Drone crash reason unknown & upward sensor damaged?

[kem]

Hello Everybody,

I encountered a strange crash 2 times with 2 different M2 pro.

I took off in low light conditions (but not fully dark) close to a building (5m).
The drone was hoovering (at 2m) and started to slowly fly backwards. It did not react to any order. Before it crashed into the bulding I managed to lower the alt, so it survived the crash with small scratches.

This drone was replaced due to factory dead SD card reader.

I got a new one, I did the same thing what I described above, in addition I calibrated the compass (had to try many times due to magnetic interf).
This time it was closer to the wall(2-3m) an was flying higher (at 2.5m) and I did not manage to bring it down.

Looks like the upward sensor suffered a damage. I tried to fly again in good light conditions, I managed to ascend up to 25-30 meters, and the drone reported upward obstacle on the clear sky. I tried a few times, but it did not get any better. At the last try the drone simply started to fly away very fast. I immediately switched it to sport mode. Looks like it helped. I could maually land.

I need your help to understand
- why it crashed into the wall
- what to do with the sensor (if replacement possible?)
- why did it start to drift away with damaged sensor
- whether switching to sport mode cab stop uncontrollable drone

By the way, there is no visible damage on the upward sensor. I will try to recalibrate in the mean time.

I have a 3rd party insurance, but I do not want to trigger it yet.

Thank you very much!

Br,
Istvan

 

[Meta4]

I got a new one, I did the same thing what I described above, in addition I calibrated the compass (had to try many times due to magnetic interf).

That should have been an alarm bell for you.
The compass was warning you of a magnetic problem nearby (and probably an unsuitable launch point).
Recalibrating the compass won't fix that problem.

I need your help to understand
- why it crashed into the wall
- why did it start to drift away with damaged sensor
- whether switching to sport mode cab stop uncontrollable drone

There a few possibe explanations but to find out which we would need to see your recorded flight data.
Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report of the flight.
Come back and post a link to the report it gives you.

 

[kilomikebravo]

That should have been an alarm bell for you.

Yes indeed and could have prevented the crash.

 

[crlmjohnson]

sounds like a compass error or magnetic interfere

 

[kem]

Hello Guys,

Indeed, was most provably the compass. I calibrated everything again, the top sensor is working again!

From now on I am not gonna take off when strong magnetic interference is present at the home point. I am going to check all the sensor state as well before taking off.

By the way I used Drone Data Management and Flight Analysis | Airdata UAV to check the flight logs.

 

[kilomikebravo]

From now on I am not gonna take off when strong magnetic interference is present at the home point.

kem: Now if only others would see the light, we might not have as many lost drones.