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Mavic Mini suddenly landed without giving command
5831 28 2020-2-16
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djiuser_UfMEMweKUfRJ
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Hello,

I am currently in the alps on winter sports. I was flying my drone at the mountain at 10.30 at around 2000m above sea level. I was flying for about 6 minutes, and had just made a helix quickshot. After the quickshot it was automatically returning to home, but suddenly it stopped moving forward, and began landing. I couldn't cancel it on my phone, and tried to rise the drone again with my controller, but it didn't responded to my commands and was landing at the current location (in the snow). I was very lucky that the drone was nearby and that it didn't started to land above the canyon. I picked the drone up from the snow and started to clean it right away.

I checked the FlightRecord made from the flight, and compared it to a other flight with normal landing. In the flight were it went wrong it said in the flightrecord: "Adv landing", but in the log of the normal landing it just said "Forced landing" (that was a good landing). How is it possible that my drone was landing automatically without command?

Online logviewer of flight: https://www.phantomhelp.com/LogViewer/BD3O76BA6OWE6WV0RLJS/
In the online logviewer you can see my right joystick move up when it suddenly started landing, my right joystick have I set to control the altitude. My left joystick is set to control the position.
I added the FlightRecord of the flight in the attachment of this post.

What could be the cause of the automatic landing?
Could I avoided this automatic landing? Or is my Mavic Mini a factory fault?

Thank you in advance.


FlightRecord.zip

782.1 KB, Down times: 6

Flightrecord of the flight were it suddenly landed without giving a command

2020-2-16
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DJI Stephen
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Hello and good day. I am sorry for the trouble this has caused and thank you for reaching out. May we know the condition and the temperature when you flew your DJI Mavic Mini and may we also know if it was foggy that time when you flew the said drone? The temperature and the location condition might have affected sensors of the said drone that is why it landed that way. Thank you.
2020-2-16
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djiuser_UfMEMweKUfRJ
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DJI Stephen Posted at 2-16 09:28
Hello and good day. I am sorry for the trouble this has caused and thank you for reaching out. May we know the condition and the temperature when you flew your DJI Mavic Mini and may we also know if it iswas foggy that time when you flew the said drone? The temperature and the location condition might have affected sensors of the said drone that is why it landed that way. Thank you.
Hello Stephen,

The temperature was around 10 degrees celcius. There was little to no wind. The weather was clear with no fog. What could be the reason it suddenly landed?
2020-2-16
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Francoisd
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France
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Hi,
After seen you logs in airdata, I can see you have a lot of "not enough power" error messages. The temperature where you were was not so high in altitude and I guess you perhaps had propeller freeze which made your MM loosing altitude.
2020-2-16
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Spark_Pilot_XxXx
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Germany
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Francoisd Posted at 2-16 10:06
Hi,
After seen you logs in airdata, I can see you have a lot of "not enough power" error messages. The temperature where you were was not so high in altitude and I guess you perhaps had propeller freeze which made your MM loosing altitude.

Nah, i dont think so because of this "landing" mode in the log...
2020-2-16
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Maxwooze
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France
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I had same problem. Mavic Mini landed in seawater...I could reach my aircraft and sent to DJI but I tried couple days ago to fly on a field and Mavic Mini want to land sometimes (no wind, good weather). I am not really self-assured now! Maybe updates will fix it if DJI understand the problem.
2020-2-16
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DJI Stephen
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djiuser_UfMEMweKUfRJ Posted at 2-16 09:37
Hello Stephen,

The temperature was around 10 degrees celcius. There was little to no wind. The weather was clear with no fog. What could be the reason it suddenly landed?

Thank you for the additional information you have shared with us. For us to be able to isolate the said issue. Can you please try to fly your DJI Mavic Mini to a different location and condition just to see if the issue will still persist? Please keep us posted for us to be able to assist you further. Thank you.
2020-2-16
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rwynant V1
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So,  cold is not good for power output of a Lithium Battery.

At the end, the Battery % shows 59%.  Based on the cell voltage that is incorrect.  59% the cell voltage should have been at 3.81 to 3.84 per cell.....NOT 3.65v per cell

I am thinking the "system" knew it was in a low voltage situation and simply chose to land before it crashed due to no power.  

