Hey everyone,

So I'm minus a brand new Mavic from a trip to Tasmanaia, AU. I appreciate this post is quite long but I'm a bit confused so will try to lay out all the info here.

The firmware was also update and I had fully calibrated everything after the update. Including the controller. Another key point is that the Compass Error message I can see in the Flight Records did not come up on my screen whilst taking off. When reviewing the flight from the app and watching the live readouts, it does not show up.

The location was at Cape Raoul lookout in Tasmania. It’s a 30 minute drive from a very small town called Nubeena. Most of the drive is down a dirt track as it’s very remote area. I then had to walk for 1.5 hours to the lookout. There are no other buildings or man made objects for many many kms around.

I took off with the intention of recording to forward movement videos in two directions. I was aware of the wind but was sheltered and saw from forecasts it was not anything extreme of above the advised flying conditions. I had just finished the second movement and took away from the forward throttle. My drone however was still moving. I looked at the drone and screen and couldn’t understand why it was moving. I’d watched videos of the Mavic in very strong winds and know how it behaves flying and through the video stream. It was not struggling. I then heard a beep and saw the battery overload message on my screen (flight time was 02.07) I had an immediate flash back of my Phantom 4 falling straight out of the sky the previous year and expected that was the end of the Mavic. 8 seconds later I set the Return to home function. I had now lost the line of sight as it was drifting away so used my video monitor and data read outs. I was confused why it was moving away so fast under RTH. I adjusted my gimbal to assess the landscape for a point of reference. At 03.09 flight time, I cancelled RTH and it was still flying away at speed. I engaged full throttle but the distance kept increasing at a rapid rate. The horizontal speed didn’t change when full throttle was at 100% or 0%. I tried RTH again but nothing happened.  I turned the drone to face a different direction and engage full throttle again. But it would not move out of the direction it was going in. If I was facing towards home with full forward or reverse throttle, the horizontal speed changed by a very small amount. I then assumed that the controls were doing nothing. But was confused as I could adjust the altitude. I hit the controls in all directions.  I don’t really know what was happening by this point, I thought it could have been wind but then it didn't matter what I was doing, which way I was facing, the speed was a constant. I left the DJI GO app to look on google about Fly Away drones but without any success. Then re opened the app. Put it to (I was meant to hit RTH but was panicking by this point) it went into landing mode aagin and the drone stopped moving away. It went from moving away at 26kph with full throttle engaged (opposite to movement direction- forward throttle towards me/home point), to speeds around 0kph. And then it just descended slowly on the same spot as expected. I then hit full throttle again and it started moving back towards home. By this point I was so far away and had no battery to fly back with. Even when flying back towards the home point, it was turning quite violently and was definitely not how it normally would fly.

It then ran out of battery and then crashed on the side of an inaccessible cliff.

Having reviewed the flight log myself I can see the following:

After the battery overload error message: 2 mins 08 seconds,  no controls being touched - H:28m D389m - 2 mins 18 seconds  H: 21m D:440

So it travelled 51 metres in those 10 seconds with no control operations.

That works out that it was travelling around at 5.1 metres per second. That’s 18.7 kph/ 11.6mph.

Wind reading data from the flight logs show the following : Point C=8.19 mph, FT - 1min29s, Point D:13.76mph, 1min37s Point E: 15.57mph FT= 3mins37s. The wind readouts from happy drones later were at 32mph at 7mins and 51mph at 10 mins! Those are obviously insane wind speeds and I wouldn't have flown the drone in anything like thos conditions. Tasmania was windy this month but forecasts showed ground wind of 10-15mph. That can obviously increase dramataically as the allititude increases. I'd spent hours looking into what winds the Mavic could handle before online. Videos of it hovering and flying pretty comfortably at 30+mph winds. Some reports are much higher as well. DJI advises not to fly in winds over 22mph and you'd expect them to have a huge window of what it's capable of and what would be deemed safe wind speeds. I had done 2 very short flights the previous day to see for myself how it handled in the wind and I was impressed.

There's just a few thigns that don't make sense to me.

1. Why aren't compass errors shown on screen during flight but are in the flight records?
2. How strong would winds need to be to make it drift away as fast as 11.6 mph?
3. The roll angle showed at 18 degrees at the time of that difrt away. Can this roll figure be used to figure out the math of the wind speed?
4. Why did the speed remeain the same with or without full throttle engaged?
5. Why in landing mode did the horizontal speed come to a half before it started to descend?

