The theme speaks for itself.

Just want to say that after purchasing the drone I have flown about 23 km and everything was fine On the penultimate day of my trip to Vietnam and Malaysia I was in the city Dalat. For the filming of this province it was chosen one of the highest points in the area Pinhatt mountain. It is just a plateau with a radius of 40 meters at an altitude of about 1650m comfortable enough for take-off platform without signal interference. Here you can find some of the most impressive places to enjoy landscapes of Dalat ( https://turavietnam.com/the-7-best-viewpoints-in-dalat/). For the completeness of the shooting I was doing a flyby of the area to the North of the home piont. 14.01.2017 at 2 pm I started the flight with full battery and pre-take-off, despite automatic setting point home, I have established the point of return home for 100m ( this is above all the trees in this area including the highest point of the takeoff). Flying somewhere 1 km I started the return with a small decline to shoot a few mountain ranges below. I did not make sharp cuts, and in General kept shooting very smoothly for cine pictures. But link was beginning to crash quite dramatically and I could not return the drone to a height to restore the connection. Need I say, that the loss of connection has happened to me often in Kuala Lumpur because of the high skyscrapers and I've always managed to return the Quad in the signal area. But in this case it hung and didn't listen to taps on the sticks of the remote control - last I saw on the screen is the trees following the course home. I tried to run in the Eastern part of the "Pinhatt" plateau in order to try to find a signal. It didn't help I tried going down to 100 meters below the plateau, which also gave no result. I decided to wait for a drone waiting to begin the automatic return to home. However, this did not happen!!! I was very frightened precarious situation, and wrote into the channel a telegram the community of fans of drones to help in further action. I was recommended to go to the last known coordinates without turning off the remote control. Taking into consideration that the area was mountainous, dominated by coniferous trees and tropical jungle in the lowlands, the way to the point took about an hour and a half. Unfortunately near the point coordinates to get the connection also failed. I was looking for the drone to full discharge control in the jungle and it took about 4 hours. More to continue the search I could not as it was getting dark. Overall this was a great risk, as it was not a single soul in this district and it was a wild forest. Despite this the next day I made a second attempt to search as half of the videos is on the SD card in the device. Here I have decided to record the route search: https://ru.wikiloc.com/wikiloc/view.do?id=22049768 . More than two-hour search gave no result. In the end, I lost two days of vacation in the jungle in search of the drone, which did not return to normal mode at the place in your home. I did everything I could in order to avoid the loss of the aircraft and never made a mistake in piloting. I am very upset by losing my drone and a very important videos (there is of course my fault to transfer it to laptop, but I didn't plan to lose the device). I believe that this is the fault of a software failure of the device. Here you can see the log of the flight and make sure there are no errors, piloting and environmental impact: http://app.airdata.com/main?share=GGPauj

I sent this email to the support. They responded quickly by asking associated questions for the registration of the support request. Then just disappeared and didn't respond for 3 days. Is this normal? How long usually need to wait response from DJI?

Wow. I'm sorry to hear about losing your drone. Interesting. Did you enable the "Return to Home" option if it was low on battery or if it lost remote control signal in the DJI Go 4 app?

Sorry for your loss.

It is strange that the mavic changed mode to wifi. Here the problem started.

For more details, please upload the flight log file here  http://www.phantomhelp.com/LogViewer/Upload/

Agent Sgt. Shad Posted at 2018-1-23 12:08
Wow. I'm sorry to hear about losing your drone. Interesting. Did you enable the "Return to Home" option if it was low on battery or if it lost remote control signal in the DJI Go 4 app?

I did not turn on the RTH mode manually, and I could not turn it on, since there was no connection with the drone. Although, to be honest, I stitched both the return button and the stick, a few minutes after the loss of communication. But it did not make sense without communication. I just waited for him to start the return procedure as usual after losing communication. In any case, there is still 79% of the battery was.

Ahmed Hussain Posted at 2018-1-23 12:23
For more details, please upload the flight log file here  http://www.phantomhelp.com/LogViewer/Upload/

Done:
http://www.phantomhelp.com/LogViewer/BZAT8TIE6B4I6I35S8RX/

thanks for help

MagSky Posted at 2018-1-23 13:11
I did not turn on the RTH mode manually, and I could not turn it on, since there was no connection with the drone. Although, to be honest, I stitched both the return button and the stick, a few minutes after the loss of communication. But it did not make sense without communication. I just waited for him to start the return procedure as usual after losing communication. In any case, there is still 79% of the battery was.

Maybe that was why you lost your drone for good. If you went on your trip and turned on RTH before, it would of come back home. Like, you were at home, and you manually turned on RTH first and left it on. That's what I do. I enable it and I don't turn it off. Also, that's a reminder for other people. When you first fly, always make sure to turn it on. It'll be on for the rest of eternity unless you turn it off.

Agent Sgt. Shad Posted at 2018-1-23 13:32
Maybe that was why you lost your drone for good. If you went on your trip and turned on RTH before, it would of come back home. Like, you were at home, and you manually turned on RTH first and left it on. That's what I do. I enable it and I don't turn it off. Also, that's a reminder for other people. When you first fly, always make sure to turn it on. It'll be on for the rest of eternity unless you turn it off.

