona de montanas, playas o lagos el viento agota la batería mucho mas rápido, lo digo por experiencia, lo ideal es acercarse al punto de aterrizaje con 20% de batería restante. Para que no sucedan estos accidentes. lo lamento mucho espero que puedas hacer algo para resolver este accidente.

TPGK Posted at 6-26 22:56
Will do,
Cheers

You are most welcome. Should you have any further inquiries, please feel free to contact us.

I am afraid I can't see anywhere in the log that really ties up with your recollection of the flight.

That I can see you may have taken three photos, between 16:49 and 16:56, at this point the drone was 960ft from the home point and the battery was at 16%. (See the PH spreadsheet column BK / 63, entitltled ''CAMERA.isPHOTO''.)
You then flew the drone away from the home point until around 17.58 when the drone was over 1900ft away from the home point and the battery was at 11%. (NOT GOOD)
At around 18:07 (battery at 10% and a height of 37 or so ft) there was a major disconnection lasting 1min 39sec. I do not know what ground clearnace you had at this point but during this disconnection the drone presumably started a failsafe RTH and somehow got to 1533ft from home.
When the connection was restored the battery was at initially reported to be still at 10%, I am pretty certain this is either an error or there is some form of delay in the drone transmitting the battery percentage or a delay, somewhere, in the calculationof the percentage. because 0.4seconds later the battery level reads 2%, which sounds more realistic to me. The drone's reported height is -15.7ft.
It seems you gave it full throttle to regain some height (sensble) but turned the drone at an angle, NOT perpendicular, to what may be a river bank and gave the drone forward stick. In so doing you moved the drone to 1586ft away from home and a few feet from what may have been safety.
The log ends at 20:17 with the drone 22ft below the takeoff point.

I think you made the lethal mistake just after taking those photos, you should have brought the drone home at that point. Instead you flew away  from the home point.
I think the ''nail in the coffin'' was the very end of the flight when connection was regained.  I am not sure if the 'bank' the drone was heading for (south?) was safe, dry land or just semi submerged plant life but if you had headed perpendicular to that 'bank', rather than at an angle to it, I suspect you could have got the drone over the vegetation/land. However if you had turned the drone perpendicular to the opposite bank (north?) and headed for that north? bank I do think you could have got the drone safe.




All the above said if you look at the log on Phantomhelp or better yet download the csv from there, open it with a spreadsheet program and sort that spreadsheet by column FI / 165,entitled ''App.Warning'' you will find a 19 direct warnings about propeller speed and 54 warnings about possible prop warpage. They are all part of the same thing, it looks as if one or more of your propellors was warped and generating reduced lift.

The props needed checking and probably replacing.

Sorry it's not a favouable analysis and maybe now that I have done it some one will check it and correct any errors, or perhaps you could post the log over on Mavic pilots.

Sean-bumble-bee Posted at 6-29 11:03
I am afraid I can't see anywhere in the log that really ties up with your recollection of the flight.

That I can see you may have taken three photos, between 16:49 and 16:56, at this point the drone was 960ft from the home point and the battery was at 16%. (See the PH spreadsheet column BK / 63, entitltled ''CAMERA.isPHOTO''.)

I can vividly remember coming back after taking the photos, not flying further away because I was aware that I was at 16% and a person next to me said to come back after taking those photos. I had done this many times before and was sure I could make it back so I'm not particularly sure what happened. Maybe I'm not remembering the situation to 100% accuracy (I'm only human) but I'm sure that I was in the process of coming back. I couldn't actually really see what/where I was turning to as the GPS map on the left and the compass wasn't showing any data until maybe a couple seconds after I regained connection.


With instinct I tried to get as high as I could while accelerating to what I thought was land/the home point. The connection loss happened when I was standing roughly a little bit lower than the original height that the drone took off from as I was standing on some stairs to get away from the trees that were causing signal interference. I ignored the warped prop issue as I had done the instructions required to correct + I changed the propellers afterwards (when I first got the issue). I also visually inspected the props and they looked the original shape. Now I'm not sure whether or not the "find my drone" satellite image was updated as when I went to go searching for it, on the map the drone was on land. When we went we were directly over the last known location and it was water.

