Happy New Year my Fellow Mavic Pilots,
I bought my Mavic Mini last December (2019), last Saturday I took it out for flight and lost it. At the distance of less then 500 mtrs and at the height of less then 200 mtrs, it started with lost of signlal (not obstacle between me/the controller and the drone). Auto RTH kicks in and FPV recovered, the problem is instead of flying back to home point the mini is flying further away in RTH mode. I cancelled the auto RTH and activated the RTH again manually, that didn't seem to change anything....still flying away further. The thing I noticed is that when it started going crazy the mini was flying sideways (yaw of the FPV) few seconds later its good bye 1 month old Mavic Mini. I went to the last known location of the crash, using the DJI Fly app map (find my drone), the point of the crash shifted from one point to another kilometers away. I've decided to use google maps instead, arrived at the site and lost hope as the coordinates given is a resindential area. My guess is someone found it on thier backyard and kept it or crashed on someone's double storey house. I've contacted DJI Support about the flyaway and RTH failure case, I've proviede the flight logs and all necessary information required. If this indeed a techncial failure/GPS faulty and not a pilot error, will I be compensated with a replacement drone ? anyone experienced similar problem and got a replacement drone before ?

I've proviede the flight logs and all necessary information required. If this indeed a techncial failure/GPS faulty and not a pilot error, will I be compensated with a replacement drone ?

If it can be shown that the cause of the incident was a DJI issue, it should be a warranty case.
Post your flight data here and you'll get quicker and better details of what the cause was.

Labroides Posted at 1-5 19:23
I've proviede the flight logs and all necessary information required. If this indeed a techncial failure/GPS faulty and not a pilot error, will I be compensated with a replacement drone ?

If it can be shown that the cause of the incident was a DJI issue, it should be a warranty case.

Hi Labroides, copy and paste the entire flight log text here in the thread ?

Dzulkernian747 Posted at 1-5 19:29
Hi Labroides, copy and paste the entire flight log text here in the thread ?

All I need is the .txt file which will have a file name like DJIFlightRecord_2019-06-11_[20-37-22].txt
Attach it or a dropbox link etc.

Labroides Posted at 1-5 20:15
All I need is the .txt file which will have a flie name like DJIFlightRecord_2019-06-11_[20-37-22].txt
Attach it or a dropbox link etc.

Right, here the link : https://drive.google.com/file/d/1AoVtARZdh_6klK2nd88UyJz06ao_BVBS/view?usp=sharing

Dzulkernian747 Posted at 1-5 21:42
Right, here the link : https://drive.google.com/file/d/1AoVtARZdh_6klK2nd88UyJz06ao_BVBS/view?usp=sharing

Your flight data looks like this: https://www.phantomhelp.com/LogViewer/2MSDZF0ZXXL3Y4KQJU8H/

You spent a lot of time around 600 feet altitude and the wind there was in the range that the drone could handle.
It was able to maintain horizontal position there.
But as you climbed past 800ft at around 9:47, we start to see the drone isn't holding position any more.
AT 800ft, it is drifting at about 1-1.5 mph
At 880 ft it's up to 4 mph
At 10:34 you gave it full stick in Sport Mode but could only reach 16mph in a NW direction.
But the max speed in Sport Mode (in still air) is 29 mph.
That's a good clue that the wind is going to be a problem if you need to push against it.

Interestingly your drone isn't pitching more than 20 degrees although the specs for the Mini suggest it will tilt to 30 degrees in Sport Mode.

It looks like loss of signal after 11:02 triggered RTH.
You leave RTH to run hands-off.
The drone correctly points toward the home point (SE) but gets blown to the south at about 8 mph.
The drone isn't trying hard to push against the wind, it's only tilting 8-10 degrees.
At 13:03.6 you finally try to bring the drone down lower but only get it down 100ft to 774 ft and you make a little headway toward the north.
You bring it a little lower but have trouble pointing toward home and the drone wanders.
The battery is fast running out and you go back to RTH mode at 14:4.6.
You leave it hands-off at 735 ft altitude being slowly blown to the SW.

At 17:03, low battery level forces autolanding to commence.
As the drone descends below 650 feet the drifting stops because it can hold position against the lower wind at that level.
The drone reaches the ground at 3.22790        113.07215.

