Ok on vacation, set up my mavic pro settings, did pre flight check at hotel, imu compus good .. check... I check it again at location and appear good.  I fly my drone a couple times and the last time it does not end well.  I get a stick error on my drone controller that I don't immediatly see, and it starts to fly away.. at this point I don't start to panic yet... but it's my first time flying from a boat over the ocean... seeing how this story end yet?  
I press the pause button, but I have no stick control, if I remember my screen disconnected... using Samsung notepad.  I check the wires plug and un plug nothing.. can feel panic start to happen as to me it seems like it is flying away again.  I pause the magic again, start saying no no no no.. that does not seem to help.  I am trying to clear my landing zone on boat, but photographer was flirting with girl on boat and I can't bet him to move because I don't think he can understand English well enough.  He just waves at me and where he thinks drone is.
Other guy from boat jumps in ocean.  I get mavic about 4 feet above ocean but it just hovers now. He has his hand up wanting to catch it but i dont want hjm to because im afraid of possible damage to his hand.
I yell at photographer to move and pull him he moves, screen still has greyed out last image on it.  I rip out cord and remove tab.et from controller and now see the controller is saying something about centering jou sticks.  I am afraid to press rth because afraid of fly away and no stick control.  Think of powering down remote but will mavic, fly away again if I turn off remote, or chop up really nice guy wanting to help to catch mavic. Now good amount of panic... keep trying to lower mavic but no control... I center joysticks a few times... finally very slow, unresponsive but a bit of control back.  Slowly raid mavic over rail and to landing spot.  Starting to land... oh no going towards rail.. try to correct, controller still ...ty?.. wrap wrap wrap blades hit rail from inside the boat, this pulls mavic over the edge and splash... salt water bath.  I'm on vacation no tools, nothing here really in domician...
He dives gets drone for me, I immediately remove battery, use fresh water shower to try to flush salt water off and out of drone, but with no tools pretty $&@(#(%* up.  Blow out drone with dive tanks and hope for best when home I  three days when I can disassemble it.  
So beyond logistics of keeping my landing place more clear... what happened

https://www.phantomhelp.com/LogViewer/ZSFTWLNFU39JVB86G0WX/

Looking at other site air data have, I got a massive amount of signal errors and no understanding why... needless to say... Very crappy ending to an otherwise very good day https://app.airdata.com/flight/8617c2392c9a28435990ed2d54a2af8d/SENSORS

Please forgive typing errors as in hotel on tablet...

Never fly that drone again, the conductivity of the sea water will ensure the circuitry is damaged, within milliseconds.

Very sorry to hear that! It would be good to analyse logs to see what went wrong.

I know its not always avoidable nor a guarantee the drone survives a fall but but I try and limit flying over water when I can.

*DM* Posted at 5-3 23:55
Very sorry to hear that! It would be good to analyse logs to see what went wrong.

I know its not always avoidable nor a guarantee the drone survives a fall but but I try and limit flying over water when I can.

The way I see it, if mine crashes over water it's a good excuse to upgrade

But in all seriousness sounds pretty unfortunate. I've often had stick errors but that's pre takeoff and I just re-calibrate before taking off and it is all fine then. Not sure when the last time you calibrated your controls were but maybe that could be part of it..?

*DM* Posted at 5-3 23:55
Very sorry to hear that! It would be good to analyse logs to see what went wrong.

I know its not always avoidable nor a guarantee the drone survives a fall but but I try and limit flying over water when I can.[Image]

Hello DM I included two links to the logs at the bottom of the story if you want to view.  I am wondering what coukd of caused the lack of control and stick errors.  

4U2NVME Posted at 5-4 04:37
Hello DM I included two links to the logs at the bottom of the story if you want to view.  I am wondering what coukd of caused the lack of control and stick errors.

I'm sorry to read of your loss. Looking at your phantom help log the flight was flawless up to the point the radio link to the aircraft stopped at 6 min 7.1 sec into flight, after three seconds the aircraft would have initiated its Return To Home (RTH) sequence, which appears to be what it has done.
So it has returned to the home point when the radio signal is resumed @ 7 min 0.6 sec, and briefly you have some control before it lands in the water (Autoland as part of the RTH process already initiated). Given that there would be some error in the GPS recorded home point, or that the boat had drifted slightly, or moved from the original home point, what happened might have been anticipated.

What appears unusual to me is that there are no warning messages regarding radio interference at all, which you might expect to see before complete loss of link. Presumably caused by some of the ships equipment.

One good option when flying from a boat would be to set loss of signal action to 'hover' rather than 'RTH' in DJI Go 4.

As you have recovered the aircraft it may be worth setting up a repair case with DJI to let them assess the damage. Although unlikely, it's not impossible that a fault on the RC or aircraft could have caused the loss of link. The battery would not be worth using again I would think, but I've read stories of similar incidents where the aircraft when thoroughly rinsed in fresh water and completely dried out has come back to life. But even then, could it be trusted to fly properly ?

