Mavic 2 Pro flew upward sensors did not stop and hit branches

drekko · May 7, 2021

Hi
My M2P crashed when I was doing active track. The battery was low and it attempted to fly up to go to its go home height. But over hanging tree branches were in the way above it. The drone still tried to go up. Hit a branch, then flew down then kept trying again to go up. Hitting branches again
This happened before I could cancel the go home unfortunately

Anyway my drone is with DJI and I have given the the following flight logs to analyze to see if it was a done error that caused this or my fault

Can anyone help pick apart what happened here from the logs and from what I have explained?

I have attached the crash video and flight log and here is a link to the crash video:

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Phantomrain.org · May 7, 2021

The battery was low and the RTH did exactly what it was designed to do,
Over ride and start the Return to Home Procedure.

Its Pilot error on several levels , Remember you can always cancel return to home and take over the drone but you have to have quick access to the controller .

Phantomrain.org
Gear to fly your Mavic in the RAIN an LAND on the Waves.

slup · May 7, 2021

Wow ... flying with active track under that tree roof is like begging for a crash. This is nothing else than a pilot error.

Just reading out from the manual regarding the upward OD sensors ...

drekko · May 7, 2021

slup said:
Wow ... flying with active track under that tree roof is like begging for a crash. This is nothing else than a pilot error.

View attachment 128789

Just reading out from the manual regarding the upward OD sensors ...

View attachment 128790

I didn't show you the first 15 mins of the video. It followed me autonomously for about 2km dodging trees and following me. The only reason it crashed is because it started to fly home. Flying up and hitting branches going up

Thanks I for the info about the upward sensor. I thought it was like the other sensors

slup · May 7, 2021

The log included the whole flight ... so I saw it. Plain & simple, you were lucky the whole time before the crash ... now it was the low battery RTH that triggered the ascend ... but you clearly relayed too much on the OD sensors in this flight & didn't know enough about their limitations. Furthermore you didn't take the low battery RTH scenario into consideration at all.

In below chart you in the green graph see the 10sec countdown before the RTH kicked in ... the blue graph shows that the low battery RTH level was 28% just there & when your battery reached below that (red graph 27%) it executed RTH (Brownish background color).

Would be a huge surprise if DJI take any responsibility in this case.

Flycaster · May 7, 2021

That's really sucky to happen, but DJI doesn't "play well" with thin branches/wires...

drekko · May 7, 2021

Flycaster said:
That's really sucky to happen, but DJI doesn't "play well" with thin branches/wires...

Yeh. Oh well lessoned learned for next time I use active track

drekko · May 7, 2021

slup said:
The log included the whole flight ... so I saw it. Plain & simple, you were lucky the whole time before the crash ... now it was the low battery RTH that triggered the ascend ... but you clearly relayed too much on the OD sensors in this flight & didn't know enough about their limitations. Furthermore you didn't take the low battery RTH scenario into consideration at all.

In below chart you in the green graph see the 10sec countdown before the RTH kicked in ... the blue graph shows that the low battery RTH level was 28% just there & when your battery reached below that (red graph 27%) it executed RTH (Brownish background color).

Would be a huge surprise if DJI take any responsibility in this case.

View attachment 128791

My reply was in response for when you said "Wow ... flying with active track under that tree roof is like begging for a crash. This is nothing else than a pilot error."

The flying through tree branches roof was not the cause of the crash and I don't believe I was "lucky" in avoiding this as I have used active track with APAS turned on a few times before in this area of trees and the drone does really well with dodging obstacles. As long as the obstacles have some gaps for the drone to work out where to go through.
Which in this flight it did great, and you can only see from the full video not the logs

The cause of the crash was the RTH ascending which was my fault. Next time ill know not to over estimate the upward sensors ( I actually thought they where like the forward sensors but they are just infrared)

I did take low battery RTH scenario into consideration. What I didnt know is the upward sensors are not as reliable as the front and back. I thought the drone would stop and I would have time to cancel RTH but I was wrong on that

Camino Ken · May 7, 2021

I have done some semi-scientific tests of the obstacle avoidance sensors in my M2P and found that the front and rear sensors cannot reliably detect anything smaller than 1 in (2.5cm) in diameter. The top and side sensors are worse. iMHO you were flirting with disaster the whole flight.

360 Guy · May 7, 2021

I try to avoid trees like the plague and you fly amongst them.............geeeeeez.......enough said.

bigswifty · Jun 3, 2021

I am constantly amazed at what people think these drones will do. I guess I'm a timid, perhaps overly conservative operator, but I wouldn't have undertaken that flight in a million years.