So, in a nutshell, you didn't turn on RTH before you flew and it didn't return. Maybe that's what happened?

During the flight there was nothing abnormal except at the last seconds when your mavic changed to wifi mode then landed over the trees near the last coordinates.

Agent Sgt. Shad Posted at 2018-1-23 13:41
So, in a nutshell, you didn't turn on RTH before you flew and it didn't return. Maybe that's what happened?

I think the OP mean't he couldn't activate the RTH button because he had already lost communication with his drone.

Here is the answer to your problem:
1. The drone was behind the mountain
2. Because of that, you got signal loss.
3. The drone probably started RTH and crashed into the side  if there were trees in the way while it was climbing

Calculating Viewshed from your starting point, your flight was in the radio shadow area. Green on the map shows where you had radio coverage from your take off point.

HP was set twice at takeoff.

I'd suggest looking for your drone on the slopes along the plotted yellow line between the last signal location and your home point. Especially the places, where the yellow line intersects with the terrain.

Simmo1 Posted at 2018-1-23 15:23
HP was set twice at takeoff.

They were, but both times at the top, near the take-off point, with only 20m between the two sets.

Ex Machina Posted at 2018-1-23 15:10
I think the OP mean't he couldn't activate the RTH button because he had already lost communication with his drone.

I know. What I meant was that he didn't turn of RTH before he did his flight.

BumblerBee Posted at 2018-1-23 15:18
Here is the answer to your problem:
1. The drone was behind the mountain
2. Because of that, you got signal loss.

That can be a possibility as well. Good thinking!

BumblerBee Posted at 2018-1-23 15:18
Here is the answer to your problem:
1. The drone was behind the mountain
2. Because of that, you got signal loss.

About #3. It will first go to set RTH altitude and then go home as it was lower than RTH altitude.
The real question is was it set to RTH , Hover or Land. When signal is lost it was just hovering with 79% battery left.

Hey MagSky, I'm sorry to read the accident. Could you tell us your case number or ticket number here? I'd like to check the exact status and try our best to help.

Agent Sgt. Shad Posted at 2018-1-23 13:41
So, in a nutshell, you didn't turn on RTH before you flew and it didn't return. Maybe that's what happened?

Sorry, read the logs, I have set the home point before flight. When I talked about RTH I was talking about the start of the return process and not the setting home point. So for me it is not clear why he has not started to return.

BumblerBee Posted at 2018-1-23 15:18
Here is the answer to your problem:
1. The drone was behind the mountain
2. Because of that, you got signal loss.

1. Ok.
2. Ok This is something that happens often, I would not say that there was a shotgun behind the mountains. From the highest point seemed to be that this is simply an crest with trees ( through which the signal pass).
3. Why it crashed? I set the RTH high above all the trees within a radius of 80 km.

G_Sig Posted at 2018-1-23 16:14
About #3. It will first go to set RTH altitude and then go home as it was lower than RTH altitude.
The real question is was it set to RTH , Hover or Land. When signal is lost it was just hovering with 79% battery left.

I never changed RTH options.
It's stupid to change the RTH setting in the jungle and to choose the spacious place to take-off, Having a goal to return the drone to that location. Also it's stupid to change the settings flying 1 km in FPV mode. I specifically expect from the drone in these conditions, the return to home of another is not assumed.

BumblerBee Posted at 2018-1-23 15:26
I'd suggest looking for your drone on the slopes along the plotted yellow line between the last signal location and your home point. Especially the places, where the yellow line intersects with the terrain.

Why such a proposal? I'd like to understand how he could be there. Unfortunately I am no longer in Vietnam. It would of course tried. Maybe my friends who stayed in the vacation will go away and try at this point to look for. Can you send the coordinates on the map?

MagSky Posted at 2018-1-23 22:21
Why such a proposal? I'd like to understand how he could be there. Unfortunately I am no longer in Vietnam. It would of course tried. Maybe my friends who stayed in the vacation will go away and try at this point to look for. Can you send the coordinates on the map?

I don't really agree with the explanation that was offered for the loss, though admittedly I don't have a better one. I do agree that the cause of the disconnection was a combination of distance and loss of line of sight, but there's nothing in the log to suggest that your Mavic was below the tree line at that time and would have hit something when it ascended.

Shortly after the disconnection occurred it should have ascended to the RTH height, which -- as you pointed out -- was a healthy 100m above your takeoff location. That should have been a very safe height, because the home point / takeoff location was at the top of a hill that appears to be about the highest point in that area, so your effective RTH height should have been more than adequate for a safe RTH. Then again, if it had ascended to 100m above the takeoff height when the disconnect occurred then you should have almost immediately regained the connection, but as best I can tell that didn't happen.

One concern I do have is that even if it had attempted to RTH that the wind at 100m above the top of that hill might have been too strong for it to make it back successfully, but again, that doesn't really explain what happened because even if it couldn't return you should have still been able to reconnect with it when it ascended.

Since I can't really explain what happened based on the TXT file, the only other thing I can suggest is to retrieve the DAT file(s) off your tablet, upload them to DropBox, and provide a link here. The instructions for accessing them are here.

