DJI Mavic Mini Erratic Aircraft Behavior and Crash

[Diegus011]

Hi! Just wanted to share my experience in case someone else has had something similar happen to them. Last Sunday, I had ideal conditions with no wind up to 1000 ft, and beautiful clear skies for a 6:56AM sunrise flight in Newport Beach, California. I got a LAANC authorization to fly up to 100ft, and set off on a beautiful flight. Flew several passes along the bay (some footage included below) and the aircraft was performing perfectly. When I was down to about 40% battery, I took the aircraft out to fly a long shot along the jetty back to me. The mini was around 3000’ away, and while I was setting up the shot, it started moving on its own - it began with it drifting to the right about a hundred feet, followed by a descent that could not be arrested. No warnings or any other alerts on the screen. I started to try to come back, and the battery indicated 38%. On Sport mode and full throttle I was getting no forward motion, only sideways drift. There was absolutely no wind, and the drone was only about 30 ft high. At that point my main objective became to keep it over the narrow jetty as I battled with trying to get forward speed. The top speed I ever saw was about 7 mph. Then the drone started descending aggressively on its own as if it were in landing mode, however this was not announced in DJI Fly. Half the way on my journey back I got a low voltage warning, with the battery at 31%! I realized at that point that the drone just did not have enough voltage to fly at full throttle, and realized I was screwed! I tried to gain as much altitude as possible within my 100 ft ATC clearance, while I considered my options: An emergency landing over the jetty, or getting just low enough over the jetty to be able to track it accurately and trying to fly back following it. I settled on the second option. Several times the drone would drift, experience interference, descend on its own (at one point down to -3.7 feet!). I finally made it over the beach, when from 25 feet, it started an uncontrolled descent and finally pancaked onto the sand at a fairly high rate of descent. It still had about 20% battery left. A message was displayed "Aircraft Impact Detected"

Analysis on Airdata doesn't show an explanation of what may have caused the behavior. No errors or warnings. By the time the aircraft plummeted to the ground it was flying over land, so the "flying over water" canned explanation doesn't have a lot of traction for me.

I submitted the data to DJI for analysis so they are aware of this incident and hoping they have some insight.

Thanks!

 

[Thomas B]

Hi! Just wanted to share my experience in case someone else has had something similar happen to them. Last Sunday, I had ideal conditions with no wind up to 1000 ft, and beautiful clear skies for a 6:56AM sunrise flight in Newport Beach, California. I got a LAANC authorization to fly up to 100ft, and set off on a beautiful flight. Flew several passes along the bay (some footage included below) and the aircraft was performing perfectly. When I was down to about 40% battery, I took the aircraft out to fly a long shot along the jetty back to me. The mini was around 3000’ away, and while I was setting up the shot, it started moving on its own - it began with it drifting to the right about a hundred feet, followed by a descent that could not be arrested. No warnings or any other alerts on the screen. I started to try to come back, and the battery indicated 38%. On Sport mode and full throttle I was getting no forward motion, only sideways drift. There was absolutely no wind, and the drone was only about 30 ft high. At that point my main objective became to keep it over the narrow jetty as I battled with trying to get forward speed. The top speed I ever saw was about 7 mph. Then the drone started descending aggressively on its own as if it were in landing mode, however this was not announced in DJI Fly. Half the way on my journey back I got a low voltage warning, with the battery at 31%! I realized at that point that the drone just did not have enough voltage to fly at full throttle, and realized I was screwed! I tried to gain as much altitude as possible within my 100 ft ATC clearance, while I considered my options: An emergency landing over the jetty, or getting just low enough over the jetty to be able to track it accurately and trying to fly back following it. I settled on the second option. Several times the drone would drift, experience interference, descend on its own (at one point down to -3.7 feet!). I finally made it over the beach, when from 25 feet, it started an uncontrolled descent and finally pancaked onto the sand at a fairly high rate of descent. It still had about 20% battery left. A message was displayed "Aircraft Impact Detected"

Analysis on Airdata doesn't show an explanation of what may have caused the behavior. No errors or warnings. By the time the aircraft plummeted to the ground it was flying over land, so the "flying over water" canned explanation doesn't have a lot of traction for me.