3.65volts per cell should be reading  20% to 24% approximately........

Randy
2020-2-16
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djiuser_UfMEMweKUfRJ
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rwynant V1 Posted at 2-16 15:01
So,  cold is not good for power output of a Lithium Battery.

At the end, the Battery % shows 59%.  Based on the cell voltage that is incorrect.  59% the cell voltage should have been at 3.81 to 3.84 per cell.....NOT 3.65v per cell

Hello Randy,

Thanks for your reply.
Why would it show the wrong battery percentage? And shouldn’t it give me a message that it’s going to land. Even at 20% it should not land suddenly.
2020-2-16
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djiuser_UfMEMweKUfRJ
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DJI Stephen Posted at 2-16 14:16
Thank you for the additional information you have shared with us. For us to be able to isolate the said issue. Can you please try to fly your DJI Mavic Mini to a different location and condition just to see if the issue will still persist? Please keep us posted for us to be able to assist you further. Thank you.

Hello Stephen,

I flew at other places without any trouble. So it’s just that one flight in the mountains.
2020-2-16
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InspektorGadjet
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Were the batteries freshly charged?
I had one of my three batteries in the battery hub for 3 weeks, and it showed 98% however it got drained much faster than the other two.
Something to consider.
2020-2-17
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djiuser_UfMEMweKUfRJ
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InspektorGadjet Posted at 2-17 01:31
Were the batteries freshly charged?
I had one of my three batteries in the battery hub for 3 weeks, and it showed 98% however it got drained much faster than the other two.
Something to consider.

The batteries were 100% fully charged
2020-2-17
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Renato61
First Officer
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Italy
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I think that whatever the reason for the forced landing, this should appear on the app and especially in the log.
Understanding the possible error serves not to repeat it.
2020-2-17
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Nidge
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rwynant V1 Posted at 2-16 15:01
So,  cold is not good for power output of a Lithium Battery.

At the end, the Battery % shows 59%.  Based on the cell voltage that is incorrect.  59% the cell voltage should have been at 3.81 to 3.84 per cell.....NOT 3.65v per cell

The Mavic Mini Battery pack is made up of 2 Samsung IMR 18650 25R cells, wired in series. Each cell has a maximum discharge current of 20A and a maximum pulse current of 100A, but as they are connected in series this is 20A@nominal voltage of 7.2 Volt. Due to the chemistry of these cells they can be safely discharged to a minimum level of 2.5Volt/cell.

The issue may lie within the Battery Monitor Module, the device within the battery pack that acts to balance the cells while they are charging and also sends battery information  to the the MM’s main processor.

I recently came across three new Phantom batteries that exhibited the exact same behaviour. The batteries were charged to 100%. The software showed full capacity and each cell was at the expected voltage. However when in flight the Phantom decided to auto-land after a few minutes  claiming the battery was at less than 15%.

However... back on the bench the software was claiming the battery was at 69%  with an average cell voltage of 3.9Volt.

I manually discharged the battery while connected to the monitoring software. Part way through the discharge process the battery was claiming 0% charge while the cells were still at an average of 3.8Volt per cell. I continued the discharge process until the terminal Voltage of the battery pack was at around 10.2Volt or 3.3Volt Per cell. Next a full charge of the battery pack was done followed by a test flight. This time a sustained flight of around 25minutes was accomplished ending with a no load terminal voltage of 11Volt.  I performed the same procedure with the other two batteries and they both returned a flight time of around 25minutes.

Quite often “Smart” batteries are not really that smart.

Nidge.
2020-2-17
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Guorium
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Thanks for uploading the log. I had a look. Two things.

At 3965 the drone came to a full stop while in Quickshot RTH. You say it was a helix QS. On the map, I do not think the post-QS return was even triggered. The drone just switched out of QS and to P mode then started dropping immediately. Is that what you saw?

The second thing is your stick did not work somehow at the start of the drop but somehow the last moment worked. See the very end of the record the altitude (the yellow part) and vertical speed both shot up as you applied the final stick up. Is that what you saw happened?
2020-2-17
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virtual
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djiuser_UfMEMweKUfRJ Posted at 2-16 22:50
Hello Randy,

Thanks for your reply.

