Signal stopped. RTH just landed (crashed)

[alopeznj]

I have a Mav Pro and thinking buying a Mini FOR MY 15 YO . But watching blogs Im skeptical now.

 

[Ptevee]

It was good but for sure a few issues.

 

[MAvic_South_Oz]

I have a Mav Pro and thinking buying a Mini FOR MY 15 YO . But watching blogs Im skeptical now.

Consider a Spark like this deal below, get a few batteries, and he has a great, very stable / tough first drone.

Blast From The Past! DJI Spark Combo DJI Official Refurb Sale

Spark is a tank compared to the mavic mini. A combo for only $369 https://djidroneservice.com/product/ID441C77/ Dji refurb w/ warranty dji care also available. Mint except for a black sticker on the outer box packaging

mavicpilots.com

 

[slup]

You can see what your flight data looks like in this short summary: DJI Flight Log Viewer - PhantomHelp.com

Your Mini was showing altitude instability earlier in the flight before you initiated RTH.
It started losing altitude from 3:51.2 then gained altitude without corresponding joystick input and started losing altitude again at 4:21.6 but recovered again.
You initiated RTH at 4:38.6 at 122 feet altitude.
It maintained altitude until 4:51.1 when it started losing altitude again.

At 4:50.5 it also stopped maintaining pitch which caused it to lose speed.

These are the two fatal flaws that too many Mavic Minis have been showing.
There's plenty of evidence there to support a warranty claim
Signal loss would have been due to the building between you and the drone, blocking your line of sight as the drone came lower.


It's a strong indication of the uncommanded descent problem that's caused the loss of many Minis .. and continues to.

Can you see uncommanded descent ?

Perhaps a confirmation of this, as if so DJI have been simply replacing under warranty.

Maybe @slup @sar104 @BudWalker will take a look too.

I agree fully with @Meta4 analysis ... this is again a very typical Uncommanded descent case for the Mini & should be honored as a legit HW failure by DJI.

It's clearly seen just after that the Elevator (Black dashed graph) stick is released, the Z-speed increase into positive direction, meaning descending (Blue graph).

Have in red circled the most pronounced occasions were this happens ... about 196sec into the flight the occasions were this happens increase to all elevator releases.

If we then look at the pitch angles (light blue graph) through out the flight ... in P-mode the Mini shall be able to go -20 degrees. The pitch never goes steeper then around -12 degrees at best ... this of course was reflected into a much lower heading speed then according to spec.

In the end, during the commanded RTH the pitch starts out with -14 degrees during a couple of seconds ... then pitch up to -2 to -4 degrees & there looses lift completely and the Mini goes down & ends up hitting ground with 2,4m/s.

If we had the DAT log we had seen the rear motors on max rpm's but not being able to sustain neither pitch or lift anyway.



When it comes to the "not enough force/ESC" error so are they not seen in the logs event stream, think those are created by Airdata. Instead a lot of messages regarding "High Altitude" ... this probably due to that the flight were conducted at 1950m ASL ... which for certain made this incident further likely to happen.

 

[maven4336]

It's mavic mini. I do have footage of the whole crash! Having trouble uploading it to my Google account today. I will post it shortly.

Very sorry, Iv seen way to many crashes for the mm

 

[sar104]

When it comes to the "not enough force/ESC" error so are they not seen in the logs event stream, think those are created by Airdata. Instead a lot of messages regarding "High Altitude" ... this probably due to that the flight were conducted at 1950m ASL ... which for certain made this incident further likely to happen.

FYI - the "not enough force" message is inferred from the OSD_isNotEnoughForce data in the txt log:

 

[LukiDrone]

I'm sorry for the crash, glad you recover it.
Keep us post about the results of the potential replacement/recall.

 

[Firejay27]

You can see what your flight data looks like in this short summary: DJI Flight Log Viewer - PhantomHelp.com

Your Mini was showing altitude instability earlier in the flight before you initiated RTH.
It started losing altitude from 3:51.2 then gained altitude without corresponding joystick input and started losing altitude again at 4:21.6 but recovered again.
You initiated RTH at 4:38.6 at 122 feet altitude.
It maintained altitude until 4:51.1 when it started losing altitude again.

At 4:50.5 it also stopped maintaining pitch which caused it to lose speed.

These are the two fatal flaws that too many Mavic Minis have been showing.
There's plenty of evidence there to support a warranty claim
Signal loss would have been due to the building between you and the drone, blocking your line of sight as the drone came lower.


It's a strong indication of the uncommanded descent problem that's caused the loss of many Minis .. and continues to.

