Mavic Mini Uncommanded Descent

[DLahr]

As I was setting up a shot above a river yesterday, AC suddenly descended from 64 feet to -4 feet (takeoff was at least 30-40 feet above water). I pushed up on the left stick as soon as I noticed and it immediately gained altitude.
I completed the shot and finished the flight without incident.
The odd thing about the whole episode is that it flew completely normally before and after, and pushing up on the left stick seemed to instantly correct whatever was going on.
Is this something I can expect to happen again, and would it be covered by warranty? Would I have to wait for it to actually crash before requesting replacement?
Airdata Log 5:34-5:50.

 

[Meta4]

Is this something I can expect to happen again, and would it be covered by warranty? Would I have to wait for it to actually crash before requesting replacement?

As well as the issue you noticed from 5:34.9 to 5:50.9 when the Mini lost 70 feet, altitude instability was happening earlier in the flight but not noticed.

After you finished descending at 5:02.4, your Mini was showing altitude stability issues, gaining and losing height with no corresponding joystick inputs.
After the incident that you noticed, you didn't leave the throttle for long enough to be sure that the issue had gone.

Altitude instability and uncommanded descents were a common issue early on with the Mini.
DJI fixed it after a while with Firmware 1.0.5.
Can you check the firmware version you have on the mini?
It looks like it's 1.0.244 but I'm not sure that it's displaying accurately in the data.

If it's earlier than 1.0.5 you need to update the firmware and changing the props wouldn't hurt.

 

[teeroy]

Between 1:20 and 2:50 it ascends from 11.2 ft to 76.8 without command to climb, if I'm seeing that right?

 

[Meta4]

Between 1:20 and 2:50 it ascends from 11.2 ft to 76.8 without command to climb, if I'm seeing that right?

From 1:20.3 to 2:39.3 there was a lot of altitude instability.
But from 2:39.4 it was climbing under RTH.

 

[teeroy]

From 1:20.3 to 2:39.3 there was a lot of altitude instability.
But from 2:39.4 it was climbing under RTH.

Good catch, thanks. I missed the RTH notice. I'm still pretty wet behind the ears reading these logs, I have lots to learn.

 

[DLahr]

Thanks for the analysis. The first ascent would explain why I lost VLOS around 2:20, I'm surprised I didn't notice but it might have been hard to distinguish between horizontal and vertical movement at that angle and facing into the sun. I triggered RTH to get it pointed toward me and probably assumed that the high altitude was due to RTH.
I do have a small strobe and landing gear mounted to the bottom which haven't caused any issues in the past.
Firmware version is 1.0.5.