Mavic Crashed into a River

Robbyg · Jun 27, 2017

Selous Scout said:
I'm guessing I was ~6 feet up before the final decent with no forward motion.

Any luck with a YouTube upload? It will settle many of the questions.

Rob

Selous Scout · Jun 27, 2017

Robbyg said:
Any luck with a YouTube upload? It will settle many of the questions.

Rob

I will when I get home.

Selous Scout · Jun 27, 2017

I have uploaded the flight to Youtube.

I also uploaded a video of the playback on the DJI Go 4 app.

So, now everybody knows where a crashed Mavic is. Sort of. Who knows how far it tumbled down river. I will attempt a recovery this weekend. I think DJI has made up their mind that it is my fault. Maybe it was but I still think I didn't cause the crash. What do you guys think? Do I take the blame for this one?

Robbyg · Jun 27, 2017

Well it's not an uphill sort of problem since you actually turned around just before it descended.
Its hard to tell how high up you are but it looks like about 3 feet.
I am going to try and sync the video with the Data and see if I can find out some more info.

Rob

Jeff7577 · Jun 27, 2017

I think the VPS put your Mavic in the water but even then DJI is right, its not a malfunction.

Selous Scout · Jun 27, 2017

Jeff7577 said:
I think the VPS put your Mavic in the water but even then DJI is right, its not a malfunction.

I thought about that too. I didn't completely disable VPS but landing protection was off since I hand launched and intended to hand catch it.

Cut.Aussie · Jun 28, 2017

Look carefully at the white water in the last few seconds of flight, the bubbles are getting larger and clearer, your flying lower and lower. Sorry but I think that's pilot error.

BudWalker · Jun 28, 2017

Selous Scout said:
I have uploaded the flight to Youtube.

I also uploaded a video of the playback on the DJI Go 4 app.

So, now everybody knows where a crashed Mavic is. Sort of. Who knows how far it tumbled down river. I will attempt a recovery this weekend. I think DJI has made up their mind that it is my fault. Maybe it was but I still think I didn't cause the crash. What do you guys think? Do I take the blame for this one?

The video pretty much matches the data in the .txt. The video and .txt data negates some of the theories expressed here, including one of my own (It wasn't the elevator input at the very end that caused the sinking).

At about 987 negative rudder was input and then at 988 the Mavic yawed 28 degrees CCW. Coincident with the rudder input the Mavic began to sink and continued sinking after the rudder input was removed. The Mavic hit the water at about 991.

From the video it's hard to tell if the vps data is correct. I.e. was it really 3.6 meters above the surface when the rudder input occurred. If the data is incorrect it's just a scaling error. But, it hardly matters; the sinking started with the rudder input.

One thing I just noticed is that the flyCState was Cinematic during this interval. Don't know what that means or if it's effects are material. But, I've not seen this before.

Lake_Flyer · Jun 28, 2017

Did you keep the mavic in clear line of site? I noticed you made a left turn following the river bend and you got a lot of trees between you and the bird. Anything can happen when you have no clear visual line of site. The controller signals are getting inaccurate and before link is failing completely (and it kicks into RTH, which is not something you want to happen in such a location) strange things are bound to happen.

But I could be wrong and it might be that you had a perfect free line to the mavic, it just seems otherwise in the video.

Lake_Flyer · Jun 28, 2017

BudWalker said:
One thing I just noticed is that the flyCState was Cinematic during this interval. Don't know what that means or if it's effects are material. But, I've not seen this before.

Well, for one thing, in Cinematic all controls are dead slow. And it kind of behaves like in Atti with no wind.

Lake_Flyer · Jun 28, 2017

Lake_Flyer said:
Well, for one thing, in Cinematic all controls are dead slow. And it kind of behaves like in Atti with no wind.

However it stops and turns quite suddenly, un-cinematic like. It looks indeed an autolanding invoked by VPS, upstream the surface came closer and closer. VPS hates water and fast running water might even be worse.

BudWalker · Jun 28, 2017

Lake_Flyer said:
However it stops and turns quite suddenly, un-cinematic like. It looks indeed an autolanding invoked by VPS, upstream the surface came closer and closer. VPS hates water and fast running water might even be worse.

Why would vps invoke an autolanding? Vps is just a sensor. Further, it's value hadn't changed when the sinking or autolanding started.

msinger · Jun 28, 2017

Lake_Flyer said:
But, I've not seen this before.

Me neither.

Selous Scout · Jun 28, 2017

Lake_Flyer said:
Did you keep the mavic in clear line of site? I noticed you made a left turn following the river bend and you got a lot of trees between you and the bird. Anything can happen when you have no clear visual line of site. The controller signals are getting inaccurate and before link is failing completely (and it kicks into RTH, which is not something you want to happen in such a location) strange things are bound to happen.

But I could be wrong and it might be that you had a perfect free line to the mavic, it just seems otherwise in the video.

The Mavic was probably just outside of LOS when I stopped and started the left turn to return home. I was looking at my iPhone screen and not the Mavic for this portion of the flight.

Selous Scout · Jun 28, 2017

BudWalker said:
The video pretty much matches the data in the .txt. The video and .txt data negates some of the theories expressed here, including one of my own (It wasn't the elevator input at the very end that caused the sinking).

At about 987 negative rudder was input and then at 988 the Mavic yawed 28 degrees CCW. Coincident with the rudder input the Mavic began to sink and continued sinking after the rudder input was removed. The Mavic hit the water at about 991.
View attachment 16005

From the video it's hard to tell if the vps data is correct. I.e. was it really 3.6 meters above the surface when the rudder input occurred. If the data is incorrect it's just a scaling error. But, it hardly matters; the sinking started with the rudder input.

One thing I just noticed is that the flyCState was Cinematic during this interval. Don't know what that means or if it's effects are material. But, I've not seen this before.

Thanks for taking the time to look at the data. I did turn off landing protection but I don't know if that changes with the Cinematic flight mode.