You missed where it shows that the flight mode was changed from GO HOME back to P-GPS while it was still in the air. Either the software glitched and it switched modes or an accidental screen touch/button push told it not to go home anymore and go back to controlled P-GPS flight.

 

[sar104]

You missed where it shows that the flight mode was changed from GO HOME back to P-GPS while it was still in the air. Either the software glitched and it switched modes or an accidental screen touch/button push told it not to go home anymore and go back to controlled P-GPS flight.

It was cancelled by pressing the RC RTH button.

 

[Ptevee]

It was cancelled by pressing the RC RTH button.

The remote was not touched after signal lost. I've had several other incidents of RTH just dropping. Well far away from the 20 meter parameters.

 

[sar104]

The remote was not touched after signal lost. I've had several other incidents of RTH just dropping. Well far away from the 20 meter parameters.

You have misunderstood what happened. Signal was never lost during this flight - the entire flight up to motor stop is in the log.

You initiated RTH at 278 seconds with the RC button. It started to return home but at 290 seconds appears to have encountered the lack of thrust problem that has been plaguing some Minis, and began to descend. At 302 seconds RTH was cancelled by the RC button. At 305 seconds the aircraft landed in the tree and the FC shut down the motors, terminating the flight log.

 

[Ptevee]

I have submitted a warranty claim as fly away... I will post result's. Can DJI see all flights data? Or only data that I uploaded?

 

[Ptevee]

I don't understand that signal was never lost? All indicators on the RC and app said no signal?? Video was also gone?

 

[sar104]

I don't understand that signal was never lost? All indicators on the RC and app said no signal?? Video was also gone?

That must have been after it landed. The downlink was fine prior to that.

 

[sar104]

I have submitted a warranty claim as fly away... I will post result's. Can DJI see all flights data? Or only data that I uploaded?

They should replace it due to the uncommanded descent.

 

[MAvic_South_Oz]

They should replace it due to the uncommanded descent.

^^^ This, uncommanded descent . . .not flyaway.
Don't confuse them with the latter term.

 

[Ptevee]

You can see what your flight data looks like in this short summary: DJI Flight Log Viewer - PhantomHelp.com

Your Mini was showing altitude instability earlier in the flight before you initiated RTH.
It started losing altitude from 3:51.2 then gained altitude without corresponding joystick input and started losing altitude again at 4:21.6 but recovered again.
You initiated RTH at 4:38.6 at 122 feet altitude.
It maintained altitude until 4:51.1 when it started losing altitude again.

At 4:50.5 it also stopped maintaining pitch which caused it to lose speed.

These are the two fatal flaws that too many Mavic Minis have been showing.
There's plenty of evidence there to support a warranty claim
Signal loss would have been due to the building between you and the drone, blocking your line of sight as the drone came lower.


It's a strong indication of the uncommanded descent problem that's caused the loss of many Minis .. and continues to.

So the final results from DJI is that no crash happened and no probs found on flight data. They wanted me to buy a new drone due to "corrosion" on gimbal. This drone was 3 weeks old with 2 hours total flight time. So frustrated with DJI. I just had them return it. Hopefully I can clean up the gimbal??

 

[Ptevee]

Can you see uncommanded descent ?

Perhaps a confirmation of this, as if so DJI have been simply replacing under warranty.

Maybe @slup @sar104 @BudWalker will take a look too.

DJI did not cover this. Very disappointed in them. So many agreed that this should be a warranty replacement.

 

[MAvic_South_Oz]

So the final results from DJI is that no crash happened and no probs found on flight data. They wanted me to buy a new drone due to "corrosion" on gimbal. This drone was 3 weeks old with 2 hours total flight time. So frustrated with DJI. I just had them return it. Hopefully I can clean up the gimbal??

I wouldn't give up too easily.
Many front line on the phones etc will just say sorry etc . . . ask for it to be referred to a higher supervisor.

Firstly . . . if the analysis people can confirm definitive uncommanded descent, maybe you could refer DJI support people to this thread ?

 

[Ptevee]

I wouldn't give up too easily.
Many front line on the phones etc will just say sorry etc . . . ask for it to be referred to a higher supervisor.

Firstly . . . if the analysis people can confirm definitive uncommanded descent, maybe you could refer DJI support people to this thread ?

Thank you! I probably gave up too early. It's already on the way back to me. I just received my mavic 2 zoom yesterday which takes the bite out of mini problems, at least temporarily. If I experience the decent problems again I will send it back again. So far I am not happy with DJI.