Mavic Mini 'crash'

[Croxy]

Hello!

I'm as much a newbie as is possible I guess, so please bear with me! I took delivery of my first ever drone (Mavic Mini) on 19th March and almost lost it completely the following day. I took the Mavic to fly over a beach and water close by where I live. The weather was absolutely perfect, with no wind whatsoever, making my first flight easy. After practicing some basic manoeuvres, I noticed some seals basking in the sunshine on the opposite beach to where I was (an inlet to a loch), so I decided to set up my flight in front of the seals, over the water and perform one or more basic manoeuvres around them. My Mavic was hovering still, just above the water and ready for me to begin shooting video when suddenly I lost all contact with it and it disappeared into the water!! I tried for more than two hours to find the Mavic without success. I returned later in the day at low tide and thankfully, got lucky and found it! It was of course totally water damaged, but at least I was able to return it for replacement under the DJI Care Service plan. In doing so, I have now used a 'life' of that plan and so only have one replacement left, but hope that it won't be needed!

What concerns me, is DJI's analysis results of the flight log, which states as follows:

1. The aircraft was piloted under C mode and it responded to the pilot's control well;
2. Flight Time T=03:17 s, Relative Height H=4.5 m, the aircraft descended and flew forward after the pilot pushed forward the pitch with 78% and pulled down the throttle stick fully, then it crashed with obstacles;
3. The accident point: 57.9325711 -4.0079017.
According to the analysis, the incident was caused by misoperation. Please pay attention to the flight environment and fly with caution.

'Crashed with obstacles'? Impossible, as I was completely out in the open, over water with no obstacles even remotely in sight. A bird strike is the only possible explanation, if indeed it hit anything. The only thing I saw on screen, was a view of the seals as I got ready to video, then without any warning, a black screen, followed by a message 'IMU calibration required'. I've uploaded what I hope are the correct data files! I will be most grateful if someone could take a look and let me know what they think happened. Thanks!!

 

[old man mavic]

welcome to the forum,sorry the circumstances are not good, but i am sure our resident log experts will be along at some point to help you ,take care and fly safe

 

[Magilla Gorilla]

Welcome. Sorry you had such a bad first experience.
It sounds like they are referring to the water as obstacles.
Glad you found it.

 

[sar104]

The txt log shows some odd behavior at the end that really needs the mobile device DAT file to explain. Unfortunately the DAT file that you posted, although it has the correct index number, is from a flight 20 minutes earlier. Can you check if there is another FLY008.DAT?

 

[slup]

Just trying to decode Yaw, Roll & Pitch from the moment all uncommanded movements start it can be a prop/motor failure rear left 1163sec into the flight. But to prove/dismiss that it's a must to access the correct DAT.

 

[RayOZ]

A seal probably threw a stone at it for spying on it. ?

 

[Croxy]

Welcome. Sorry you had such a bad first experience.
It sounds like they are referring to the water as obstacles.
Glad you found it.

Thanks!

 

[Croxy]

welcome to the forum,sorry the circumstances are not good, but i am sure our resident log experts will be along at some point to help you ,take care and fly safe

Thank you, appreciated!

 

[Croxy]

The txt log shows some odd behavior at the end that really needs the mobile device DAT file to explain. Unfortunately the DAT file that you posted, although it has the correct index number, is from a flight 20 minutes earlier. Can you check if there is another FLY008.DAT?

Hi, FLY008.DAT is the very last DAT file that I have, therefore must represent the final flight of my Mavic?

 

[sar104]

Hi, FLY008.DAT is the very last DAT file that I have, therefore must represent the final flight of my Mavic?

As I mentioned above - the FLY008.DAT file that you posted above is for a different flight, at 0944 GMT on March 20. The flight in question was at 1004 GMT. So no - that file does not include the last flight.

