It was a bit foggy today so I wanted to see if my Mini 2 could take a look around above it.  It took off and ascended vertically to about 40m at which point it was becoming not so easy to see so I decided that I should land it.  It was in Cine mode and there were no obstacles round so I used maxium defection of the joystick  to bring it down quickly.  This it did for the first couple of seconds but it then went into Landing Mode even though it was still at around 35m agl. It then appeared to hover or decend VERY slowly, still in landing mode.  I could see it reasonably clearly now. I could command the drone left/right, forward/back and up but it seemed committed to keeping in landing mode. Then after a few twiddles with the joysticks and maybe 60 seconds of trying to get out of landing mode it started to decend more normally again and I landed it without further drama.  I can only assume that the downward-looking landing sensors were affected by the mist and thought the drone was close to the ground even though it was at 35m but this is only a guess on my part.  Rc signal and GPS satellite signal strengths were fine, as was battery charge (90%).  It was cold though - close to freezing.

Has anyone had a similar experience and do you think my diagnosis is correct?  Anything else I should consider as the cause?

Thanks

Sounds correct, but sounds like some seriously thick fog. I have flown through fog on multiple occasions and after doing so I now advise against it. Flying through fog made my drone extremely wet and for me that is a huge no no! My Mini 2 flew through it like a champ each time however,, and I’ve never had the problem which you described but your assumption sounds reasonable . On a side note, I assume the mini 2 was made to withstand normal condensation that happens at various altitudes, but to go through mist or fog is something that invites unwarranted moisture and could lead  to problems. A quick pass through some fog should be ok but long flights should be avoided whenever possible.

Be careful in fog and near freezing temps as the props can ice up and cause crashes.

DRONEfactor27 Posted at 1-9 00:18
Sounds correct, but sounds like some seriously thick fog. I have flown through fog on multiple occasions and after doing so I now advise against it. Flying through fog made my drone extremely wet and for me that is a huge no no! My Mini 2 flew through it like a champ each time however,, and I’ve never had the problem which you described but your assumption sounds reasonable . On a side note, I assume the mini 2 was made to withstand normal condensation that happens at various altitudes, but to go through mist or fog is something that invites unwarranted moisture and could lead  to problems. A quick pass through some fog should be ok but long flights should be avoided whenever possible.

Thank you DRONEfactor27.  This all sounds like good advice re moisture which I had not considered before.  The drone wasn't wet when it returned but it was only a short flight of less than 2 minutes.  Perhaps the residual heat from being stored indoors was enough to prevent condensation in that time.
The fog wasn't super thick as I could still see the Mini 2 when it was at 40m alt, albeit rather, er, fogily.  The camera could also see the ground through the mist but again, mistily.   Thanks again.

DAFlys Posted at 1-9 01:26
Be careful in fog and near freezing temps as the props can ice up and cause crashes.

Ah!  That's a good point re prop icing DAFlys.  I measured +1C on the ground but its likely to have been less than that at altitude of course.  I appreciate your comments.  Thanks.

MiniGitmo Posted at 1-10 05:39
Ah!  That's a good point re prop icing DAFlys.  I measured +1C on the ground but its likely to have been less than that at altitude of course.  I appreciate your comments.  Thanks.

You're very welcome. - There was a article on Drone DJ covering how it can happen recently.

MiniGitmo Posted at 1-10 05:39
Ah!  That's a good point re prop icing DAFlys.  I measured +1C on the ground but its likely to have been less than that at altitude of course.  I appreciate your comments.  Thanks.

Heres a link to that article. - https://dronedj.com/2021/01/04/w ... crash-due-to-icing/

DAFlys Posted at 1-10 06:20
Heres a link to that article. - https://dronedj.com/2021/01/04/weather-matters-how-fog-caused-a-mini-2-drone-to-crash-due-to-icing/

Excellent!  Thank you.  It sounds very simial to my situation.  I think I was lucky.  Lesson learned.

MiniGitmo Posted at 1-10 23:13
Excellent!  Thank you.  It sounds very simial to my situation.  I think I was lucky.  Lesson learned.

No probs.  I flew in -1c and fog yesterday and didnt have any issues which makes me wonder if the M2P props are spinning slower than the mini props.

Hello there MiniGitmo. Thank you for reaching out and for these information you have given. Just a reminder that flying in heavy fog or clouds may make the gimbal wet, leading to temporarily failure. The gimbal will recover it's full function once it is dry. For reference I will post some Flight Environment Requirements. Again great work and fly safe always.

Thanks for the info DJI Stephen.  Much appreciated.

Hi minigitmo,
I just had the same. Was flying in the fog, could see it quite good at 84m and it only wants to go down in landing mode.
After a few minutes waiting, at +- 20m it was able to exit landing mode and recovered. The drone was a bit wet. Not really sure what happened because there was a good visual.

Thanks for sharing. The answer is interesting.

Hello, guys. I just had the same experience with a Mini 3. I took off from my balcony (it is quite big) on the 9th floor with the intention to rise above the fog. During takeoff I noticed my downward sensor was detecting 0.2m ot something to the ground when in fact it was already more than 40m. Nevertheless, I went up, took some photos and came down again. And then the battle began. In order to land, I usually have to adjust precisely the drone above my balcony in order to land perfectly. This time the drone was switching to Landing mode all the time. I was always canceling by moving it up or to the sides because I was afraid it will switch off the propellers at 40m height. Besides getting into Landing mode it would not react at all on command to descend. After 5 minutes of struggles and trying to cheat it to come down properly, I succeeded but I was already thinking of emergency landings on the roof or at some neighbour's balcony if battery went really low. Even though I was in heavy fog for at least 10 minutes at 5 deg C, the drone did not appear to be wet. Nevertheless I will think twice before repeating that adventure...

Do you know how the landing procedure works? How does the drone know when to turn off the props? Is it only sensor-related, or does it detect the altitude change via GPS as well?

Dji needs a turn off landing protection in fog bottom. Litchi app has this. Why you Fronting Dji. Stop trying to play your clients. Give us full control. Make that wind sensor gove drone more power. You can. Do it. Stop trying to wait till next model. Make drone repairable. Abs plastic Sucks stop drying it out for shipping.  Make brittle.

Dji needs a turn off landing protection in fog botton. Litchi app has this. Why you Fronting Dji. Stop trying to play your clients. Give us full control. Make that wind sensor gove drone more power. You can Do it. Stop trying to wait till next model. Make drone repairable. Abs plastic Sucks stop drying it out for shipping.  Make brittle. Cant wait for a modular phone and drone. One that don't end up garbage again in 5 years.