Help!... Mavic Air dropped out of sky into lake!

[Bergumbira]

30% battery and over a lake is not good either.

Especially without floats

 

[jmillingworth]

No - that's definitely not the case, because the pitch excursion and deceleration that follows the elevator being centered could only have occurred while airborne. Application of the throttle was 1.5 seconds later. At this point I'm pretty certain that the drop was simply caused by the sudden deceleration. It's very hard for the aircraft to hold altitude perfectly when pitched at 40°, and some loss of altitude is very common. Pilots have often commented on that, and a number of crashes have occurred because of it.

Ok thanks for your help @sar104... seems like the conclusion is I was too close to the water then at the end of the day? I still don’t feel the data is showing what happened as the three of us watched but I have no explanation and what you have explained makes perfect sense.
Thanks again, will speak to DJI and see what they say, if they agree the I will make use of the DJI Care Refresh.
Thanks again

 

[JoBri]

This is 100% not true. Stop making stuff up.

This is my stuff and it is only my idea I do have But in generalization, this is undecided or exactly not true

 

[jmillingworth]

@sar104 I have managed to get the footage from the other drone that was flying that day and you can just see my MA in the footage as it flies and then drops... if you look carefully! I have zoomed into the footage part way through to make it easier to see. Have a look and see what you think - I am positive if you look carefully you will see the drone does not have a severe pitch change at the point it drops into the water... it is also slightly higher than I remember.... probably more like 3 metres or so.

Video here: Dropbox - Video 23-08-2018, 23 00 04.mov

 

[sar104]

@sar104 I have managed to get the footage from the other drone that was flying that day and you can just see my MA in the footage as it flies and then drops... if you look carefully! I have zoomed into the footage part way through to make it easier to see. Have a look and see what you think - I am positive if you look carefully you will see the drone does not have a severe pitch change at the point it drops into the water... it is also slightly higher than I remember.... probably more like 3 metres or so.

Video here: Dropbox - Video 23-08-2018, 23 00 04.mov

Very interesting. But it does appear to me that it goes from pitched forwards to pitched back as it drops, and that really has to be the case since otherwise it would have hit the water with significant forward speed. That is a pretty big drop - larger than I would expect even in sport mode, but it was severe braking. Overall inconclusive, but I would say that it is not inconsistent with the logged data or the previous hypothesis.

 

[jmillingworth]

Very interesting. But it does appear to me that it goes from pitched forwards to pitched back as it drops, and that really has to be the case since otherwise it would have hit the water with significant forward speed. That is a pretty big drop - larger than I would expect even in sport mode, but it was severe braking. Overall inconclusive, but I would say that it is not inconsistent with the logged data or the previous hypothesis.

Thanks again for looking

 

[RayOZ]

I think we need an experiment with MA and MP. Fly full speed in sports mode and stop, and see how much the AC drop in altitude. Obviously at a good height and NOT over water.
I think it'll something everyone can take note of when they are flying in sports mode.
Weather isn't too good this weekend for me to test. I hardly fly in sports mode, and I tend to ease forward and slow stop so I don't stress the motors of my MP.

OP, I guess all you can do it send it off to DJI and see what they say. Or extract the .dat file, give that to DJI to see if they think it's a malfunction and would replace for free. Otherwise, it's claiming DJI Care Refresh or finding a repairer.

 

[sar104]

I think we need an experiment with MA and MP. Fly full speed in sports mode and stop, and see how much the AC drop in altitude. Obviously at a good height and NOT over water.
I think it'll something everyone can take note of when they are flying in sports mode.
Weather isn't too good this weekend for me to test. I hardly fly in sports mode, and I tend to ease forward and slow stop so I don't stress the motors of my MP.

OP, I guess all you can do it send it off to DJI and see what they say. Or extract the .dat file, give that to DJI to see if they think it's a malfunction and would replace for free. Otherwise, it's claiming DJI Care Refresh or finding a repairer.

It is definitely worth asking DJI, especially as the video is available to back up the log data. My line would be that it should not drop that far on under braking and if it does then it implies that the maximum pitch angle is too high and possibly the sport mode stick gains are set incorrectly.

 

[Koelkop]

I have tested the stopping capabilities of my mpp by going full speed forward and pressing the pause button. It sqauts back at something like a 45° angle without losing any significant altitude

 

[jmillingworth]

Hi All,

Wanted to drop you a quick update.....

After a considerable amount of time and effort (lots of correspondence to and from DJI) I have managed to get this replaced under warranty today... so almost 2 months after they had received the drone to investigate the issues.

They could not pull any data off the drone due to the water damage so all they had to go on was the Flight Data from the mobile device.

I got the feeling they were being difficult just to try and make me pay for the repair, however I persisted and did not take their (very poor) arguments and fought back with logical questions and reasoning.