 

[sar104]

Just to clarify what is in the txt log, in case the corresponding DAT file is not available, there is an apparent uncommanded descent at the end, recorded by both the IMU and the optical height sensor:



The unusual aspect is apparent when looking at the pitch, roll and yaw data:



The roll and yaw excursions after the elevator is centered are severe, and not typical of the oscillations seen in a more common MM uncommanded descent. Looking closer:



This looks much more like a lost prop or failed motor. Since there were no motor blocked messages I would lean towards the lost prop explanation, but there is nothing definitive to show that.

 

[Prismatic]

Just to clarify what is in the txt log, in case the corresponding DAT file is not available, there is an apparent uncommanded descent at the end, recorded by both the IMU and the optical height sensor:

View attachment 98366

The unusual aspect is apparent when looking at the pitch, roll and yaw data:

View attachment 98367

The roll and yaw excursions after the elevator is centered are severe, and not typical of the oscillations seen in a more common MM uncommanded descent. Looking closer:

View attachment 98368

This looks much more like a lost prop or failed motor. Since there were no motor blocked messages I would lean towards the lost prop explanation, but there is nothing definitive to show that.

I gather there weren't acceleration excursions to indicate a bird strike.

 

[sar104]

I gather there weren't acceleration excursions to indicate a bird strike.

The txt log doesn't contain the accelerometer data.

 

[Croxy]

Hi guys,

Many thanks for your input!

Having looked at the Flight Record folder from my phone, I note that I made 13 flights in all (unlucky for some!). There are 13 text documents (I've attached the last of these), but only 7 DAT files. I've attached a list of those to this post. Does this help?

 

[Croxy]

...... furthermore, this is the file that DJI sent back to me after I uploaded info to them.

 

[sar104]

Hi guys,

Many thanks for your input!

Having looked at the Flight Record folder from my phone, I note that I made 13 flights in all (unlucky for some!). There are 13 text documents (I've attached the last of these), but only 7 DAT files. I've attached a list of those to this post. Does this help?

That's the same txt log that you posted previously - it contains the crash data.

...... furthermore, this is the file that DJI sent back to me after I uploaded info to them.

That corresponds with the control data in the txt log, and the legend suggests that it is from the FLY008.DAT file that you posted. However - that flight is definitely not in FLY008.DAT unless DatCon has incompletely converted it, which seems unlikely.

 

[Croxy]

Thanks sar104. I hear what you're saying, but I only have the 7 DAT files in my FR folder as detailed in attachment earlier. I've not changed nor deleted any of the files contained within the FR folder. Curious!

Thanks to all of you who responded - this forum is an invaluable source of information and you experts are much appreciated by all I'm sure! I guess this will have to remain a mystery.

 

[sar104]

Thanks sar104. I hear what you're saying, but I only have the 7 DAT files in my FR folder as detailed in attachment earlier. I've not changed nor deleted any of the files contained within the FR folder. Curious!

Thanks to all of you who responded - this forum is an invaluable source of information and you experts are much appreciated by all I'm sure! I guess this will have to remain a mystery.

Yes - I realize that. But the end of that DAT record is at 10:01:55 GMT. The flight that ended with the crash started at 10:04:27 GMT. Either way - it still looks like a lost prop - were the props all attached when you recovered it?

 

[Keule]

But the end of that DAT record is at 10:01:55 GMT. The flight that ended with the crash started at 10:04:27 GMT.

I am wondering what data DJI has access to.
In the chart they sent the analysis the FLY008.DAT has an index. (and has events from beyond T=977s)



Any chance that the OP only has ...FLY008(0) or something like that?

 

[sar104]

I am wondering what data DJI has access to.
In the chart they sent the analysis the FLY008.DAT has an index. (and has events from beyond T=977s)

View attachment 98416

Any chance that the OP only has ...FLY008(0) or something like that?

It's certainly possible. I've seen that file nomenclature many times and I've never been quite sure what it means. @BudWalker may be able to shed some light on it.