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Almost lost my Mavic while ocean fishing

Cutaway

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Can some one help me "guess" what could've caused this near-miss incident (see attached KLM file).

In a nutshell, I launched my Mavic Pro from the hand while ocean fishing on a boat. It flew great for about ~5 minutes...then it freaked out saying it lost connection and began to returned home. The scary part was that it began to LAND!!! Finally, I regained connection and landed back on my hand.

15+ GPS connections. Kept the Mavic in VLOS the whole time. The ONLY thing I can think of is the STUPID firmware upgrade the night before. Any other guesses? My Mavic Pro has never done this before...

Thanks in advance!!!
 

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msinger

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Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.
 

Photoxperts

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Did you calibrate it before taking off? There are times when the system looses its Tracking and acts crazy.
 

Cutaway

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Here is the video of the Mavic Pro going rogue (at the end)...

 

msinger

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In a nutshell, I launched my Mavic Pro from the hand while ocean fishing on a boat. It flew great for about ~5 minutes...then it freaked out saying it lost connection and began to returned home. The scary part was that it began to LAND!
Here's what I see in your flight log:

3m 31.5s: Downlink dropped
3m 36s: Downlink restored
.
3m 42.5s: Downlink dropped
4m 49s: Downlink restored & Mavic was returning home since the remote controller signal was also lost at some point
.
4m 54.8s: RTH cancelled (Mavic was 43 feet from home point)
.
5m 19.9s: Home point updated (Mavic now 1,365 feet from home point)
5m 26s: Tapped auto land icon on left side of DJI GO (possibly meant to tap RTH instead?)
5m 40.4s: Cancelled auto landing
.
6m 5.7s: Started manually flying back to the home point


Kept the Mavic in VLOS the whole time
Are you sure the boat was not coming in between the remote controller and Mavic at a few points in your flight (like at 3m 31.5s and 3m 42.5s)?

Your Mavic was flying about 20 feet above the surface of the water prior to the point where it started returning home. At 1,150 feet away from the boat (about where RTH was initiated), I'm thinking it would have been possible for the signal to be blocked if you were flying low in front of the boat like this:

Location1.jpg


Here is the video of the Mavic Pro going rogue (at the end)...
Where exactly in this video is your Mavic going rogue?
 
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Cutaway

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Here's what I see in your flight log:

3m 31.5s: Downlink dropped
3m 36s: Downlink restored
.
3m 42.5s: Downlink dropped
4m 49s: Downlink restored & Mavic was returning home since the remote controller signal was also lost at some point
.
4m 54.8s: RTH cancelled (Mavic was 43 feet from home point)
.
5m 19.9s: Home point updated (Mavic now 1,365 feet from home point)
5m 26s: Tapped auto land icon on left side of DJI GO (possibly meant to tap RTH instead?)
5m 40.4s: Cancelled auto landing
.
6m 5.7s: Started manually flying back to the home point



Are you sure the boat was not coming in between the remote controller and Mavic at a few points in your flight (like at 3m 31.5s and 3m 42.5s)?

Your Mavic was flying about 20 feet above the surface of the water prior to the point where it started returning home. At 1,150 feet away from the boat (about where RTH was initiated), I'm thinking it would have been possible for the signal to be blocked if you were flying low in front of the boat like this:

View attachment 42035



Where exactly in this video is your Mavic going rogue?
Thanks @msinger for the thoughtful read out. Here are some more thoughts:

1) In a thhread about the recent firmware update and idsues, another pilot had very similar incident . Thankfully his flight was over an open field . Lost signal suddenly and the mavic tried to RTH .

2) I keep a close eye on the GPS and radio signal strengths frequently when I fly. On this flight, I don't recall it being low (4+ bars).

3) Do you think the Marine navigation and radio equipments interfered? I am not certain but none should have messed with the wifi bands .

4) When the Mavic finally freaked, it was behind the boat and the controller was pointed right at it.

5) A few folks commented about the altitude being only 20 ft. Would that contributed possibly?

6) It was never 1,150 feet away from the controller . I think it was 1,150 feet from the home point.

Thanks again!
 

msinger

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Do you think the Marine navigation and radio equipments interfered?
I'm not sure. I was thinking the signal could have been degraded/blocked if you were flying low and your Mavic was in front of the boat. If you were only flying low while it was behind the boat, then the boat itself wouldn't have caused that issue.

When the Mavic finally freaked, it was behind the boat and the controller was pointed right at it.
Can you tell us some more about the freaking out part? What exactly did it do?

It was never 1,150 feet away from the controller . I think it was 1,150 feet from the home point.
When you reset the home point to the remote controller mid-flight, your flight log shows your RC and Mavic were located here:

upload_2018-7-14_12-47-5.png

If those points are correct, your Mavic would have been 1,365 feet away from the remote controller at that point.
 

