Wakeboarding?! Lost in Lake...

[brnelso]

I have about 100 flights on my Mavic and took it out on a boat for the first time this morning. Did several take-offs/landings from the boat, great videos, blah blah...SPLASH!!

On the last flight, I got a low battery warning (23%), stopped the boat and started descending to land. At this point, the home point was still at another point on the lake. RTH triggered, I cancelled...there was a notification of bad signal, then signal lost completely...all within a matter of seconds.

Unfortunately, this was the only time of the day day I was above about 30' and wasn't able to visually locate. Was unable to regain signal at all, so returned the boat to original Home Point with no success.

Was in Sport mode and it appears full left stick "down" when lost signal......could it be this downward path continued when the signal was lost? That seems like a poor programming choice, if so.

This is my first time using HD (log below), but I would greatly appreciate any feedback on what might have gone wrong and if this possibly could have been a system malfunction.

Here is the log:

Airdata UAV - Flight Data Analysis for Drones

As far as I know, there isn't a way to set a home point that is neither the drone or remote/phone location...correct? Seems easy enough and would certainly help for a situation like this.

 

[Plawa]

Man that sucks... sorry to be say but having done exactly this (shooting wakeboarding from a boat) your first mistake was to take off with 50% battery.. The first time I let my battery drop to about 30% and decided to land the same exact thing happened to me - drone decided to go back to its HP which was in the middle of a lake, I was able to cancel that via Sport mode and then land with about 20%.. So I switched Smart RTH off and now I land anytime I get close to 50%.. it's just not worth it.

What's your setting for signal loss? If RTH then the drone continued to its last recorded HP at whatever altitude was set for RTH (or at its current altitude if it was above it).

You can set the HP dynamically with Litchi, not with DJI Go 4... (not sure if Litchi can set HP to a arbitrary location).

As for the signal loss... you'd need the data file from the Mavic to investigate that properly..

Found a screenshot.. this is exactly what you don't want to see :/

 

[Cyberpower678]

I have about 100 flights on my Mavic and took it out on a boat for the first time this morning. Did several take-offs/landings from the boat, great videos, blah blah...SPLASH!!

On the last flight, I got a low battery warning (23%), stopped the boat and started descending to land. At this point, the home point was still at another point on the lake. RTH triggered, I cancelled...there was a notification of bad signal, then signal lost completely...all within a matter of seconds.

Unfortunately, this was the only time of the day day I was above about 30' and wasn't able to visually locate. Was unable to regain signal at all, so returned the boat to original Home Point with no success.

Was in Sport mode and it appears full left stick "down" when lost signal......could it be this downward path continued when the signal was lost? That seems like a poor programming choice, if so.

This is my first time using HD (log below), but I would greatly appreciate any feedback on what might have gone wrong and if this possibly could have been a system malfunction.

Here is the log:

Airdata UAV - Flight Data Analysis for Drones

As far as I know, there isn't a way to set a home point that is neither the drone or remote/phone location...correct? Seems easy enough and would certainly help for a situation like this.

Can you please upload the flight log to the site below?

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

 

[brnelso]

Plawa, agreed...it's just frustrating since I've operated the drone many, many times all the way to the low battery alarm. If I'm honest...it's probably almost every time. Of course I recognize the difference with a "moving" (or liquid!) Home Point.

Cyberpower678, please see the Phantomhelp log below. Anything you can tell from this?
DJI Flight Log Viewer - PhantomHelp.com

 

[brnelso]

I'm having a hard time reconciling the flight log with my memory of the event... Here's what I remember:

1) Low battery alarm
2) I begin descending with left stick
3) Auto RTH triggered
4) Release stick
5) RTH cancelled
6) Brief interference alarm shown
7) Signal loss

The last logged event is at 19' with full down left stick. Hypothetically, if I did have full down stick and the drone tried to land, I would expect several additional data points below 19' as it approached the water....correct?

Does that descent rate look faster than usual the last 10 seconds? I guess it can technically do 9.8 fps, but I've never seen it actually move that fast....way slower usually.

 

[Plawa]

Interested in what the gurus say but I see variation between GPS and VPS altitude towards the end that may have ended in the drone crashing into water while thinking it's still 19ft up.. VPS not working properly above water?

 

[brnelso]

This may not be related to the issue...

During the first flight of the day, I switched to Sport mode mid flight and had zero control of the drone. It just hovered about 30-40'. Had to turn the boat around, go back to it...then realized switching back to P mode was the only way to get any response.

Again, I was in Sport mode before the crash.

 

[Cyberpower678]

Plawa, agreed...it's just frustrating since I've operated the drone many, many times all the way to the low battery alarm. If I'm honest...it's probably almost every time. Of course I recognize the difference with a "moving" (or liquid!) Home Point.

Cyberpower678, please see the Phantomhelp log below. Anything you can tell from this?
DJI Flight Log Viewer - PhantomHelp.com

I'll have a look tomorrow, but at first glance, your voltage in your battery dropped to below minimum accepted threshold. It may have emergency landed in the water because of it.

 

[Plawa]

I'll have a look tomorrow, but at first glance, your voltage in your battery dropped to below minimum accepted threshold. It may have emergency landed in the water because of it.

Isn't that closer to 3.2V?

 

[Cyberpower678]

Isn't that closer to 3.2V?

I thought it was 3.5V. They are connected in series to sum up to at least 10.5 V. Ideal values are 11-12V

 

[msinger]

According to your flight log, you were flying at full stick forward and downward at the end of the flight (e.g. coming down for a landing pretty hot). When your Mavic disconnected at the end of the flight log, you were about 0.24 miles (1,267 feet) away from the Mavic. Your flight log shows you crashed into the water at a speed of about 35 MPH.

If you check out the "VPS Altitude" column in my log viewer, you can see the downward sensors were detecting the surface of the water prior to the impact.