I submitted the data to DJI for analysis so they are aware of this incident and hoping they have some insight.

Thanks!

Maybe post the flight data here for a quicker expert opinion by one of our members who does it a lot. Would be of aid to the community.

 

[Fly Dawg]

Analysis on Airdata doesn't show an explanation of what may have caused the behavior. No errors or warnings. By the time the aircraft plummeted to the ground it was flying over land, so the "flying over water" canned explanation doesn't have a lot of traction for me.

Share the Airdata link here and we can do a more detailed look. This may also require the device .dat file as well.

 

[Diegus011]

As a follow up, here is some footage from the flight:

 

[Diegus011]

Not sure if this is a valid way of sharing the data, but this is a link to airdata:

 

[GregE]

Wow- Nice videos
Very thorough writeup Hope you get it resolved

 

[Fly Dawg]

@Diegus011 That is correct, but you need to make it fully sharable. We need the original .txt log from there or you can upload the file here.

 

[Diegus011]

@Diegus011 That is correct, but you need to make it fully sharable. We need the original .txt log from there or you can upload the file here.

I show the file is setup to allow downloading the csv file. I see a CSV link under the map image. Are you able to see that? Maybe it knows it's me and thats why I can see it? I tried to upload the CSV directly but it didnt let me. Said it was an invalid file type for the site.

 

[Fly Dawg]

I tried to upload the CSV directly but it didnt let me. Said it was an invalid file type for the site.

Upload the "Original" .txt log here. And No we cannot see the file links on Airdata unless it is configured for sharing correctly. It is the .txt we need. Not the .csv

 

[Diegus011]

Upload the "Original" .txt log here. And No we cannot see the file links on Airdata unless it is configured for sharing correctly. It is the .txt we need. Not the .csv

Great! I just saw that the "Original" download puts out a text file. Trying to upload that now!

 

[Diegus011]

Here is the text file:

 

[Keule]

Upload the "Original" .txt log here. And No we cannot see the file links on Airdata unless it is configured for sharing correctly. It is the .txt we need. Not the .csv

Just download from the link given:

 

[Fly Dawg]

Just download from the link given:

The OP modified after the fact. It wasn't configured previously.

 

[Diegus011]

The actual file has been posted a couple of posts above. Let me know if there are any issues accessing! Thanks!!

 

[Fly Dawg]

@Diegus011 Ok, initial look, the uncommanded descents are obvious. This has been seen with the mini's a few times. If I recall correctly the only thing we could determine from the past data was a possible firmware bug. Nothing else in the data shows a real reason for the descents. I will comment on one thing. The VPS looks a bit odd, but I don't think that was the primary cause.

 

[Diegus011]

@Diegus011 Ok, initial look, the uncommanded descents are obvious. This has been seen with the mini's a few times. If I recall correctly the only thing we could determine from the past data was a possible firmware bug. Nothing else in the data shows a real reason for the descents. I will comment on one thing. The VPS looks a bit odd, but I don't think that was the primary cause.

View attachment 91125

Thanks for taking a look, Fly Dawg! I have seen a few other reports of similar incidents where the aircraft is behaving as if it were returning home, or landing, even though there is no indication anywhere that it is trying to do so. Maybe a bad unit? I generally had a lot of issues with the connection to the aircraft, even at short distances (under 1000 ft), but there didnt appear any connection issues on this particular flight.

 

[new2mavic]

This is likely to be another "motor power maxing out" case which has been reported several times here for the Mini. This time it also happened to the motors at the back.