Why would it show the wrong battery percentage? And shouldn’t it give me a message that it’s going to land. Even at 20% it should not land suddenly.

The discharge cycle of battery is slightly affected with cold weather (lower voltage and drains faster), but 3,65V should be safe voltage, no need for prompt landing at this level.
As there are issues reported with S-mode behaviour, I would suggest to not use S-mode in mountains and winter conditions.
You say "After the quickshot it was automatically returning to home" so you pressed RTH button? As it was around 60ft distance and within 20m range RTH autolands immediately... It doesn't answer why it wasn't possible to cancel the landing...
2020-2-17
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djiuser_UfMEMweKUfRJ
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virtual Posted at 2-17 04:15
Why would it show the wrong battery percentage? And shouldn’t it give me a message that it’s going to land. Even at 20% it should not land suddenly.

The discharge cycle of battery is slightly affected with cold weather (lower voltage and drains faster), but 3,65V should be safe voltage, no need for prompt landing at this level.

Thanks for the reply and the explanation. After the quickshot it showed a message like “Quickshot done, automatically returning to home” (I’m not sure if it said ‘to home’ at the end). I didn’t press the RTH button.
2020-2-17
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djiuser_UfMEMweKUfRJ
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Guorium Posted at 2-17 03:21
Thanks for uploading the log. I had a look. Two things.

At 3965 the drone came to a full stop while in Quickshot RTH. You say it was a helix QS. On the map, I do not think the post-QS return was even triggered. The drone just switched out of QS and to P mode then started dropping immediately. Is that what you saw?

Hello,

Thank for your reply. While the drone was landing it didn’t react to my joystick, it just kept landing. It wasn’t rising at the end.
2020-2-17
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djiuser_UfMEMweKUfRJ
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Guorium Posted at 2-17 03:21
Thanks for uploading the log. I had a look. Two things.

At 3965 the drone came to a full stop while in Quickshot RTH. You say it was a helix QS. On the map, I do not think the post-QS return was even triggered. The drone just switched out of QS and to P mode then started dropping immediately. Is that what you saw?

Hello,

Thank for your reply. While the drone was landing it didn’t react to my joystick, it just kept landing. It wasn’t rising at the end.
2020-2-17
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djiuser_UfMEMweKUfRJ
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Guorium Posted at 2-17 03:21
Thanks for uploading the log. I had a look. Two things.

At 3965 the drone came to a full stop while in Quickshot RTH. You say it was a helix QS. On the map, I do not think the post-QS return was even triggered. The drone just switched out of QS and to P mode then started dropping immediately. Is that what you saw?

Hello,

Thank for your reply.
A moment after the quickshot it immediately landed and didnt react to my commands.

While the drone was landing it didn’t react to my joystick, it just kept landing. It wasn’t rising at the end.

What software do you use to analyse these flightrecords?

Thank you in advance
2020-2-17
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JJB*
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Hi

Had a look at your flight too, sorry for your unexpected landing.

In your log lot of  messages, see chart.

"High altitude. Aircraft braking distance increased and flight time decreased. Fly with caution"
"Aircraft max power load reached. Decrease altitude and fly with caution. If this issue persists, Land immediately | High altitude. Aircraft braking distance increased and flight time decreased. Fly with caution"
"Strong wind warning. Aircraft unable to fly stably. Lower altitude immediately and manually Return to Home"

I am not sure how heigh a MM will climb in this kind of quickshot, but i did not went as high as i would expected.
When the quickshot was ended it tried to fly to the start position.
This was stopped beacuse you move a control stick, this ended the quickstop flying to start position.
But as you see in the chart, your MM was not able to fly to the start position, it went backwards.
Not enough power to fly forward and keep height, so it dropped down.