DroneFlying Posted at 2018-1-24 03:58
I don't really agree with the explanation that was offered for the loss, though admittedly I don't have a better one. I do agree that the cause of the disconnection was a combination of distance and loss of line of sight, but there's nothing in the log to suggest that your Mavic was below the tree line at that time and would have hit something when it ascended.

Shortly after the disconnection occurred it should have ascended to the RTH height, which -- as you pointed out -- was a healthy 100m above your takeoff location. That should have been a very safe height, because the home point / takeoff location was at the top of a hill that appears to be about the highest point in that area, so your effective RTH height should have been more than adequate for a safe RTH. Then again, if it had ascended to 100m above the takeoff height when the disconnect occurred then you should have almost immediately regained the connection, but as best I can tell that didn't happen.

Totally agree with you! The drone was supposed to start taking off to the RTH altitude, and I would reconnect with the drone again. But that did not happen.
The weather that day was beautiful and windless and I think if the wind was not at 1660 m. then it would not have been on 1760.

Returning to your request - how safe is it to upload DAT files? what do they contain?

If you look at the 3D flight path that I posted from GoogleEarth, you'll see that you descended quite a bit, to the point of being right above ground/tree line. (The short red line is where you had your last reported signal loss and re-aquisition)
The last entry before the final loss of signal shows the drown plowing into the side of the hill. Even taking some error in altitudes on GE's part, that was still low.

If Mavic ended up under the canopy of some tree after it lost the signal and continued to fly forward for a short while, it would then not be able to rise to the RTH altitude, crashing.

As for the coordinates, there are in the log, the last even recorded at:
            <coordinates>108.42973647,11.86943556,1548.7546143</coordinates>

BumblerBee Posted at 2018-1-24 10:27
If you look at the 3D flight path that I posted from GoogleEarth, you'll see that you descended quite a bit, to the point of being right above ground/tree line. (The short red line is where you had your last reported signal loss and re-aquisition)
The last entry before the final loss of signal shows the drown plowing into the side of the hill. Even taking some error in altitudes on GE's part, that was still low.

I was not too low until the nearest trees were 15-20 meters down and 50 meters ahead. I definitely remember that. So he could not be under any tree under my control. This is out of the question.

The last entries in the log (after the last download link restore) indicate that the AC had no stick input and had, in fact,  stopped moving.  There is no indication (from VPS height) that the AC was near ground level.  That, however, does not mean there weren't obstructions above.  Like several others, I feel that if RTH was initiated following loss of connection, AND the AC was able to ascend to RTH altitude, then there should have been a re-connection to the RC.  

The other comment I would make is that a downlink failure is on the RC receiving end and doesn't mean that the AC cannot receive commands from the controller.  My thinking is that the transmitter in the controller may be a bit more powerful than that of the Mavic.   So I'm wondering if OP actually initiated an RTH or just assumed RTH following loss of downlink.   RTH would eventually happen anyway if  the Mavic could not receive telemetry from the controller or the controller was turned off or the battery life reached a critical point (my understanding  with regard to this situation is that the Mavic just lands).

Having been to Vietnam recently, I can appreciate the difficulties of treking off trails.  Still, Find-My-Drone may have been the best recourse.

MagSky Posted at 2018-1-24 09:08
Totally agree with you! The drone was supposed to start taking off to the RTH altitude, and I would reconnect with the drone again. But that did not happen.
The weather that day was beautiful and windless and I think if the wind was not at 1660 m. then it would not have been on 1760.

how safe is it to upload DAT files? what do they contain?

I'm not sure what you mean by "safe", but I can't think of any way that it's more risky than uploading a TXT file. It has mostly the same data as the TXT file, but it won't stop where the TXT file did, and you should be sure to upload all the ones from around the time of the last flight.

Frankly, I think it takes a somewhat fanciful leap of imagination to suggest that your last position happened to be under a tree in a dense forest without either OA or VPS registering anything nearby before that, so I'm inclined to believe your account that you were well above the canopy. And even if we assume that Google Earth has perfect precision -- which it doesn't -- there's also the fact that any height / altitude value produced by the Mavic is only an estimate that's often significantly different from reality.

DroneFlying Posted at 2018-1-24 13:56
how safe is it to upload DAT files? what do they contain?

I'm not sure what you mean by "safe", but I can't think of any way that it's more risky than uploading a TXT file. It has mostly the same data as the TXT file, but it won't stop where the TXT file did, and you should be sure to upload all the ones from around the time of the last flight.

Here it is.
https://drive.google.com/file/d/ ... w0/view?usp=sharing
In General, DJI told me that they can't figure out what was the loss and they can only offer 30% discount on a new product. This is absolutely unacceptable. Later articulate why.

DroneFlying Posted at 2018-1-24 13:56
how safe is it to upload DAT files? what do they contain?

I'm not sure what you mean by "safe", but I can't think of any way that it's more risky than uploading a TXT file. It has mostly the same data as the TXT file, but it won't stop where the TXT file did, and you should be sure to upload all the ones from around the time of the last flight.

Are there any news?