Recovered crashed MA, cause of crash unknown

[Bryan D]

Hello all,

My dad's MA crashed yesterday while flying above a forest at ca. 30 meters altitude. We were fortunate enough to recover it with what seems like minimum damage (few scratches, one of the rear landing pad gone).

I am trying to understand what went wrong before we fly again. I suspect a tree impact but my very untrained eyes were unable to confirm that by lookking at the flight data. I have extracted the flight data enclosed from the phone and visualised them using CSView thanks to SAR's invaluable resources. However I am unable to confirm the cause of the crash...

Could a kind soul help looking at the data?

Many thanks

 

[boblui]

75 seconds into the flight the signal was sharply cut off at this point ( marked by the star )



About half an hour later the craft was picked up at the end of the flight path. The craft was still powered on.

I think the signal was just blocked by the trees but if the settings were right, it should have returned to the home point by itself. May be it hit a tree taller than 30 meters before initiating RTH ? How high are the trees around the location where the craft was found ?

 

[Bryan D]

Thanks for taking a look!

So, most trees are under 30 m, but going back on-site with my MA 2 I noticed a few around the 35 m mark. So he could have hit on of these, but it’s really just a few random tops...

I also think it hit a tree before RTH, I would just like to find confirmation in the data. Ideally I would like to see weird acceleration, pitch, yaw or roll data just before the loss of contact with the RC (indicating a possible collision) but I cannot seem to find that. It looks to me like everything is okay before the loss of signal.
Any idea?

 

[boblui]

It looks to me like everything is okay before the loss of signal.
Any idea?

Yes, the craft was flying OK before the signal cut off.

 

[Bryan D]

Thank you. So that would mean the crash happened after cut off, which is surprising since it should have been RTH using vision system to avoid obstacles, right? Also, there is no record of fail safe RTH to be activated. I can however confirm the drone is set up to RTH in case of signal loss.

 

[boblui]

After the downlink was broken the craft continued to fly for 90 ~ 100 meters before it crashed. May be the uplink was still working so RTH has never been initiated ?

 

[Bryan D]

Thanks! Just to clarify: downlink is the video signal and uplink is the “RC commands”?

 

[boblui]

Thanks! Just to clarify: downlink is the video signal and uplink is the “RC commands”?

downlink is live video feed + telemetry data ( flight log data in the phone ) and uplink is the RC commands.

 

[Bryan D]

Thanks. I guess that could explain what happened since it did not seem he had his eyes on the screen when the downlink broke (he was flaying backwards...). So the RC data available in the flight data is only the downlink data (i.e. no way to verify the difference between downlink and uplink cut off)?

 

[boblui]

no way to verify the difference between downlink and uplink cut off ?

Actually it is possible because there are flight log in the drone as well. Unfortunately only DJI knows how to read those flight log data.

 

[Meta4]

Could a kind soul help looking at the data?

Yes ... if you could post the .txt file.

 

[Bryan D]

Yes ... if you could post the .txt file.

Isn’t what I posted enough?

 

[Meta4]

Isn’t what I posted enough?

I don't do .dat files, but I do read .txt files and the .txt file will have everything needed to look into the incident.

 

[Bryan D]

Hmm okay, any idea how to convert?

 

[Meta4]

Hmm okay, any idea how to convert?

No conversion necessary.
If it won't attach here, just put it in dropbox or similar and post a link.

 

[Lets Fly]

But it’s really just a few random tops.
Thats all it takes.