BTW  "NaviAdvLanding" is an error in decrypting log files, it should read "Quickshot".
PS https://forum.dji.com/thread-203659-1-1.html as answer to your question previous post.

cheers
JJB


analysis1.png
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2020-2-17
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djiuser_UfMEMweKUfRJ
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Hello,

Today I was flying again with my Mavic Mini, and the same behavior began. At 60% battery the drone gave the error: "Max power load reached", and started to lose altitude. It tipped the ground 2 times and the drone just managed to come back. I googled for "Mavic mini max power load reached" and saw that many other people had the same issue as me (especially people flying on high height relative to sea level, just like me).

Forum post: https://forum.dji.com/thread-203224-1-1.html
YouTube video: https://www.youtube.com/watch?v=OpumxfV-KeE

It seems like the propellors on early produced Mavic Mini are bended or something. Most of the people fixed this issue by replacing the propellors with the ones from the fly more combo. I have replaced my propellors with these and will send an update if this "suddenly landing" issue still persists or not.
2020-2-18
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HedgeTrimmer
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djiuser_UfMEMweKUfRJ Posted at 2-18 12:41
Hello,

Today I was flying again with my Mavic Mini, and the same behavior began. At 60% battery the drone gave the error: "Max power load reached", and started to lose altitude. It tipped the ground 2 times and the drone just managed to come back. I googled for "Mavic mini max power load reached" and saw that many other people had the same issue as me (especially people flying on high height relative to sea level, just like me).

Do hope replacing original Prop paired blades, with spare paired blades resolves your problem!
Happy Droning!
2020-2-18
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djiuser_UfMEMweKUfRJ
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I replaced my propellors yesterday, and made today a flight in the exact same conditions without any problem! Not even a single time the "Max power load reached" error. I also got the feeling that my drone is faster now and the flight time is longer. So if you experience the "Max power load reached" error, and it's landing suddenly, just replace all propellors with the ones from the fly more combo. I really think that DJI had to inform us about this problem, what could have prevented a lot of crashes.
2020-2-20
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hallmark007
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djiuser_UfMEMweKUfRJ Posted at 2-20 07:16
I replaced my propellors yesterday, and made today a flight in the exact same conditions without any problem! Not even a single time the "Max power load reached" error. I also got the feeling that my drone is faster now and the flight time is longer. So if you experience the "Max power load reached" error, and it's landing suddenly, just replace all propellors with the ones from the fly more combo. I really think that DJI had to inform us about this problem, what could have prevented a lot of crashes.

That sounds positive, hopefully others might have similar experience .

I agree it’s probably up to dji to do testing if they haven’t already and issue appropriate warnings, I think for many here there are all sorts of theories from the daft to the ridiculous being touted , it really wasn’t until Labroids brought prop issue to people’s attention that people started looking to hardware as the problem, hopefully there is something in this as a permanent fix .
2020-2-20
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JJB*
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djiuser_UfMEMweKUfRJ Posted at 2-20 07:16
I replaced my propellors yesterday, and made today a flight in the exact same conditions without any problem! Not even a single time the "Max power load reached" error. I also got the feeling that my drone is faster now and the flight time is longer. So if you experience the "Max power load reached" error, and it's landing suddenly, just replace all propellors with the ones from the fly more combo. I really think that DJI had to inform us about this problem, what could have prevented a lot of crashes.

Great feedback!  amazing what original brand new blades can do somehow.

Do you see or feel any difference with the new installed blades and the old ones?

cheers
JJB

2020-2-20
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djiuser_UfMEMweKUfRJ
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JJB* Posted at 2-20 08:02
Great feedback!  amazing what original brand new blades can do somehow.

Do you see or feel any difference with the new installed blades and the old ones?

Hello,

I can't compare them side by side anymore, but I thought the original ones were more bended and got a larger curve.
2020-2-20
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JJB*
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djiuser_UfMEMweKUfRJ Posted at 2-20 08:06
Hello,

I can't compare them side by side anymore, but I thought the original ones were more bended and got a larger curve.

oke, my MM does perform OKE but still i will check and a see if there is any difference with my spare set of blades.

cheers
JJB
2020-2-20
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djiuser_UfMEMweKUfRJ
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JJB* Posted at 2-20 08:09
oke, my MM does perform OKE but still i will check and a see if there is any difference with my spare set of blades.

cheers

Hello,


I red that only some (I thought early produced) MM's got these old bad blades
2020-2-20
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