The things that contributed to the loss of the drone were:
1.  You put it up too high and left it there.
If you had brought it down where it could have fought against the wind, it should have been easy to bring it home
2.  You wandered around the sky instead of flying toward home
3.  The Mini seems to be feeble and doesn't pitch as much as the specs suggest.
This means it's not going as fast as it should.

The place to look for the drone is 3.22790   113.07215

Excellent help. I have looked at several of these and generally it is the wind that is the issue

Also use the find my drone in the Fly App it works very well

I'll now have to learn how to read flight logs as well as how to export them!!

Gents, thank you for the data analysis. I have flow the drone in a much higher wind conditions (literally by the sea side) at higher altitude and still the drone is able to come home safely automatically. The day I lost the mini the wind was not as harsh, I am pretty confident the drone could have flown home through the calm breeze easily instead of fly further away once it looses the signal. I get strong wind warning a lot on the mini even when there is hardly any breeze. I guess just have to wait for DJI's official reply on this case......

"Interestingly your drone isn't pitching more than 20 degrees although the specs for the Mini suggest it will tilt to 30 degrees in Sport Mode" - does this applies when the RTH is turned on ?

Hello and good day adrianM. I am sorry to read and to know that you have lost your DJI Mavic Mini. Since this unfortunate issue happened. Kindly please contact out DJI Support Team for further assistance at https://www.dji.com/support?site=brandsite&from=nav. We would do their best to find out the reason of the incident and then the corresponding resolution would be provided. Again I am sorry for your loss and thank you for your understanding.

Dzulkernian747 Posted at 1-6 00:33
"Interestingly your drone isn't pitching more than 20 degrees although the specs for the Mini suggest it will tilt to 30 degrees in Sport Mode" - does this applies when the RTH is turned on ?

No, in RTH it does not pitch down to 30 degrees, its as in P-GPS mode.

In RTH mode and pushing the stick fully fwd will increase speed (thus more pitch down)

cheers
JJB

What was your return to home height set to

I'm just gonna state, I'm no fan of the RTH system. In fact I came here to post about it being an issue.  If you experience any warning for wind or otherwise it seems that the drone loses its RTH ability. The only option that remains is Land. More flights than not I've had no RTH ability even manually. You would think that by using update my home point... Which is another problem area.. that you'd then be able to initiate a RTH. It does not change anything. I've already decided that if you lose signal. It's not coming back.  Maybe someone can come clear up the issues with RTH because I've had this thing out about 3 times and am ready to write it off.

JJB* Posted at 1-6 08:22
No, in RTH it does not pitch down to 30 degrees, its as in P-GPS mode.

In RTH mode and pushing the stick fully fwd will increase speed (thus more pitch down)

Why is it the case that RTH uses P-GPS mode and limits itself this way?  The drone can realize that it's not making progress and is losing to the wind so in such a situation why doesn't it automatically switch to sport mode or have a special P-GPS+RTH mode that would allow it to pitch more?

I lost mine yesterday after 22 hours of ownership. I took it in the backyard and intended to just keep it close as I knew it was windy. I flew a little higher than I meant, and tried to RTH. It said it couldn't due to high winds. It drifted out over some tall pine trees and lost connection. I drove around trying to regain connection, but was only able to do so briefly, and not long enough to get a position on it. The last image I received was from high atop a tree, somewhere.

Labroides Posted at 1-5 23:14
Your flight data looks like this: https://www.phantomhelp.com/LogViewer/2MSDZF0ZXXL3Y4KQJU8H/

You spent a lot of time around 600 feet altitude and the wind there was in the range that the drone could handle.

”At 10:34 you gave it full stick in Sport Mode but could only reach 16mph in a NW direction.”

This suggests to me the wind speed was c. 13 mph, so its airspeed was 29  mph.

It’s a small drone.  29 mph is fast for a 249 gram  craft. Wind is treacherous for small planes or boats.
If there’s a wind warning that’s all you need to know. You need to land.







It is a small craft

dingo_do Posted at 1-6 10:11
Why is it the case that RTH uses P-GPS mode and limits itself this way?  The drone can realize that it's not making progress and is losing to the wind so in such a situation why doesn't it automatically switch to sport mode or have a special P-GPS+RTH mode that would allow it to pitch more?

good question for DJI !

I think for drones with obstacle avoidance.....if you fly max speed OA does not work! Sensing distance to braking distance etc.

