Mavic disconnected, no RTH & is lost

[timpani]

I fly my Mavic Pro regularly, usually over my house capturing the sunset view I keep the firmware updated and it has been behaving normally.

But on Dec 30h the Mavic Pro suddenly disconnected & is now lost.
I was flying at a distance of 750m and was 50m high, above water - filming some yachts.
I was shooting video at the time, I had 17 satellites and 70% battery, no warnigns of any kind.
Suddenly all signal disconnected - no video, no control.

When I took off from a beach it registered the RTH location, and RTH was set to fly home at min imum height of 30m
and there were no obstacles between me & the last location of the drone.

At first I waited for the drone to RTH, and reconnect. Nothing happened.
I pushed the RTH button on the controller, it beeped but nothing else happened.
I then waited for the drone to RTH when its battery got to 30%. Nothing happened.

So my Mavic Pro disappeared, and is presumably at the bottom of the harbour.

I retrieved all data from the app including video, flight data etc
It shows what I explain above - drone is working normally,
battery has a linear decrease from 100% to 70% at point of disconnect.
17 satellites, no warnings during the flight at all.

But at the point of disconnect all data ends, and the final GPS position
is in the middle of the harbour, where the cached video ended.

Why no RTH?
Was there a power loss? If so, how?
The flight records show the battery had a linear decline from 100% to 70%
There was no low power warning. Why would the drone suddenly lose all power?
The video shows i did not hit anything. How could there be an instant 100% power loss?

Or did its firmware crash?
How could it suddenly stop functioning?


I'd appreciate any suggestions or advice.

I contacted DJI support, sent them all the data and their response was:
there is no record of a failure, and "we could not verify what happened afterwards."
so they offered me 30% discount on a replacement Mavic Pro.

But here is the thing: my Mavic is only 8months old, so still under warranty.
The flight data shows I was using the drone under completely normal circumstances,
and yet they will not honour their own warranty.

"For your claimed case CAS-1366163-J5Q3N7, we have already finished the analysis, and the result is as follows:
1. The aircraft worked in GPS mode and responsed to the pilot's command well;
2. At T=09:15, H=52 m, D=753.5 m, the pilot pushed forward the Elevator stick and moved the Rudder stick leftwards, then the record ended;
3. The home point: -41.1121000 174.8527440, the last point: -41.1183687 174.8493132.

With the record ended without any sign of abnormality, we could not verify what happened afterwards."

 

[HapK]

That is a sad story. Too often we read about drones just flying away and lost.
This was the first time I have read about a complete disconnect.
Even more sad to me is that Mavic didn't replace your aircraft.
They make a ridiculous amount of money and you appear to be a responsible owner that sent them proper proof.
I would like to ask you what you plan to do next ? I would not want to support Mavic but would still want to fly. Maybe build your own drone.

 

[LivinLarge]

I had a similar experience. I was only about 30 feet away and not over water. The RC disconnected from the Mavic and I had no way to control it. Fortunately, it returned to home on its own and hovered but I could not get it to land. Finally the battery got low and it came down safely. DJI had no explanation except to say upgrade firmware.
On loss of signal from the remote, yours, should have returned to home. Perhaps it was a complete loss of power. I don't see how this is pilot error. I would contact them again and ask what you could have done differently.

 

[timpani]

Thanks - it seems incredibly short sighted of them - I appreciate support staff follow a script and have no authority.
I asked for this issue to be escalated and re-assessed but received a fairly sanctimonious reply.

Next?
I simply can't spend more money on a product if (a) it could happen again and (b) the company who makes it won't honour their own warranty.
I wont deal with companies who do not honour their own warranty.
So I will wait for a proper response and if it is not forthcoming,
first I will sell all my other 5 Mavic batteries, chargers, controller, case, and DJI googles.
Then I will cancel my plans for future upgrade to Phantom 5 Pro or Inspire, which I was aiming to do later this year.
Then I will start researching other drone companies.

Seems so bizzare to be in this situation.
Before the Mavic I owned a Phantom 3 Pro for many years, so I can keep flying it.
It disconnected once in many years of use, and that was due to being on edge of range.
It started a RTH and within a minute was back in range & reconnected, and I carried on flying.

This is a catastrophic fault with the Mavic Pro.
If I had been flying low over land when it happened, maybe I could have retrieved the drone.
But I fly over water very often, and apart from a total failure such as this, it should be no problem.

I have replied to support again... will update this when I hear back

 

[timpani]

Here is link to youtube of video I was shooting when disconnect happened...

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When the video ends that was the point when all signal & control was lost

 

[Anthony]

Here is link to youtube of video I was shooting when disconnect happened...

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When the video ends that was the point when all signal & control was lost

Are you sure your mavic wasn't push by the wind towards that high set of trees ? The wind does look strong enough to blow your mavic away from the lake.

 

[timpani]

So you're suggesting the Mavic Pro disconnected all video & control, ignored RTH (despite having confirmed RTH location, 70% battery and 17 satellites) and then drifted a long way to those trees? I was at 50m height when I lost control, RTH height was set to 30m... So it would have to drift a long way and decrease in height a lot, all without any control or input from me.
Anything is possible, but why do you think it would do that?
When it disconnected from the controller, it should have started a RTH immediately.
Why didn't it is the question

 

[Anthony]

So you're suggesting the Mavic Pro disconnected all video & control, ignored RTH (despite having confirmed RTH location, 70% battery and 17 satellites) and then drifted a long way to those trees? I was at 50m height when I lost control, RTH height was set to 30m... So it would have to drift a long way and decrease in height a lot, all without any control or input from me.
Anything is possible, but why do you think it would do that?
When it disconnected from the controller, it should have started a RTH immediately.
Why didn't it is the question

Without input from you it would have come to a dead stop but the wind would have pushed it so it is possible to calculate the wind speed and direction for that day and the time your mavic would have stayed in the air, once it hit 10 % power it could have initiated the auto land so it's possible that with 70% power left at the point you lost conection it made it to dry land...

