My Susi (Mavic 2 Pro) is lost after Sudden Disconnect

[Barnes_de]

Hallo!

Unluckily, my first post in this forum is: my “Susi” (Mavic 2 Pro) is lost.

I was twice flying the drone on April 10th and had no problems on flight number 1. The battery was changed for a direct second take-off. 2 min into the second flight, I had a sudden signal loss (Camera and Controller) at a straight flight:

• see next Posts for *.txt and *.dat-files
• Unfortunately, there is no video.

First, I expected a return to home and kept calm. The RTH altitude setting was at 40m and no obstacle is higher than ~20m. After 10 minutes I went to the last known location and searched for about 2 hours. The plants on the surrounding fields were <25cm high. I also spoke to the farmer who was very gentle, and I left my contact details. Eventually, I gave up and the drone is lost.

Other considerations:

• The evening before I updated all devices to the latest firmware.
• The weather was fine.
• The signal loss appeared when I was looking down on the Smart Controller just when I intended to fly the drone on a right U-turn to bring it back closer.

The same day of the loss I contacted DJI. In the meantime, the technicians couldn't see the cause of the accident from the information from the provided log files. Their support offered a discount on a new purchase.

Thus, the only potential explanations I have from reading in this forum is that

1. the battery may have disconnected in flight. But then the drone should be close to the last known location. Or:
2. the drone had a flyaway with a fresh batterie.

I would really appreciate somes’ help: What might be the root cause and where could I search for Susi?

Also, to prevent it to happen again, I am planning the next drone to get a visible skin (neon orange or so) and a tracker (Loc8tor) and acoustic signal device (DroneKeeper micro). Are there other things you recommend or I need to watch out for?

 

[Barnes_de]

*.txt and *.dat-files are attached here:

 

[sar104]

It looks like a battery disconnect or FC failure - there is nothing unusual in either of the logs before the disconnect. It hit some strong winds just before the problem occurred.



If it did fail in mid-air, then applying a standard drag model with the estimated wind conditions (9 m/s out of the NE) at the flight altitude, suggests that it should have come down at the location shown below:

 

[Barnes_de]

@sar104: Thank you. I was out today and had no luck at the estimated crash location within 20m radius.

What can cause the battery to disconnect other than I did not properly snap it in?

I am also wondering if at full forward speed a sudden high velocity front wind can cause the mavic to crash in that way that the nose dives the tail goes up, so that the uplift is insufficient causing the Mavic 2 Pro to unwanted loose height quick?

Provided I find the drone, may it store additional data?

 

[sar104]

@sar104: Thank you. I was out today and had no luck at the estimated crash location within 20m radius.

What can cause the battery to disconnect other than I did not properly snap it in?

I am also wondering if at full forward speed a sudden high velocity front wind can cause the mavic to crash in that way that the nose dives the tail goes up, so that the uplift is insufficient causing the Mavic 2 Pro to unwanted loose height quick?

Provided I find the drone, may it store additional data?

The battery disconnect is caused by not fully engaging the clips. That's only one possible explanation though. Failure of the FC is another that has been seen with the M2. The disconnect obviously leads to an immediate plummet to earth. The FC issue is a bit less certain but in the cases I've seen so far the effect has been the same. The sudden disconnect is very indicative of a catastrophic failure, so I'm a little surprised that you didn't find it - how confident are you that you would have found it if it were at that location?

Wind gusts should not be able to crash the aircraft. There will be a DAT file on the aircraft, but unlike earlier models, M2 DAT files are only readable by DJI.

 

[mikeyway]

@sar104: Thank you. I was out today and had no luck at the estimated crash location within 20m radius.

What can cause the battery to disconnect other than I did not properly snap it in?

I am also wondering if at full forward speed a sudden high velocity front wind can cause the mavic to crash in that way that the nose dives the tail goes up, so that the uplift is insufficient causing the Mavic 2 Pro to unwanted loose height quick?

Provided I find the drone, may it store additional data?

When looking at the data everything seems fine, the motors are spinning normally and there are no signal/gps errors.
The only thin I can see that "OA:vertLowLimit" is set to true from 3 to 7 sec after takeoff.
If it wasn't found at the location specified above, then either it must have flown off in the same direction (which is unlikely) or it fell perfectly between 2 bushes.
If you recover the MP 2 we can see all the logs after the feed cut off, especially how the FC reacted when the connection was lost. If there are no more information on the drone we can assume the battery got disconnected.

 

[sar104]

When looking at the data everything seems fine, the motors are spinning normally and there are no signal/gps errors.
The only thin I can see that "OA:vertLowLimit" is set to true from 3 to 7 sec after takeoff.
If it wasn't found at the location specified above, then either it must have flown off in the same direction (which is unlikely) or it fell perfectly between 2 bushes.
If you recover the MP 2 we can see all the logs after the feed cut off, especially how the FC reacted when the connection was lost. If there are no more information on the drone we can assume the battery got disconnected.