But as MM has no OA...but in RTH with aveverage speed it can fly longer time   i think.

cheers
JJB

So in theory, our little paperplane would be best to RTH in Sport mode and then we may all have a chance of getting our investment back when we encounter a technical issue?

not RTH fail, another operator failure, what a ridiculous height to be flying at

Dzulkernian747 Posted at 1-6 00:32
Gents, thank you for the data analysis. I have flow the drone in a much higher wind conditions (literally by the sea side) at higher altitude and still the drone is able to come home safely automatically. The day I lost the mini the wind was not as harsh, I am pretty confident the drone could have flown home through the calm breeze easily instead of fly further away once it looses the signal. I get strong wind warning a lot on the mini even when there is hardly any breeze. I guess just have to wait for DJI's official reply on this case......

At the risk of upsetting you, you're just being stubborn here. There's no possible way you could know what the wind speed was at almost 900ft, the wind at ground level is irrelevant. Furthermore, the log clearly shows wind being a problem. For instance at 6:35 you're full right stick backwards in Sport mode and the Mini is doing just 10-11mph instead of the 28mph it should be doing. This suggests a significant wind at that altitude, 17-18mph at least. And that was at 580ft. You then climbed to 880ft! Keep in mind the max speed in P mode (the mode used by RTH) is just 18mph so you're already in trouble, even at this "low" altitude of 580ft. Furthermore, while being blown backwards  by the wind in RTH mode (14:50) you can see the mini is pitched down, trying to fly forward. It is however moving backwards. No other explanation than wind. If it was RTH going crazy, the drone would be pitched up to fly backwards (like in the previous 6:35 example).
The log is pretty clear, this was pilot error, the drone did nothing wrong.

Ice_2k Posted at 1-6 14:43
At the risk of upsetting you, you're just being stubborn here. There's no possible way you could know what the wind speed was at almost 900ft, the wind at ground level is irrelevant. Furthermore, the log clearly shows wind being a problem. For instance at 6:35 you're full right stick backwards in Sport mode and the Mini is doing just 10-11mph instead of the 28mph it should be doing. This suggests a significant wind at that altitude, 17-18mph at least. And that was at 580ft. You then climbed to 880ft! Keep in mind the max speed in P mode (the mode used by RTH) is just 18mph so you're already in trouble, even at this "low" altitude of 580ft. Furthermore, while being blown backwards  by the wind in RTH mode (14:50) you can see the mini is pitched down, trying to fly forward. It is however moving backwards. No other explanation than wind. If it was RTH going crazy, the drone would be pitched up to fly backwards (like in the previous 6:35 example).
The log is pretty clear, this was pilot error, the drone did nothing wrong.

Thank you for your observation and analysis, yes I guess I am being a bit stubborn in believing its entirely a pilot error and the drone is working as per design. As mentioned before I have flew my mini in very harsh wind condition by the seaside and it have managed to come home safely - that's a confidence builder there. I guess this incident is just one of those days where everything just went sideways. I'll wait for DJI's official reply before I start selling batteries, controllers and prop guards.

Labroides Posted at 1-5 23:14
Your flight data looks like this: https://www.phantomhelp.com/LogViewer/2MSDZF0ZXXL3Y4KQJU8H/

You spent a lot of time around 600 feet altitude and the wind there was in the range that the drone could handle.

Thank you Labroides for the very details flight log interpretation, that will indeed help a lot as I discussed further with DJI on why the drone flew further away after RTH was activated. Thank you for you support.

Hi,

did you guys realize that the drone went into "auto landing mode" at 17m 3s (744.1ft, 3.1mph drift speed)  and stopped drifting at 17m 7.5s (4.5 s later !)  at an altitude of 717.8ft  ???? That suggests that auto landing mode made it stop driftig while the drone was still at the great heights where it was driftig before ! During the whole auto landing descent it had 0 drift!!!!  I do not believe that the wind stopped at exact the same time the drone went into auto landing mode. This is clearly  an algorithm problem!