The logs show that it was sinking shortly after landing so that makes sense. Also my sense of scale was very very disproportionate as the drone was roughly 450-500m away prior to the connection loss and not 50-60m as I thought. The main thing that cost me was the connection loss as in my opinion I've flown with low battery and tough weather but I still made it back every time. I understand that I risked the drone by flying with low battery like that but definitely could've made it back.   

TPGK Posted at 6-30 04:07
I can vividly remember coming back after taking the photos, not flying further away because I was aware that I was at 16% and a person next to me said to come back after taking those photos. I had done this many times before and was sure I could make it back so I'm not particularly sure what happened. Maybe I'm not remembering the situation to 100% accuracy (I'm only human) but I'm sure that I was in the process of coming back. I couldn't actually really see what/where I was turning to as the GPS map on the left and the compass wasn't showing any data until maybe a couple seconds after I regained connection.

Do you agree that the photos were taken around 16:50?
If so then sorry but the log indicates that you then flew the drone AWAY from the home point, NOT towards it.
Could your sense of direction have become lost or reversed? Afterall you did spin the drone through 360deg shortly before 16:50.

With regards to ''The main thing that cost me was the connection loss as in my opinion'', if you mean the disconnection at 18:07, it certainly did you no favours. BUT, and assuming the log is correct, just prior to that disconnection the drone was over 1930ft away from the home point with only 10 or 11 percent of the battery charge remaining.
Being generous the drone seems to have been moving between 188ft and 204ft per battery percent during the flight. However, even if, at 18:07, you had manually flown the drone straight towards the homepoint I think it is HIGHLY unlikely to impossible that the drone would have made it home.

Once you get to these sort of percentage-charges the drone's ability to make headway is progressively more and more curtailed so I am absolutley certain that you would not have been able to get anywhere near an average of 193ft per battery percent on the return trip. I would guess that beyond somewhere around 17:30 getting the drone back to the homepoint became at least questionable.
At 18:07 and beyond, your only hope of saving the drone was a remote landing on one of the river banks.

What do you mean by ''The logs show that it was sinking shortly after landing''?
What indicates ''landing'' to you?


I am NOT trying to belittle you, but the above is what the logs appear to say to me.

Hi,
I do agree that I did take the photos around then yes but shortly after I did turn around in my perspective. Maybe I lost sense of direction but I don't think so. Computer data is better than a humans memories so that may have been the case.

While I understand getting back to the home point would've been unlikely to impossible given the circumstances, I still should've been able to make it to some sort form of land even if it may not have been close to the home point. Yes it wouldn't be ideal as I'd have to recover it in a possible awkward location but I'd at least still have the drone. As for the river when I went to go find the drone, the vegetation shown on the satellite imagery was very different from the real life and there wasn't as much vegetation as thought.

By "sinking" I meant that the drone had descended from the original ground elevation (roughly 2-4m above the sea level) and so I'd assume that meant that the drone was sinking into the river.

As for landing I was referring to the emergency supposed water landing it did at critical battery level.

Also I understand that you aren't trying to belittle me lol. I'm simply just not sure what happened that day matches the logs but after further analysis I see that I may have screwed myself over.

TPGK Posted at 6-30 04:07
I can vividly remember coming back after taking the photos, not flying further away because I was aware that I was at 16% and a person next to me said to come back after taking those photos. I had done this many times before and was sure I could make it back so I'm not particularly sure what happened. Maybe I'm not remembering the situation to 100% accuracy (I'm only human) but I'm sure that I was in the process of coming back. I couldn't actually really see what/where I was turning to as the GPS map on the left and the compass wasn't showing any data until maybe a couple seconds after I regained connection.

The main thing that cost me was the connection loss as in my opinion I've flown with low battery and tough weather but I still made it back every time. I understand that I risked the drone by flying with low battery like that but definitely could've made it back.  

Your flight data tells a very different story.
You lost the drone because you have very little awareness of the state of the battery, or what you were doing.

Here's the story according to your flight data.
At 15:27 the drone was 90 metres from home and the battery was getting low (23%).
The drone was then flown further away from home, reaching 260 metres when the low battery warning came on at 20%.
Instead of coming back, you flew it further away and another low battery warning came on at 16:35.6 with the drone 320 metres out and battery at 18%.

