Mavic 3 Cine fell from the sky after ESC Error

[Danymite]

Hello all, my Mavic 3 Cine crashed yesterday above water while I was on a shooting. I got an ESC Error message and the drone started flipping and crashed on the water.

I opened a Flyaway report with DJI and they replied that the crash was due to pilot error. Here's their reply:

"1. The aircraft worked under Sport mode;
2. Flight Time T=12:43, Relative Height H=5.4 m, Distance to Home Point D=192.3 m, the pilot pushed forward the pitch stick and pulled down the throttle stick, then the aircraft crashed when flying forward at 3.2m/s while descending at 0.9m/s;

Conclusion: The incident was caused by the operation error of the pilot. The aircraft could not avoid obstacles and its braking distance increased significantly in Sport mode. Please fly with caution and do not fly too close to the surface of the water."

I have DJI Care Refresh but I'm almost sure this was an equipment failure, despite DJI report.

Here's the link with the flight log. If any of you guys, with much more expertise analysing flight data, could help me clarify this incident before I reply to DJI, I would really appreciate it.

DJI Flight Log Viewer - PhantomHelp.com

Thanks

 

[Phantomrain.org]

I think two things happened here :

The Esc error over the water while the drone is trying to maintain position over the water is normal as it battling the wind to maintain . Nothing more than a warning but might have caused you to panic .

I also think that when you slowed down to around 2 mph and at 17 ft and than took off again over the water , the drone dropped a few more feet and you accidentally flew it into the water.

Sport mode over the water at 17 ft is tricky at 600 ft

With that said: This is the part of the Equation that does not add up : Lets see what the experts say.

" The drone started flipping and crashed on the water.

Phantomrain.org
Gear to fly in the Rain,

 

[Yorkshire_Pud]

What log or logs did you send them? This one? Any others including DATs from the phone?
Did you recover the drone? If not, simple care refresh is of no use ....since you have no drone to return.
That I can see, from 12:43 onwards, you
a) partially closed the throttle for around 0.6s sec &
b) gave it partial forward stick for around 0.4sec.

I would wait and see what @slup, @sar104 or @Meta4 say but what I see at a glance does not look like pilot error.
Well it looks as if I was up a Gumtree, brilliant @slup. So the next sentence is not needed.

If folks, including the above, agree I would post this on the DJI forum and ask them to reconsider, the Mods there can sometimes seemingly 'kick things upstairs'.

Also, if others agree that this is equipment failure then surely it is a warranty claim and neither a care refresh claim nor a flyaway claim?

 

[Starz]

Was there a particular reason for the use of sport mode?

 

[slup]

Well... the TXT log isn't exactly the correct one to find out the actual root cause (if one can be found) for the ESC error. But in this case I bet the reason was water with following electronic shortage.

This "joy"-flight was conducted out over the sea with a HP right on the water edge, so heights that's reported in the log is relative HP but also the water surface (without possible waves that said).

This was the place... it was a bit windy, the drone was affected by wind speeds between 5-9m/ according to the log. Wouldn't surprise me if the waves during the flight were pretty similar to what's seen in the Google Earth picture here below.


Have red circled the very last leg this drone made... the chart below cover this also. (Please note the, for the case, suitable wave that happens to be right were the flight path ends...)



If starting to follow the stick inputs, speeds (dark green), heights (red) (sadly only barometric, VPS didn't worked properly over the water) & the telemetry data (light green, magenta & black) from 763,5sec (where the drone is depicted in above sat.pic.) to the end of the log.

At 763,5sec you starts to let off a positive elevator input (blue dashed) & at the same time starts to apply a slight input on the throttle (purple dashed) for a descent (stick value 1024= neutral stick). The barometric height was reporting 17,7ft at this point (... and we know that the barometric height can be off like +/-10ft especially after high speed flights).

Jumping forward 0,6sec to 764,1sec the drone abruptly pitch down to -37 degrees & very soon after roll over to 173 degrees (mainly up side down). The yaw axis is quite unaffected during all this... it turns a couple 10th of degrees first CCW then back CW. And the flight is over.

My firm belief is that your drone hit a wave knocking it front down all over upside down before it was swallowed by the sea. You mainly flew to low, didn't factor in the slight inaccuracy a barometric sensor can have & forgot the waves.

The other that could have caused your drone to dive is a failing prop or possibly a motor in either of the 4 corners... but that's unlikely when looking at the yaw axis. If one corner fails the drone starts to spin, either CCW or CW depending on which corner that fails... but we can't see that in your log, instead it "twitch", first slightly CCW then back CW.

Out from the data available I say this was a plain pilot error, flying to low & hitting a wave that flipped the drone over & the water ingress then caused the ESC errors before the log ended.

 

[Meta4]

I have DJI Care Refresh but I'm almost sure this was an equipment failure, despite DJI report.

The equipment was not the problem.
The ESC error messages only showed as the drone hit the water and are symptoms of the crash, not the cause.

You were flying in Sport Mode, 195 metres out from the launch point.
How well could you see the drone at that distance to judge how high it was above the water?

Because you were in Sport Mode, the VPS wasn't able to give an accurate indication of the actual height above the water.
The height shown on screen from barometric sensor commonly drifts 3-6 metres over the duration of a flight and cannot be relied on for accurate distance above the water after flying for some time.
Another factor to beware of is that the wideangle lens of the drone gives a false impression of the distance to the water as it makes everything look further away than it actually is.

Flying low to the water in sport mode is risky, more so if you cannot see the drone and are relying on the screen view.
Waves can create another hazard with the water level falling and rising under the drone.

The last second of the recorded data tells the story.
You were flying low above the water, but as explained above we can't tell from the data, the distance above the water.

At 12:43.7 you pulled the left stick down gently for 0.6 seconds.
This brought the drone down closer, by about 0.3 metres.
At 12:43.1, while you still had the left stick down and were descending, the data shows the drone catching the water surface, tipping downwards and rolling over.
This is the time that the first ESC warning shows, no doubt caused by the ingress of salt water.

Flying close to the water's surface should only be done when you can clearly see how high the drone is above the water.

 

[Yorkshire_Pud]

Brilliant detective work @slup @Meta4

 

[TonyPHX]

This seems like a deja vu post from the manufacturers forum. Seems like the best advise to the pilot has been given there and here.

Correction, I confused this with another post. Seems like a lot of dips into the water lately.

In any event, good luck @Danymite getting back int the air soon!

 

[Danymite]

Thanks a lot guys for all your help and support, especially @Meta4 and @slup for the detailed report.

Have a nice weekend and safe flights.