And take a look at the similarity (zick-zack) of the "drift patterns" from Dzulkernian747 and another user (Akrasky) from the forum who has also lost his drone with the drift problem:



  

Greetings,
Lops

Lops Posted at 1-7 01:38
did you guys realize that the drone went into "auto landing mode" at 17m 3s (744.1ft, 3.1mph drift speed)  and stopped drifting at 17m 7.5s (4.5 s later !)  at an altitude of 717.8ft  ???? That suggests that auto landing mode made it stop driftig while the drone was still at the great heights where it was driftig before ! During the whole auto landing descent it had 0 drift!!!!  I do not believe that the wind stopped at exact the same time the drone went into auto landing mode. This is clearly  an algorithm problem!

When it starts descending, some of the power previously used for maintaining altitude can now be used for flying forward. Given the fact that it was previously just being pushed backwards by 4-5mph while also maintaining altitude, it makes sense that the added power is now just enough to allow it to keep position. If you look at the pitch angle, the drone stays significantly pitched down during descent, showing it's still fighting the wind.

Ice_2k Posted at 1-7 01:48
When it starts descending, some of the power previously used for maintaining altitude can now be used for flying forward. Given the fact that it was previously just being pushed backwards by 4-5mph while also maintaining altitude, it makes sense that the added power is now just enough to allow it to keep position. If you look at the pitch angle, the drone stays significantly pitched down during descent, showing it's still fighting the wind.

Makes sense. That would mean that wind was still there and that there is an upper power consumption limit for the motors which was too low or insufficient for RTH. The question is then if it could be better to increase the power limit in the case of RTH and away-drift. I understand that this would have technical limits. But i guess there is margin that could be used for these emergency cases. Is it better to completely loose  the drone or to risk damages on the system due to over-powering it a bit ?  For the latter the pilot would at least have a chance to get the drone back...

Ice_2k Posted at 1-7 01:48
When it starts descending, some of the power previously used for maintaining altitude can now be used for flying forward. Given the fact that it was previously just being pushed backwards by 4-5mph while also maintaining altitude, it makes sense that the added power is now just enough to allow it to keep position. If you look at the pitch angle, the drone stays significantly pitched down during descent, showing it's still fighting the wind.

Why did the drone maintains altitude when RTH is activated (resulting to a drift/flyaway) instead of start descending while the battery was still at 44%? If the drone could holds its position in auto landing mode it could have done the same while its neaeby the homepoint.  Both scenarios are in RTH mode anyway. The safeguarding logic should be to get to home point when something goes wrong.

Because the drone never descends in RTH mode until it reaches the home point. Or obviously until the battery is critically low as happened here and it just lands where it is. The safeguard logic *is* to go to HP when something goes wrong. That doesn't mean it can break the laws of physics and battle winds faster than its top speed. Nor does it mean it will take decisions such as descending *while* flying towards the HP as that would create more problems than it would solve, imagine flying into a building when RTH was initiated at an altitude that would have cleared the building and the drone then decided to descend while flying back. It's not an AI and it has no collision sensors, there's no "perfect" way to implement this logic.

Sorry for your loos. Too high and too windy, maybe something can be improved from DJI, but all in all one should avoid windy scenarios specially out of VLOS.

Frankly I do believe there's a problem with the RTH logic. It should be able to return to home using as much tilt as it is physically possible since one doesn't trigger the RTH for fun and is most likely in a panic situation. Also not least because RTH is usually set quite higher up on purpose where winds are stronger. It would make zero sense that the drone rushed home but also makes no sense the drone is not using all it's got to get home.

m80116 Posted at 1-7 12:28
Frankly I do believe there's a problem with the RTH logic. It should be able to return to home using as much tilt as it is physically possible since one doesn't trigger the RTH for fun and is most likely in a panic situation. Also not least because RTH is usually set quite higher up on purpose where winds are stronger. It would make zero sense that the drone rushed home but also makes no sense the drone is not using all it's got to get home.

Not sure if the tech is there for Mavic mini to measure wind and set it’s propulsion to cope with what the wind throws at it , yes it would be great but I think it’s impossible for Mavic mini, for craft like Mavic 2 and Mavic air in Rth craft is able to turn off obstacle avoidance to create a steeper pitch, it’s still not fool proof if wind is stronger then results will be the same.

Mavic mini has limits which are very clear as regards flying in wind and with a small bit of knowledge about the direction and strength of the wind the pilot should be able to make decision’s before he flys, some will take chances others will be conservative but all should accept responsibility for their actions.

If craft for some reason malfunctions then dji should accept responsibility.

