Mavic Disappeared Mid-Flight

Dubwilcox · Jul 31, 2017

Earlier today I was flying my Mavic at a beach in Mexico. Everything was excellent, 14 satellites, 54% battery, clear video transmission. I was moving it slightly horizontally, but far from any obstacles. All of a sudden, I got "Aircraft disconnected" on the display, and the prompt about initiating return to home. I said yes, and nothing happened after that. All of the numbers on the remote controller and the app remained frozen as they were. I got up from where I was and I started walking over to where it was (about a 15 minute walk and I knew the battery wouldn't last that long). The remote controller stayed with "Connecting..." for the rest of the time. At some point I turned it off and back on when I realized it wasn't going to reconnect.

It is now completely lost. It soon got dark and it was too tricky to try and get to the top of the hills that surround the beach. I'm heading back there in the morning to look for it. I don't know if it's in the sea or on the rocks. The satellite view shows it right on the border (may even depend on the tide level).

The flight record shows nothing unusual, and even confuses me more. There appears to be no issue other than the aircraft disconnected message at the final moment that it is aloft.

Does anyone know how long the lights will continue flashing if it is still alive? My girlfriend said she saw it flashing on the hill that it was flying over. Even more strangely, my friends who were conducting a ground search said after some of us left to climb, after it was dark, that they saw the drone go up in the air with the lights flashing. They swear it wasn't anything else. One said she assumed it was "trying to look" for me.

I contacted DJI support and they said they have opened a case. Time will tell.

Egika · Jul 31, 2017

Have you tried the "find my Mavic" function in the app? It provides the last known position in case it fell from the sky after losing connection.
If it initiated an RTH after disconnecting and got lost on the way it should be somewhere on a direct line between you and the last known position...
Good luck!

Dubwilcox · Jul 31, 2017

Egika said:
Have you tried the "find my Mavic" function in the app? It provides the last known position in case it fell from the sky after losing connection.
If it initiated an RTH after disconnecting and got lost on the way it should be somewhere on a direct line between you and the last known position...
Good luck!

Yes, I did try that and it shows it just barely over water so I'm afraid that's where it is. Do you know if that would be the absolute last known location before it was damaged? It's not too deep there so I'll see today if it's still in the area for me to salvage from the sea floor or the rocky shore. Painful to think of that kind of fall from 238 feet.

I don't think it attempted a return to home because there were lots of witnesses who never saw it come back from the other side of the beach.

msinger · Jul 31, 2017

Dubwilcox said:
The flight record shows nothing unusual

If you'd like other people to review it, please upload it here and post a link back here.

Dubwilcox · Jul 31, 2017

Here is a link to the flight log from my phone. I'm working on the flight data from the controller.

DJI Flight Log Viewer - PhantomHelp.com

msinger · Aug 1, 2017

At 10m 45.3s in your flight log, the flight mode changed to "Forced Landing" because the throttle was in the down position while the downward sensors detected the ground was near (even though it wasn't). That caused your Mavic to start to auto land at its current location. Since you did nothing to cancel the auto landing, your Mavic continued to land until 11m 42.5s where the downlink dropped (the signal was blocked by the terrain). At that point, the last known location was 24.24302326, -110.1406184 (see the yellow pin below). It was only moving at 5 MPH at that time, so it should be close to that location.

Egika · Aug 1, 2017

One more example of the problems "landing protection = on" can cause.
Better have it switched off

FlyGuy8675309 · Aug 1, 2017

Egika said:
One more example of the problems "landing protection = on" can cause.
Better have it switched off

Great tip. Love this hobby, but it sure can be nerve-wracking.

J3ffrey · Aug 1, 2017

But it said disconnected on his control? Mine did THE EXACT same thing, only difference was I was right below it.. and caught it with a kayak

Dubwilcox · Aug 1, 2017

msinger said:
At 10m 45.3s in your flight log, the flight mode changed to "Forced Landing" because the throttle was in the down position while the downward sensors detected the ground was near (even though it wasn't). That caused your Mavic to start to auto land at its current location. Since you did nothing to cancel the auto landing, your Mavic continued to land until 11m 42.5s where the downlink dropped (the signal was blocked by the terrain). At that point, the last known location was 24.24302326, -110.1406184 (see the yellow pin below). It was only moving at 5 MPH at that time, so it should be close to that location.

View attachment 18563

View attachment 18565

Thank you for your analysis. I want to point out that it didn't advise me that it was in forced landing mode. I only found out about it by looking at the log. Shouldn't there have been some notice that it was doing so?

One of the last things that happened was it asked me if I wanted to initiate RTH due to weak signal and I responded yes. Right after that, the controller announced for the first time that it was landing. I pressed pause, I throttled up. I pressed RTH again on the DJI Go app. Then "Aircraft Disconnected". I walked uphill toward it to get closer to its elevation (still in direct line of sight). It never reconnected. But the last contact is still significantly above the peak of that hill, which is about 100 feet tall. Why wouldn't the downlink continue until it actually lowered itself below the terrain, especially at such a modest speed?

What's also interesting is that I dove around underwater in that area of last GPS contact for about 2 hours yesterday and never found a trace of the Mavic. There are lots of boulders and corals in that zone that should help to anchor it in place or at least keep it in the general area.

Dubwilcox · Aug 1, 2017

FlyGuy8675309 said:
Great tip. Love this hobby, but it sure can be nerve-wracking.

According to the DJI Go app settings, the landing protection is disabled.

J3ffrey · Aug 1, 2017

Mine was as well, and I believe I also had downward sensors off.

msinger · Aug 2, 2017

Dubwilcox said:
Shouldn't there have been some notice that it was doing so?

There isn't, but it would be a nice addition to the DJI GO app. Or, better yet, maybe Forced Landing mode should be cancelled if the IMU altitude has decreased by X feet and the VPS altitude remains the same. I'm sure DJI could do something creative to make this feature work better.

Dubwilcox said:
According to the DJI Go app settings, the landing protection is disabled.

That's odd. The Mavic should never go into Forced Landing mode while that setting is disabled.

iPa64 · Aug 5, 2017

I don't understand why it should be better to switch off "landing protection"?
I don't understand why "landing protection" can be a problem, in fact I think it's better to have it on.

msinger · Aug 5, 2017

iPa64 said:
I don't understand why "landing protection" can be a problem

Check out the first post above. The OP landed his Mavic in the water because he did not know his Mavic was auto landing due to the auto switch to forced landing mode.

AnzacJack · Aug 5, 2017

is there a thread that highlights the ideal best settings for the mavic with an explanation ?
would make a good sticky for new flyers

CashCache · Aug 5, 2017

Dubwilcox said:
According to the DJI Go app settings, the landing protection is disabled.

I think this defaults to off when not connected to your Mavic. You would need it connected to see what it was really set at.

CashCache · Aug 5, 2017

What firmware version are you on? I've lost connection many times and I don't recall it ever asking me to confirm I wanted to RTH. I'm on .400.

Chadnovz · Aug 5, 2017

Egika said:
One more example of the problems "landing protection = on" can cause.
Better have it switched off

What do you mean by this sir

Michael Ainsworth · Aug 6, 2017

Chadnovz said:
What do you mean by this sir

For some reason there have been many instances of the MP Landing unintentionally over water or other reflective surfaces.
It appears that the sensors become confused as to the correct height, think the MP is lower than it is and initiates a forced Landing sequence.
I keep Landing Protection off and just come in gently when I land.
Also makes hand launch and catch easier.