You hovered hovered for a while and then flew even further away, at full speed in Sport Mode, reaching 590 metres at around 18 minutes when the battery hit 10% which is critical low voltage level.
Shortly after, downlink was lost and when it was regained 1:40 later, the drone was in RTH and 120 metres closer to home (now 470 metres).
You lost signal because the drone was very low above the river with trees blocking the signal.

Shortly after that the drone started to autoland as it's programmed to on reaching critical low voltage level.
Signal was lost at 20:17.1 when the drone autolanded in the river.

This flight shows some very poor piloting and a lack of awareness.
The drone was close to home and then flown well away even though the battery was low.
After receiving a low battery warning, it was flown even further away using (battery sapping) Sport Mode.
And when it started autolanding (which took 30 seconds), even though the drone was only 10 metres from the river bank, there was no attempt to fly towards the shore.

Hi TPGK,

Had a look at your log too.
Many many warnings, but you did not stop flying yiour Mini1.

At 23seconds in flight:"Propeller rotating too fast. Wind resistance affected. Return to home and land promptly. Check whether propeller on beeping ESC is warped or damaged.; Return to home and land promptly. If any of the propellers are warped"
A good reason to stop flying!

At 40seconds in flight: (and this warning many many times in flight)
"Return to home and land promptly. If any of the propellers are warped..."

At 1m56s in Flight:
"Propeller(s) rotating too fast"
Typical for MINI1 with problems with their blades, a very good reason to bring it home....


At the end of your flight (15% battery) full stick forward in Sport mode but flying away from HomePoint.
17m06 - 292 meters away (15%)
17m45 - 554 meters away (now 12%)

At 10% battery MINI1 into critical battery landing....

Warning summary in my chart.

But did you stop with inputs during the last critical landing?  all inputs afe possible, so mayby find land closeby....

cheers
JJB

JJB, do you happen to know how the drone will have behaved during the long disconnection that started at 18:07?
Since it moved 404ft towards home I assume it must have climbed to RTH height 98.6ft and then started to flight home. From an experiment with my (well charged) Mavic Mini I think the climb will have taken around 7 seconds.

Where I am stuck is whether or not the drone will have then flown horizontally until the forced land began after which would it stopped moving horizontally and started to descend vertically or would it have combined horizontal flight and, because of low battery charge, descent?

Also what would the descent rate be when outside of VPS range?

Any idea why there are some erratic and uncommanded yaws from around 17:25 to 18:07?

Sean-bumble-bee Posted at 6-30 15:39
Slup, do you happen to know how the drone will have behaved during the long disconnection that started at 18:07?
Since it moved 404ft towards home I assume it must have climbed to RTH height 98.6ft and then started to flight home. From an experiment with my (well charged) Mavic Mini I think the climb will have taken around 7 seconds.

Slup?

Correct about the disconnect behaviour...

At 18m6.7 - distance out 590 meter at 11 meter baro height - 10% batt
disconnect
At 19m46.3 - distance out 467 meters at minus -4.8 - 2% batt

So in beween: climb to RTH setting of 30 meter, flying towards HP, bc low batt autolanding from RTH setting height.
As it has moved from the position at 18m06 it has climbed and reached the RTH setting height before if has flown towards HP.

AFAIK autoland/critical land decends speed is 2 m/s for a MINI1.Landing is never combined with forward speed. (if drone can handle the wind, otherwise it will land + drift away)

I do not find any erratic yaw inputs between 17:25 and 18:07.

cheers
JJB

JJB* Posted at 6-30 23:49
Slup?

Correct about the disconnect behaviour...

Ahhhhh oooooooooops, a tired mistake sorry. Corrected.

Thanks for the info about the descent etc..
I am on a MacBook at the moment and it does not like CsvView for some reason so I can't process the csv to produce a chart but if you slowly drag the Phantomhelp scroll button between those times the log reports some yaw twitches without there being any corresponding stick input.
On my Windows machine those twitches were visible in the output of CsvView, I imagine they'd show up in FRAP.

Sean-bumble-bee Posted at 7-1 00:33
Ahhhhh oooooooooops, a tired mistake sorry. Corrected.

Thanks for the info about the descent etc..

just some user rc yaw input, drone responded.

white line in the 17m25s mark



cheers
JJB