Hello and good day 4U2NVME.  I am sorry to know what happened to your previous flight with your DJI Mavic Pro. I would recommend you contact our support team to start up a ticket for the said drone: https://www.dji.com/support?site=brandsite&from=nav . We have the professional team who would do their best to find out the reason of the incident and then the corresponding resolution would be provided. Please note that DJI will not perform data analysis for cases occurring after the expiry of the warranty period; otherwise, valid charges will apply. Thank for your support.

Aardvark Posted at 5-4 05:39
I'm sorry to read of your loss. Looking at your phantom help log the flight was flawless up to the point the radio link to the aircraft stopped at 6 min 7.1 sec into flight, after three seconds the aircraft would have initiated its Return To Home (RTH) sequence, which appears to be what it has done.
So it has returned to the home point when the radio signal is resumed @ 7 min 0.6 sec, and briefly you have some control before it lands in the water (Autoland as part of the RTH process already initiated). Given that there would be some error in the GPS recorded home point, or that the boat had drifted slightly, or moved from the original home point, what happened might have been anticipated.

Thank you for looking at the reports, we're you able to see the second link work? How much power and by what could blast out my drone like that, I was only like 20 linear feet away or so. Really especially in middle of ocean with so little traffic around.

4U2NVME Posted at 5-4 15:39
Thank you for looking at the reports, we're you able to see the second link work? How much power and by what could blast out my drone like that, I was only like 20 linear feet away or so. Really especially in middle of ocean with so little traffic around.

"Really especially in middle of ocean with so little traffic around. "

Presumably if you're out on the ocean then it is a good size boat or ship you were on. It's nearly impossible to say whether it might be interference from any of the boats radio or radar devices. More likely to be something working in the 2.4 GHz frequencies which are used on a lot of devices. Wifi enabled devices might be the most obvious place to start. Or walkie talkies perhaps.
I noticed when using the Airdata 'HD flight player' mode that no radio signal is being recorded for the first 42.6 seconds after the motors started. Which seems strange, and difficult to identify.

Aardvark Posted at 5-5 02:52
"Really especially in middle of ocean with so little traffic around. "

Presumably if you're out on the ocean then it is a good size boat or ship you were on. It's nearly impossible to say whether it might be interference from any of the boats radio or radar devices. More likely to be something working in the 2.4 GHz frequencies which are used on a lot of devices. Wifi enabled devices might be the most obvious place to start. Or walkie talkies perhaps.

Did that link I provide give you access to all the pages? It was a catamaran, probally 30 feet.. Thank you also for looking... So really in the future if I ever try this again which is highly unlikely, are there things I should try to arrange or find out before doing this? I had no idea the boats radios could be on the same frequencies if that is what you think may have done it...

4U2NVME Posted at 5-5 04:44
Did that link I provide give you access to all the pages? It was a catamaran, probally 30 feet.. Thank you also for looking... So really in the future if I ever try this again which is highly unlikely, are there things I should try to arrange or find out before doing this? I had no idea the boats radios could be on the same frequencies if that is what you think may have done it...

" I had no idea the boats radios could be on the same frequencies if that is what you think may have done it... "

I think that the boats radio or radar is less likely to have caused problems (probably not at all)  than wifi or walkie talkies, which will likely be operating on the unlicensed 2.4GHz frequencies as the aircraft. Was wifi turned off on your display device, that might be one example of a strong 2.4GHz transmission close by.

There are some good guidelines in this other thread about flying over water, and flying from boats:-

https://forum.dji.com/thread-181878-1-1.html

I got the drone apart, its actually quite clean.. I see the ultrasonic board, and the board that seems to have all the radio connections to it has some tape on it with Chinese writing on it.  I wonder if I got an RMA board in here and the last guy complained about radio dropouts!!!! Boy that burn my bacon....

Anybody aware if I can put this board with the ultrasonic sensors in a ultrasonic cleaner... would it destroy the sensors if I were to do that... or because there is no power going to the sensors, should have no effect on them?

Well, some pretty good news I guess, the emergency procedures i did after it crashed seems to have saved most of the drone.  I flew it tonight, and almost everything is working, the only thing not currently working is the front left vision sensor... I'll have to do some research on that and see what it could be...
I did not dunk it in an ultrasonic cleaner, I used a very soft tooth brush and some isopropal alchol and cleaned the board up... and some of what I though was corrision.... fingers crossed it works for the long haul.

4U2NVME Posted at 5-7 19:19
Well, some pretty good news I guess, the emergency procedures i did after it crashed seems to have saved most of the drone.  I flew it tonight, and almost everything is working, the only thing not currently working is the front left vision sensor... I'll have to do some research on that and see what it could be...
I did not dunk it in an ultrasonic cleaner, I used a very soft tooth brush and some isopropal alchol and cleaned the board up... and some of what I though was corrision.... fingers crossed it works for the long haul.

Try and ensure that the board and the aircraft are as dry as possible, some have put them in bags for a few days with descant packs (or dried rice) to absorb any remaining moisture there might be. It would not be good working procedure though to use the same battery (If this is the case). The LiPo batteries are more or less considered unusable if they've taken a dunk. But if no water got into the internals of the battery then who knows.

The battery was tossed, I did not try to save that.  Don't want to play with LIPO' and a possible fire...