At this point, full backward elevator was applied in sport mode. The nose tilted upward to about 22 degree ( see the attitude chart on the right ) and the craft flew backward at about 25 mph. This was perfectly normal.



Shortly afterwards, at about the same location, full forward elevator was applied but the craft did not tilt at all. Rapid drop in altitude also occurred here. Looks like the motors at the back have maxed out and failed to lift up the tail. This would trigger the flight controller to command the front motors to reduce power in order to get the nose down and the craft to fly forward. As the result, the power of all four motors became reduced hence the rapid descent.



The situation kept like that before the craft hit the sand. Full throttle was futile. It appears that the firmware cares more about achieving the commanded speed than maintaining the altitude.



I believe if the the craft was turned around and flown backward to the home point, it probably could land normally.

If the OP can share the .DAT file, more detailed reasons can be identified. Follow this thread to get the .DAT file : Flight log retrieval and analysis guide

 

[MaxE1955!]

I mean absolutely NO disrespect. However who would have been knowledgeable enough to know, without having previously seen the flight logs, to rotate the aircraft 180 degrees and fly the craft “backwards” to land safely? I don’t think even the techs from DJI would have that kind of skill set. Again, no disrespect to the poster, but I found that quite a puzzling response. Perhaps I simply misread the intent of the comment.

 

[geochd]

Hi! Just wanted to share my experience in case someone else has had something similar happen to them. Last Sunday, I had ideal conditions with no wind up to 1000 ft, and beautiful clear skies for a 6:56AM sunrise flight in Newport Beach, California. I got a LAANC authorization to fly up to 100ft, and set off on a beautiful flight. Flew several passes along the bay (some footage included below) and the aircraft was performing perfectly. When I was down to about 40% battery, I took the aircraft out to fly a long shot along the jetty back to me. The mini was around 3000’ away, and while I was setting up the shot, it started moving on its own - it began with it drifting to the right about a hundred feet, followed by a descent that could not be arrested. No warnings or any other alerts on the screen. I started to try to come back, and the battery indicated 38%. On Sport mode and full throttle I was getting no forward motion, only sideways drift. There was absolutely no wind, and the drone was only about 30 ft high. At that point my main objective became to keep it over the narrow jetty as I battled with trying to get forward speed. The top speed I ever saw was about 7 mph. Then the drone started descending aggressively on its own as if it were in landing mode, however this was not announced in DJI Fly. Half the way on my journey back I got a low voltage warning, with the battery at 31%! I realized at that point that the drone just did not have enough voltage to fly at full throttle, and realized I was screwed! I tried to gain as much altitude as possible within my 100 ft ATC clearance, while I considered my options: An emergency landing over the jetty, or getting just low enough over the jetty to be able to track it accurately and trying to fly back following it. I settled on the second option. Several times the drone would drift, experience interference, descend on its own (at one point down to -3.7 feet!). I finally made it over the beach, when from 25 feet, it started an uncontrolled descent and finally pancaked onto the sand at a fairly high rate of descent. It still had about 20% battery left. A message was displayed "Aircraft Impact Detected"

Analysis on Airdata doesn't show an explanation of what may have caused the behavior. No errors or warnings. By the time the aircraft plummeted to the ground it was flying over land, so the "flying over water" canned explanation doesn't have a lot of traction for me.

I submitted the data to DJI for analysis so they are aware of this incident and hoping they have some insight.

Thanks!

 

[geochd]

This seems a serious problem with Mini. Almost exact thing happened with me. I flew it from 7th floor of building. It updated home point about 200 ft away from me while midair at height of about 100 ft height. Flew further 500 ft away and when I brought back it refused forward motion beyond about home point. Was going sideways at slow speed, backward faster but never moved forward despite all tries. Thankfully I managed to land avoiding pool down below and recovered the aircraft. But it has shaken my confidence on this drone. Serious bugs in software. Didn’t fly it afterwards, will give it another try but serious improvement is required in this drone’s half cooked software.