Here are the flight logs from happy drones and phantom help:

https://app.airdata.com/main?flight=9c881da025e66944bcd41b427a1a14a4&page_id=GENERAL


http://www.phantomhelp.com/LogViewer/4N2C1GAXZYW105UOLVJG/


Any insight on this as the DJI analysis team came back with an incredibly vague response. On first glance, it does look like wind. But there's so much that doesn't add up on this..


Thanks in advance if you've read this far

I think you may have to accept that the wind speed and gusts played a significant part in all of this. Most people have no idea just how the wind can change once you go higher and certainly around cliffs, there can be extreme wind conditions.
The compass warnings probably flashed on the screen but they may have only been there briefly.
Your main mistake was flying downwind to start with. If you had flown into wind then you would have had a tailwind to go home.
I think you may have to jot this one down as a hard lesson learned.

Sorry for the crash, could you please provide me with your case number? I'd like to check it for you.

Did you flick it into sport mode at all, I have been in a very similar situation and that really saved my arse! I have a sticker on the RC to remind me of SPORT = EMERGENCY. Sorry you lost it, what a bummer! Sport mode makes a massive difference in wind.

Wow, complicated situation. I hope data analysis will help see what happened.

Spot mode can only help up to a point, depending on the wind speed. Mine was lost, even after I switched to Spot, it was still going backward between 0 and 12 kph, dragged out by seaward wind.  The only consolations was, I hadctime to say goodbye, as it drops into the waves, I had the final moment captured!!!  

I've looked at your log and I'd have to agree with Jenee that this appears to be an example of flying in winds that are too strong. Specifically, the winds were out of the NNE at around 35 KPH, which is right around the limit of what the Mavic can handle when it's not in Sport mode. I noticed too that early in the flight (2:06.6) you got a "Battery: Overcurrent during discharge" warning, which is consistent with the Mavic trying to fight a strong wind.

After that it just continues to be pushed south by the wind, though you may have noticed that as your altitude decreased that you did have some limited success in bringing it back towards you, which is because the wind tends to be less at lower altitudes. And yes, as TroutboyNZ indicated, there's a good chance that the extra speed boost provided by Sport mode would have been enough to prevent the loss, but unfortunately that didn't happen.

Anyway, I'm sorry that you lost your Mavic, but hopefully these replies provide some degree of confidence that DJI's assessment was appropriate even if they didn't communicate very effectively.

sorry to hear bout your Mavic

Sorry to hear and thats no good.

Before I fly, I usually look at this app UAV Forecast, tells you whether it's good to fly or not.

• Tells you the weather, Wind Chill, Wind and Wind Gust... and a bunch of other stuff like Kp index that can stuff up the compass.
  

If none are green, I usually keep my drone on the ground.

A week ago, I decided to take my Mavic out for a spin, checked the app, said everything looks good. Long story short, got to this hill and checked the app again, says not good to fly, winds at 45kmph (28mph) and wind gust at 50kmph. If I'm correct, the Mavic runs at max speed 45kmph and 60kmph at sports mode.

Given it was a wide empty area, I decided to fly anyways.

• Got the Mavic up to 100 meters, got a few of those wind velocity warnings, but it moved fine.
• All of a sudden when I was moving the mavic back towards me, it was moving really really slow, sometimes doesn't look like its moving at all.
• Yes there was some drift as well, but it's expected with the high winds.
• At that point I realised I was flying against the wind, so I lowered the Mavic to 50 meters and returned safely.
  

What I'm trying to say is that, wind plays a big part. Yes there are videos of people blowing the Mavic with a leaf blower, but that is just a narrow one directionaly blow and it's very different in the open air.


With the rest of your questions regarding battery error, etc, not sure I can chime in, wll let the experts drop in their 2 cents.

This brings up an interesting question.  I haven't tried it, so don't know the answer to this question.  Let's say the Mavic is limited to 30mph forward speed.  If you fly it full bore into a 30mph head wind, it will zero out standing still.  But, if you fly it downwind full throttle, will it limit to 30mph or will it go to 60mph?  If it is limited to the 30mph theoretical limit I set for this example, that might explain some of the shenanigans with not obeying the controllers commands.

DJI Diana Posted at 2017-10-16 00:30
Sorry for the crash, could you please provide me with your case number? I'd like to check it for you.

The case number is CAS-1096934-Z1W8H7 CRM:0056000000659

Thanks for looking

Thanks for your input everyone.