Actually the aircraft logs won't be of any help - only DJI can read those.

 

[Barnes_de]

GOOD NEWS: Susi is back after 3 weeks :-D

I reached out to “sar104” to extrapolate the flight path last Thursday. And, in return he asked me about the vegetation at the last known location of my M2P. So I went to make a pic the next morning:

When intended to leave the sight, the farmer had me the good news: he found Susi while fertilizing the field with his tractor.
The location was “in the center of the field right where I marked it.” (Note: Earlier during my search I handed him a print of the last known location and the the suspect location of sar104.) The battery was separated about 7m away.

Why I did not find it remains a big “?”.

Susi is in bad shape:

Today, I called DJI Care Refresh...

 

[sar104]

That's good - at least you get to use Refresh now. I'm glad that I persuaded you that it had to be there.

 

[razoraerial]

That's good - at least you get to use Refresh now. I'm glad that I persuaded you that it had to be there.

@sar104 . Nice job. You the man. I hope like crazy. I never need your specific services. Lol

Glad you got susi back.

 

[Barnes_de]

New Susi::

incl. high visibility & recovery devices

 

[Deleted member 94047]

Congratulations OP, a real happy ending

The battery was separated about 7m away.

So the battery separated from the aircraft while in flight?

 

[Meta4]

So the battery separated from the aircraft while in flight?

Maybe ... but probably not.
It's common for batteries to become dislodged in a crash.

 

[Deleted member 94047]

The found 7 meters away kinda indicates a mid air separation, don't you think?

 

[WithTheBirds]

The found 7 meters away kinda indicates a mid air separation, don't you think?

Not necessarily- looking at the battery photo shifts the balance perhaps. The battery looks, from what appears to be direct impact damage, like if came in hard and independent of the drone.

I would like to hope the battery came out in the air. It’s a more comforting thought than the prospect that yeh flight controllers might be throwing a leg out of bed.

 

[Deleted member 94047]

Yeah, looking at the picture again, it doesn't look like the battery just fell out of the sky.

OP: Did you recover the video before the crash?

 

[Barnes_de]

There was no video taken, unfortunately.

To prevent mistakes, I asked DJI if they would look into the data of the crashed Mavic 2 . The service replied that they do not do so with Care Refresh Express.

Thus, it remains likely but uncertain that the batterie did not clip 100%.

The deformation damage of the batterie could also be caused from the tractor running over it.

 

[Meta4]

The found 7 meters away kinda indicates a mid air separation, don't you think?

Not definitely.
It fell from 51 metres - that's quite an impact.

 

[Lukea777]

Hallo!

Unluckily, my first post in this forum is: my “Susi” (Mavic 2 Pro) is lost.

I was twice flying the drone on April 10th and had no problems on flight number 1. The battery was changed for a direct second take-off. 2 min into the second flight, I had a sudden signal loss (Camera and Controller) at a straight flight:

• see next Posts for *.txt and *.dat-files
• Unfortunately, there is no video.

First, I expected a return to home and kept calm. The RTH altitude setting was at 40m and no obstacle is higher than ~20m. After 10 minutes I went to the last known location and searched for about 2 hours. The plants on the surrounding fields were <25cm high. I also spoke to the farmer who was very gentle, and I left my contact details. Eventually, I gave up and the drone is lost.

Other considerations:

• The evening before I updated all devices to the latest firmware.
• The weather was fine.
• The signal loss appeared when I was looking down on the Smart Controller just when I intended to fly the drone on a right U-turn to bring it back closer.

The same day of the loss I contacted DJI. In the meantime, the technicians couldn't see the cause of the accident from the information from the provided log files. Their support offered a discount on a new purchase.

Thus, the only potential explanations I have from reading in this forum is that

1. the battery may have disconnected in flight. But then the drone should be close to the last known location. Or:
2. the drone had a flyaway with a fresh batterie.

I would really appreciate somes’ help: What might be the root cause and where could I search for Susi?

Also, to prevent it to happen again, I am planning the next drone to get a visible skin (neon orange or so) and a tracker (Loc8tor) and acoustic signal device (DroneKeeper micro). Are there other things you recommend or I need to watch out for?

Hi, I have recently had a near identical flyaway. I am also leaning towards an FC failure. DJI has offered a discount but there is more in the .DAT file that others have found. I am still awaiting DJI to complete their second look into the files (specifically the .DAT)

I am finding it disturbing that there are so many of these near identical circumstances.

 

[sar104]

Hi, I have recently had a near identical flyaway. I am also leaning towards an FC failure. DJI has offered a discount but there is more in the .DAT file that others have found. I am still awaiting DJI to complete their second look into the files (specifically the .DAT)

I am finding it disturbing that there are so many of these near identical circumstances.

In the cases I've looked at where the DAT file showed clear signs of FC failure, DJI has replaced the aircraft, even when it wasn't recovered. What, exactly, does the DAT file show?

EDIT: OK - I just saw your other thread.