Did you have your contact details on your Mavic?

Have you loaded your flight log form your DJI GO ?

If not load it here DJI Flight Log Viewer this might help you work out were it may have drifted to.

 

[timpani]

The Mavic > Controller disconnected all signals simultaneously, so it wasn't waiting for input from me. The Mavic would know straight away it had disconnected from the controller, and in that case the firmware should follow the RTH setting which was 'return to take off location', which is shown in the Flight Log... So there is no reason it would hover after disconnect, it faulted on the RTH fail safe. Then once the battery got down to 30% it was also set to RTH, but it did not act on that failsafe either.

All flight logs & data have been sent to DJI, flight log is here:
DJI Flight Log Viewer - PhantomHelp.com

No contact info was on the drone. It would seem very odd to me that it would take off in some other direction. If it could still fly why did it not RTH? I flew my P3P out of range once, and as soon as it disconnected it started a RTH and reconnected as soon as it was back in range.
But if the Mavic had been out of range I would have received some warning and/or video signal degradation. As per the flight log it was behaving 100% normally, no warnings, no errors. Then... disconnect, no RTH

 

[Anthony]

No one knows why your Mavic disconected nor what state it was in after it did .... it could have dropped into ATTI mode after the disconection which might explain why it did not RTH .... The point I'm trying to make here is once it disconnected it Would have been influenced by the wind. What was the wind speed and direction at the hight you were flying at on this day ??

And if you are flying above your set RTH hight the Mavic would not descend to the RTH hight at all it would stay at it's current hight and fly home in normal circumstances.

 

[Callum]

No one knows why your Mavic disconected nor what state it was in after it did .... it could have dropped into ATTI mode after the disconection which might explain why it did not RTH .... The point I'm trying to make here is once it disconnected it Would have been influenced by the wind. What was the wind speed and direction at the hight you were flying at on this day ??

And if you are flying above your set RTH hight the Mavic would not descend to the RTH hight at all it would stay at it's current hight and fly home in normal circumstances.

That would be pretty bad luck, complete signal loss and an IMU discrepancy or GPS loss causing atti mode.

That's a catastrophic event in itself with virtually no means of recovery and should be covered under warranty.

It's unacceptable for a £1000 quad just to vanish with no trace or user error.

I'd get over to the DJI forum and kick up a stink, see if one of the forum team can have it reviewed.

 

[timpani]

Thanks, I started a thread there at same time as this one:
Mavic Pro disconnected & lost

 

[colinfowler]

no reason for RTH not to kick in, BUT if its returning at 15mph with a 20mph head wind its going to go away at 5mph

 

[timpani]

Sure, but as the flight path shows, I flew in every direction with no real problem and it only took 30% of the battery to reach the furthest point. And during that time I flew a big 180 around the yachts, with & against the wind - I'll post an image of the flight path....
When the RTH should have kicked in I had 70% battery left, which was plenty of power to get home under such circumstances... And if signal loss was what should have started the RTH, the Mavic should have reconnected once the RTH started and it was moving closer to me. It never did.

 

[Callum]

no reason for RTH not to kick in, BUT if its returning at 15mph with a 20mph head wind its going to go away at 5mph

That makes no sense. If it's returning at 15mph, it's returning at 15mph.

There was no wind warnings during flight, it's all to easy to suggest things that might have happened.

People seem to naturally geared towards blaming pilot on here.

 

[colinfowler]

That makes no sense. If it's returning at 15mph, it's returning at 15mph.

 

[timpani]

Sure but you know what he means - if it was RTH head on into a gale force wind it would expire the battery faster...

 

[timpani]

View media item 1527
flight path - it took 30% of battery to fly & shoot video until the Mavic disconnected...
70% of battery left, and no abnormalities with battery cell use, as per flight record
DJI Flight Log Viewer - PhantomHelp.com

 

[colinfowler]

That makes no sense. If it's returning at 15mph, it's returning at 15mph.

There was no wind warnings during flight, it's all to easy to suggest things that might have happened.

People seem to naturally geared towards blaming pilot on here.

not blaming the pilot at all, and nobody knows what the wind speed and direction was at the mavics position and altitude at the time of RTH

 

[Callum]

not blaming the pilot at all, and nobody knows what the wind speed and direction was at the mavics position and altitude at the time of RTH

Sorry mate didn't mean to come across harsh, long nightshift, should really get to my bed.

At around 5min 30s he is flying a heading about 15 degrees off that of final position RTH .

Assuming he is full pitch forward , he is averaging around 9mph, so a 13mph+ headwind on RTH if he had OA switched on could be possible.

He did only have 750m to travel and 70% battery.

Also reported no warnings during flight, I took this to include wind.

If wind was the issue he could have switched to sport mode had it not disconnected.

Would be great if Mavic could automatically switch to sport mode or increase max speed on RTH if it is not making progress when full pitch.