Mavic crashed into office building...what did I do wrong?

esm123 · May 6, 2017

Hi all,
I had a perfect mavic, never had a single issue for months...Did the latest software upgrade.. calibrated compass, re-did all the settings... took off vertically about 150 feet, drone went completely haywire and crashed into an office building. (Drone is totally destroyed) - I tried to control it while it was going crazy, it would react to my input but I couldn't keep up with it's movements and it was going way too fast.

I sent the mavic to DJI for repair.. but I'd like to check the flight recorder data to see what happened...
I have the SD card, and the app on my phone with all the data. What can I upload for you experts to help me analyze what happened?
thank you

Kilrah · May 6, 2017

You should have gotten the flight log form the aircraft before sending it, the important data usually needed to explain erratic flight behavior is not present in the phone log.

Apart from that, never recalibrate compass just for the sake of it. Do it in an inappropriate place and you get just that.

esm123 · May 6, 2017

Did not know that the aircraft kept data outside of the memory card. That sucks.
The app asked me to re-calibrate compass before I took off. The last place I flew it was outside of the country.

Robbyg · May 6, 2017

If you take compass into an area with a lot of metal it will read incorrectly. That is why a properly calibrated Mavic will say it needs calibration when you carry into an area full of metal objects. When you calibrate it in this bad location the mavic will think it is properly calibrated but once you get it up in the air and far from all the metal the Mavic will suddenly be out of calibration and will behave erratically.

You always need to calibrate in a open location away from any buildings and metal. Once that is done ignore any calibration warnings that occur when your near building and metal. I have only calibrated my Mavic 3 times in 5 months.

Rob

esm123 · May 6, 2017

Gotcha. I usually only calibrate when I travel to new locations and fly. It always prompts me to. This time I flew in Peru and came back to Atlanta. Updated the software and it prompted me to calibrate once I turned on the drone outside. I was near buildings but not too close. What is a good proximity?
From reading the log on the phone:
The drone started moving and spinning on its own. Then the visual system turned off on its own. Then I hear ATTI mode in the video... then the drone hit the building and crashed. Doesn't seem like a compass issue...but I'm not sure.

esm123 · May 6, 2017

the first warning was "altitude too large. Exit obstacle sensing" I've never seen that before. That error message came a few seconds after the drone started spinning and moving on its own.

Robbyg · May 6, 2017

esm123 said:
the first warning was "altitude too large. Exit obstacle sensing" I've never seen that before. That error message came a few seconds after the drone started spinning and moving on its own.

Can you upload the Logs?

Rob

esm123 · May 6, 2017

FLY110.DAT@17-04-29_07-54-32-592

Thanks!

Robbyg · May 6, 2017

esm123
I invited Budwalker and Cyberpower to also take a look.
One of us should be getting back to you soon

Rob

BudWalker · May 6, 2017

esm123 said:
FLY110.DAT@17-04-29_07-54-32-592

Thanks!

That .DAT didn't come from the Mavic itself and won't give us the info we need. From your description it sounds like you may have launched from a geomagnetically distorted location. The .txt from the DJI Go App on the tablet would help confirm this if you can retrieve it. You can find info on retrieving it here
https://www.phantomhelp.com/LogViewer/upload/
Either upload it to that site and provide the link it gives you
Or, you can attach it directly to a post here since it is a .txt

esm123 · May 6, 2017

Yeah I sent in the mavic for repair but I have the SD card. I've attached the latest txt file. Help me understand how my description seemed like a geomagnetically distorted location? Is it because I had to calibrate the compass? Or just from the erratic behavior or the mavic? Thank you all for your help. I want to understand if it was my fault, and what I can do to make sure it doesn't happen again. I've taken a lot of precaution making sure I don't crash my mavic and it feels awful losing one!

DJIFlightRecord_2017-04-29_[19-56-53].txt

msinger · May 6, 2017

Here's the uploaded log:
Phantom Log Viewer - PhantomHelp.com

msinger · May 6, 2017

Did you take off from concrete? Is that where you calibrated the compass too?

esm123 · May 6, 2017

Seems to me like there was a gps issue.. maybe some kind of reflection bouncing off the buildings? But I still don't understand why the drone would start turning around and moving on its own. The speeds are insane 24 mph without input

Robbyg · May 6, 2017

From the map I see, something that is interesting. The exact moment the craft started to move without input from esm123 it seemed to be exactly perpendicular to a power line and the transformer.

Also that high rise building 150ft away is another interesting facet, especially the Helicopter pad on top of it, along with the three other pads a little further away. I wonder if some kind of anti drone tech was used. (Doubt it but..)

Rob

msinger · May 6, 2017

esm123 said:
Seems to me like there was a gps issue

What kind of GPS issue would cause erratic flight? I've never heard of such a thing.

esm123 · May 6, 2017

msinger said:
Did you take off from concrete? Is that where you calibrated the compass too?

I guess you can call it that? It's above a pool floor..? I calibrated it by picking it up mid air and turning it around..until I got the green lights. It flew just fine the first few 15 seconds or so

esm123 · May 6, 2017

msinger said:
What kind of GPS issue would cause erratic flight? I've never heard of such a thing.

Me either..just reading from the error logs. Seems to be the only thing that started it. Gps mismatch.

Robbyg · May 6, 2017

msinger said:
What kind of GPS issue would cause erratic flight? I've never heard of such a thing.

He's got a ton of errors

1) GPS Position No Match

2)Attitude too Large. Exit Forward Obstacle Sensing

3)Current RTH route will pass a No-Fly zone.

4)Motor Current Error

I really wish we had the DAT file for this one.

Rob

msinger · May 6, 2017

Robbyg said:
He's got a ton of errors

Yes, sir. Making impact with a large building tends to log lots of errors. If you look closely at the log, you'll see only the "GPS Position NoMatch" messages appear prior to impact. I've seen those errors pop during flights where nothing unusual seemed to occur mid-flight.