Eventually after not hearing back from them for almost 2 weeks, I chased up a response from my last communication saying they had 24 hours to respond and today, miraculously they have decided to replace the drone under warranty.

Just like to say thanks for everyones input, especially @sar104, and hope to have some time to fly the drone before the British winter kicks in!

Thanks,

Jonny

 

[sar104]

Hi All,

Wanted to drop you a quick update.....

After a considerable amount of time and effort (lots of correspondence to and from DJI) I have managed to get this replaced under warranty today... so almost 2 months after they had received the drone to investigate the issues.

They could not pull any data off the drone due to the water damage so all they had to go on was the Flight Data from the mobile device.

I got the feeling they were being difficult just to try and make me pay for the repair, however I persisted and did not take their (very poor) arguments and fought back with logical questions and reasoning.

Eventually after not hearing back from them for almost 2 weeks, I chased up a response from my last communication saying they had 24 hours to respond and today, miraculously they have decided to replace the drone under warranty.

Just like to say thanks for everyones input, especially @sar104, and hope to have some time to fly the drone before the British winter kicks in!

Thanks,

Jonny

OK - good result. I'm guessing that they agreed that the loss of height on braking was excessive.

 

[jmillingworth]

OK - good result. I'm guessing that they agreed that the loss of height on braking was excessive.

They did not even mention anything about the loss of height due to braking.
Their analysis (if that is what you can call it) was very basic. They did not look into the detail as much as you did. The went more down the line of 'we can't pull the data off the drone and the flight log stops abruptly therefore we can't determine the actual cause is a faulty drone'.
They then offered me two options, pay for repair (around £400) or use my DJI care Refresh.

As they had not apportioned any pilot error in their investigation, I argued that they can't force me to pay for it. They then offered me a discount of 30% off repair price, or to be able to use my DJI Care Refresh.

I persisted and said I want the issue raising higher as whilst they may not be able to determine the actual cause due to lack of data, they have not once been able to but the error down to the Pilot. They even stated that at the end of the log the drone was travelling forwards/up. So I used their findings as my argument.

They then cam back with some absolute rubbish stating that I could have turned my mobile device off, or disconnected the cable etc and therefore they could not rule out Pilot error. So I stated that I had a screen shot of the app after the drone hits the water, so a timestamp would prove my mobile device was turned on. I also stated that under what circumstances is the drone expected to 'drop' as I was under the impression that failsafe should kick in with controller disconnect and the drone should fly back to the home point.

After a bit more forwards and backwards with emails, they had another engineer look at the data who then came back with a screenshot of when downward elevator was pressed. I went back and stated that after the downward elevator was pressed there was a further 10 secs of drone flight before the end of the log, and the drone travels a further 160ft away from the home point, so what the engineer is looking at has nothing to do with the 'drop' and the drone hitting the water.

They sat on that for almost two weeks so I sent a chaser email, still had not heard anything back, so sent another chaser and finally they came back with:

According to the data at the flight time T=12:51, the relative height suddenly ascended without control because the barometers was affected by the water surface, this would cause mixed height issue and the aircraft would lost altitude. Free warranty, please process.

So that is were we are at... I got a warranty repair so am happy.... although I have to say their customer service is not good in my opinion and you certainly have to fight your corner.

I am just thankful I managed to retrieve it out of the lake in the first place! Also, just want to say thanks for everyones input.

 

[ac0j]

Hi everyone, new to this forum but have seen some really knowledgable guys so was hoping for some assistance.

I was taking my new (24 hours old) magic air for a spin, went over a lake to take a photo and with over 30% power left in the battery it just dropped out of the sky... no warning. Can anyone help with why this might have happened and where I stand with DJI about a replacement?

You forgot to mention the part where you got it too close to the water and partially submerged it before it “dropped out of the sky”. In your original post. . Glad you got them to believe it was a mechanical error.

 

[Sprocket]

Good thing they didn't see the video. Otherwise they would have seen the goose on the far left stand up in the water and see the little bitty sawed off doublebarrel shotgun that brought your drone down.
BTW, in the U.S of A., you could be charged with molesting migratory waterfowl by flying that close to them. Just sayin"

 

[jmillingworth]

Good thing they didn't see the video. Otherwise they would have seen the goose on the far left stand up in the water and see the little bitty sawed off doublebarrel shotgun that brought your drone down.
BTW, in the U.S of A., you could be charged with molesting migratory waterfowl by flying that close to them. Just sayin"

I sent them the video so they could see the drop... their response was that they could not match the video up to the data as it was not from the drone itself... so they could not be sure that when the drone hit the water was when the flight log ended.

 

[jmillingworth]

You forgot to mention the part where you got it too close to the water and partially submerged it before it “dropped out of the sky”. In your original post. . Glad you got them to believe it was a mechanical error.

haha.. nice try, although you can clearly see that was not the case!