I’m sure if and when we see a mini 2 there will be improvements because tech will be more available and better priced.
I am an experienced drone pilot and I wouldn’t entertain some of the winds I see people flying with Mavic mini and throw inexperience into the mix.
If you come back here in 6 months you will see a lot less of this because experience plays a big part in this.

can someone share some info on how to read the tilt angle data from the flight data log...I assume its pitch value, + means the drone tilting up (backward motion) while - means the drone is tilting down (forward motion) ?

and what does this represent : Max Service Ceiling Above Sea Level @ 3000 m ?

Mini lacks the tech/AI of other advance higher priced DJI big brother drones hence the low price point, that is understandable however DJI should have made the logic in a way that if the drone is not moving forward during RTH then is should descends and land on or  at that point rather then drift further away - anyone agree with this logic ? This is not advance AI after all the mini has GPS lock capabilities.... maybe give it 10 seconds to move to home point, if its not moving (using GPS coordinate from current position vs home point - the same basis for RTH program) then start descending and land immediately....at least I will still stand a chance to maybe regaining transmission or even if it falls I would still be able to find it easily if its near by. That would be better rather then keeping flying far away and still crash into something during emergency landing, even worst drifting away in No Flyzones....yikes.  Crashing into an obstacle/building is inevitable in any case of emergency landing due to lost of transmission.

Dzulkernian747 Posted at 1-7 16:39
can someone share some info on how to read the tilt angle data from the flight data log...I assume its pitch value, + means the drone tilting up (backward motion) while - means the drone is tilting down (forward motion) ?

and what does this represent : Max Service Ceiling Above Sea Level @ 3000 m ?

Dzulkernian747 Posted at 1-7 16:39
can someone share some info on how to read the tilt angle data from the flight data log...I assume its pitch value, + means the drone tilting up (backward motion) while - means the drone is tilting down (forward motion) ?

and what does this represent : Max Service Ceiling Above Sea Level @ 3000 m ?

Your understanding of pitch angle is correct.

what does this represent : Max Service Ceiling Above Sea Level @ 3000 m ?
It means if you climb a mountain more than 3000 metres high and launch from there, you can't expect your drone to fly properly.

DJI should have made the logic in a way that if the drone is not moving forward during RTH then is should descends and land on or  at that point rather then drift further away - anyone agree with this logic ?

DJI's RTH programming is simple and efficient.
It's easy to understand and it works well.
Pilots of flying machines need a certain level of understanding and awareness even when they are not inside their aircraft.

You lost your drone from a combination of a problem with the Mini sometimes not flying properly, and a complete lack of awareness of what was happening to your tiny, toy drone or what actual wind speeds might be 800 feet up.
All you had to do was bring it down and you'd still have your lost Mini.

Another question, what does it mean when the log remarks says RTH heading alignment ? is that when the drone starts to assess the direction/trajectory to the home point ?

Dzulkernian747 Posted at 1-7 19:27
Another question, what does it mean when the log remarks says RTH heading alignment ? is that when the drone starts to assess the direction/trajectory to the home point ?

It means the drone is turning to point towards the home point

Labroides Posted at 1-7 19:48
It means the drone is turning to point towards the home point

Noted, I guess that is when the tiny toy drone decides it is time to turn around towards the direction of the nest.

DJI have only blooooof warranty policy
I lost my drone mavic 2 zoom,
RTH problem with 21 sattalit full RC.S

after 20 email and dji thinks the users is DANNKY!!!!!
my last things is that the DJI must be, specially supervisor they must decide from section bellow :
1- or make me the replacement as new without RC and charger
2- or send me the refurbished drone
3- to find my drone,Dji build it the piece of technology, GNSS gps technology, to support drone to home point after losing signal with RC or when you push to RTH. they have also this technology to go inside the gps number as builded in drone, or program from them technology to see where is the drone or what happened, because after lost signal the drone management under gps support, but not coordinate from flight recorder because after lost signal the flight record will be stop recording as lost signal coordinate I have too this coordinate.


if not resolve it I do with my lawyer hardest as possible to complaint DJI

REGARDS SASAN

fans96706bd1 Posted at 11-21 16:29
DJI have only blooooof warranty policy
I lost my drone mavic 2 zoom,
RTH problem with 21 sattalit full RC.S

Sasan ... without flight data, we cannot tell what happened to your drone.
If you want attention, post the .txt file from your flight data and we'll be able to see what the problem really was.