It's a pretty unique set of circumstances on this. The Mavic does move away in line with the wind direction. I was looking at trying to prove what happened as if it was wind and if it wasn't. There's a few things that didn't make sense to me when proving it was wind on this. One is the speed it moved away from me. It was a constant regardless if full throttle was engaged or not. The wind read outs around the time of the flyaway were well under what the Mavic manual recommends so I'm curious how accurate those readings would be in the flight records and if there's a way to figure out how the on board system gets those numbers, looking at the pitch/roll to get that wind read out manually.

The other point which I don't understand is that it's moving away at speed and then I triggered Landing Mode. This brought the bird from flying away at 30kph with full forward throttle engaged to a stop, and it did so before it started to descend.

In hindsight I really wish I had dropped the altitude significantly as soon as possible so I could then see if that would have made a difference. My thinking was that I saw a battery overload message on my screen and because I had a battery cell error on my p4 a year earlier where it fell from 270ft instantly, I was expecting the same and wanted to get it back as soon as possible, I wanted to get the bird back in my line of sight so dropping it against the ocean and rocky cliffs rather than a white cloudy sky would have made it more difficult. You know what they say about hindsight anyway!

I also think had I not read so many fly away stories, that my p4 didn't fall out of the sky for no reason the previous year, the subsequent headache of trying to get that sorted with DJI and it getting stuck in Myanmar due to the strict postage regulations there and the battery over charge notification during this crash flight, I might have responded differently and it would be easier to eliminate reasons for it moving away. I was convinced at the time this wasn't wind doing it as I had it in my line of sight and it wasn't really struggling at all. I knew the weather report for the time and had tested it myself in higher winds + seen multiple videos of people flying it in 40+mph winds (which I wouldn't have attempted myself).

I'm two drones down now, the P4 had 6 hours flight time and this Mavic just 2 hours. As the P4 crash clearly wasn't my fault, I just want to be sure what's going on here. This is my job and I really do look after my gear.  I've just had such a painful experience with DJI so far with the last year trying to sort my p4 with such poor communication for the CX team (I've never dealt with a company that doesn't allow managers to speak to customers?!).

And final point, the compass error notification on the flight record did not flash up on my screen. When you play review the flight on my phone, all other errors/tips/info shows. I've also looked back at other flights after I updated my Mavic and there are Compass Error warnings everywhere! All of which didn't show whilst flying. Being that I don't trust the products and I'm overly cautious after the P4 incident, that warning error would have stopped me flying on this crash flight until I figured out what had happened. I'd watched many videos with the Compass Error where people had lost all control of the drone so I definitely would have ended the flight instantly and that warning should have been shown to me after 7 seconds. It's not going to make a blind bit of difference moving forward with this but maybe DJI should address that issue for other pilots as I think most of us would like to know when there's a problem with something?

I've just this minute had another vague response from DJi. ''At first, sorry for that we couldn't judge the performance from other unofficial data, application or Message. And secondly, the drone was interfered by the large winds, our app reminded you many times that the high wind velocity, please ensure the aircraft stay with your line of sight. And during the flight, the app prompted was “overcurrent” not any error message, due to the aircraft was blown by the winds and the motor output was over than the normal situation, so the current would become bigger. In the end, the aircraft was blown by winds and against with it all the time, even though you didn't operate the remote, with no input, the drone would be easily to drift in the air because of the high winds''.

I did request detail into what wind speeds the Mavic will fly drift as fast as it did in. And wanted some insight into what I've written above with the auto landing bringing it to a stop. But it's easier to reply with a somewhat impersonal and scripted response to just say it was the wind without any further explanation in addressing my concerns. And I only had one high wind warning before it was too late. A warning which I was getting in the lightest of breezes on previous flights. And also, it wasn't out of my line of sight, I told them this as well.

Pretty gutting to lose this much money with two different products. Drones aren't for me it seems

And to add to their response, In my mind with the wind readings from 'unofficial data' I have (healthy drones/phantom help), it shows wind speeds lower than their advised flying speeds. So surely you have thought if they wanted me accept it was in fact extreme winds, that it was pilot error and to get me to buy another drone from them, they'd give a bit more detail to show how fast the winds would have to be for it to fly away like it did. And further address my other concerns about that flight. It just comes across in dealing with DJI that they don't care about the individual customer as they have such a high percentage of this market. There's literally no point me responding to their latest email because I'll just get more of the same.