Cutaway

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Freaked out is the technical lingo for when the Mavic said lost signal. ;)

When it flew back to home point I could not locate the Mavic visually. I guess that's when it was 1,354 ft. away.

So when the signal was re-established and said it was auto-landung, I stopped it using the hardware pause button on the controller. Then, I used the software to set the home point to my RC location.

Then I saw the directional indicator on the software and flew it back to me.

I am blaming the **** firmware update. I am going to revert to previous version...
 

Former Member

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Freaked out is the technical lingo for when the Mavic said lost signal. ;)

When it flew back to home point I could not locate the Mavic visually. I guess that's when it was 1,354 ft. away.

So when the signal was re-established and said it was auto-landung, I stopped it using the hardware pause button on the controller. Then, I used the software to set the home point to my RC location.

Then I saw the directional indicator on the software and flew it back to me.

I am blaming the **** firmware update. I am going to revert to previous version...
Alot of people are doing the same thing.
 

msinger

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Freaked out is the technical lingo for when the Mavic said lost signal
Got it. Thanks for explaining :)

If you plot the GPS data on a map, you will see the boat was following behind the Mavic right before the RC signal disconnected. The blue points below are the boat and the green points are your Mavic.

upload_2018-7-14_15-20-51.png

Since your Mavic was flying close to the water, the boat likely blocked the RC signal.


So when the signal was re-established and said it was auto-landung, I stopped it using the hardware pause button on the controller. Then, I used the software to set the home point to my RC location.
Your flight log shows you manually updated the home point 25 seconds after the RC signal was re-established. And then 7 seconds after that, you tapped the auto land icon on the left side of DJI GO.

upload_2018-7-14_15-17-56.png


That's a common mistake since DJI unfortunately located that icon right next to the RTH icon.
 

Cutaway

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Got it. Thanks for explaining :)

If you plot the GPS data on a map, you will see the boat was following behind the Mavic right before the RC signal disconnected. The blue points below are the boat and the green points are your Mavic.

View attachment 42063

Since your Mavic was flying close to the water, the boat likely blocked the RC signal.



Your flight log shows you manually updated the home point 25 seconds after the RC signal was re-established. And then 7 seconds after that, you tapped the auto land icon on the left side of DJI GO.

View attachment 42062


That's a common mistake since DJI unfortunately located that icon right next to the RTH icon.
I can see how I may have pushed the "auto land" icon. Even though I had trained myself to alway use the hardware RTH button on the controller, in the moment of panic, that is a plausible explanation. But, does it not auto land when RTH is initiated upon signal loss?

Also, it's a new lesson for me but hard to swallow the possibility that the Mavic Pro that can fly 4 miles BVLOS experienced a signal loss within 50 ft. because the fishing boat's cabin was blocking it.

Thank you, thank you for the analysis and feedback. So awesome to have a community here. Cheers.
 

MrsTreat

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I can see how I may have pushed the "auto land" icon. Even though I had trained myself to alway use the hardware RTH button on the controller, in the moment of panic, that is a plausible explanation. But, does it not auto land when RTH is initiated upon signal loss?

Also, it's a new lesson for me but hard to swallow the possibility that the Mavic Pro that can fly 4 miles BVLOS experienced a signal loss within 50 ft. because the fishing boat's cabin was blocking it.

Thank you, thank you for the analysis and feedback. So awesome to have a community here. Cheers.
Line of sight explains a 50ft signal loss. Try listening to an FM radio in a city with lots of high rises. Similar effect.
 

rfc

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Could "signal interference" show up as signal loss? The vessel looks like it has radar, HF radios etc. Maybe even wifi too. Probably different frequencies, but the signal strength of either could easily be an order of magnitude higher than the R/C-A/C link. Just wondering.
 
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dewster

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Nice boat. I saw one video of P4 owner that claims navigation/communication equipment on a cruise ship prevented him from recovering his craft.

DJI used to warn against flying over monochromatic surfaces such as large bodies of water and snow. It confuses the downward sensors/camera. Theres an early video on YouTube of a Mavic going crazy while flying low over snow.

Flying low over water with the ultrasonic sensors on can cause variations in height. I think they work below 30 feet.

And yes... I had disconnects with one of DJI’s recent updates. I use an Android device now to keep my craft offline as much as possible and an earlier version of GO4 that’s stable.
 

msinger

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does it not auto land when RTH is initiated upon signal loss?
Using the default setting in DJI GO, your Mavic will start returning home 3 seconds after the remote controller signal is lost. In your case, that's what your Mavic did (according to your flight log).

If you'd prefer your Mavic to auto land on signal loss (not recommended when flying over water), you can configure that setting in the following section of DJI GO:

DJI-GO-RC-Signal-Lost.jpg
 

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