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Signal lost and fail to RTH, crashed near 1400m away

malume

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RC signal lost about 2 km away in an open area, I don't know why the signal was lost but when it recovered, the MP seems move very slow ( 2-3 m/s) to return home, even I tried to speed up.
Then finally the battery is dying and it began to land?? on water?? I saw the MP is declining.

I tried my best to fly it near the water where I would be able to find it later.
However, the signal lost again and the last recored signal was at 30 m.
I then try my best to locate the drone on map and finally I found it with 2 propellers broken and one is missing. I posted a picture when I found it.
The gimbal is not working now and may I ask if it is my fault or DJI's malfunction?
This link is what I got from healthydrone.com. Is there anyone can help me to figure out who's fault?
Airdata UAV - Flight Data Analysis for Drones
Thanks all !
 

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I'm not a pro at reading the logs, but how windy was it? If you have to use Sport to overcome winds and the battery hits critical, it's landing, like it or not.

That said, if it does land, it should land and not crash...that looks like it crashed to me. Of course it has to land flat, on a not flat surface, one set of props will hit and flip it over or something.
 
I'm not a pro at reading the logs, but how windy was it? If you have to use Sport to overcome winds and the battery hits critical, it's landing, like it or not.

That said, if it does land, it should land and not crash...that looks like it crashed to me. Of course it has to land flat, on a not flat surface, one set of props will hit and flip it over or something.

I don't know the wind speed but I think it is moderate. the problem is the signal was lost and I did't know what was happened. Even my SD was not successfully recording the moment of crash. I guess it is the battery is low and MP stop recording automatically.
 
Ouch.. Did you see the size of the chip taken out of the rock on the bottom right of your photo?!?! Blade must of hit it hard to break that off :)

Were you using RTH when you pushed on the stick to make it go faster? I find that RTH is a lot slower than if manually flying it. I have been in a few spots where battery was getting low and RTH fly's slow, usually because of High winds, then I put it into sport mode and just fly back manually. And thankfully made it back every time so far!

Maybe it landed perfectly but a train hit it afterwards? Unlikely.
 
If you want us to look more closely, tick the allow kml and csv download in your AIRDATA sharing settings for the flight.
Bad luck about the prang. Lucky a train did not come along!

upload_2017-4-9_10-36-7.png
 
Looks the signal loss was due to the hill on the bend in the river where the sports field is.

upload_2017-4-9_11-23-52.png

Log shows you were flying away from home SE pretty much flat out at ~ 42mph when you had signal loss. Whereas at the start of the flight (also in sports mode) when you headed the other way along the river, you only ever briefly achieved 30mph heading NW and for the most part were only achieving ~25mph.
Therefore it looks to me like you had to return to home into a very strong headwind. I would have though you would have been able to achieve a higher speed returning to home though. I am wondering if you had toggled the mode switch from S to P and back to S again, or simply cancel RTH, if it would have switched out of GoHome state and given you the ability to fly faster.
 
Looks the signal loss was due to the hill on the bend in the river where the sports field is.

View attachment 10236

Log shows you were flying away from home SE pretty much flat out at ~ 42mph when you had signal loss. Whereas at the start of the flight (also in sports mode) when you headed the other way along the river, you only ever briefly achieved 30mph heading NW and for the most part were only achieving ~25mph.
Therefore it looks to me like you had to return to home into a very strong headwind. I would have though you would have been able to achieve a higher speed returning to home though. I am wondering if you had toggled the mode switch from S to P and back to S again, or simply cancel RTH, if it would have switched out of GoHome state and given you the ability to fly faster.

Thanks for your analysis. I had partially or no signal over a couple of mins and tried everything (maybe not smart) to achieve the signal back until the last moment before landing, I saw the battery was about 11% and height is 30m. I realized it is impossible to RTH and I tried to land safely but have no control if the MP. Those part I couldn't see from my SD card.
 
RC signal lost about 2 km away in an open area, I don't know why the signal was lost but when it recovered, the MP seems move very slow ( 2-3 m/s) to return home, even I tried to speed up.
Then finally the battery is dying and it began to land?? on water?? I saw the MP is declining.

I tried my best to fly it near the water where I would be able to find it later.
However, the signal lost again and the last recored signal was at 30 m.
I then try my best to locate the drone on map and finally I found it with 2 propellers broken and one is missing. I posted a picture when I found it.
The gimbal is not working now and may I ask if it is my fault or DJI's malfunction?
This link is what I got from healthydrone.com. Is there anyone can help me to figure out who's fault?
Airdata UAV - Flight Data Analysis for Drones
Thanks all !
I can analyze your flight, but AirData is limited. Can you upload the original TXT, or better the DAT from the Mavic itself?
 
.. further to my earlier.
Your initial signal loss lasted ~ 2min 10 seconds. Upon reconnect drone had commenced RTH and was coming back (into wind) at ~11mph. Over the next 15seconds it slowed to about 5mph probably due to a gust. At this point first user input in, Full forward elevator to speed up. This had little to no effect, most probably because mavic was already at the nose down pitch limit. For about the next three minutes it flew along in RTH mode with full nose down elevator most of the time and small amounts of aileron causing the path to zigzag a bit. Unfortunately full nose down elevator had little effect in increasing the speed, until towards the end, when it increased briefly to 16mph and then dropped back to 11mph. Changing wind strength I suspect.

Then at 290 feet atlitude and 13% battery, Critical battery auto-land commenced. Aileron input to slew across toward river bank.15 seconds after this, while on forced descent first rudder input to turn, ~ 90 degrees to right to spot landing beside River. (nice Move). As full forward pitch was also still being applied and heading path was now crosswind and downwind again, speeds up to 24 mph were achieved. 10 sec prior to end of recording stick released one would assume because in OK spot to land. signal loss at 110 feet.

Here is a better image of the last part. You can see the first straight part of the RTH. Then path starts to wiggle once full elevator and small amounts of aileron are added.
upload_2017-4-9_20-50-53.png

the Mavic never left Return to Home mode until Autoland commenced. Mode swtich was in Sport. Had RTH been cancelled and Sports mode become active, increased pitch and therefore speed should have become available

As @Cyberpower678 mentioned the original TXT file from the app or the DAT from aircraft will reveal more if you are interested. It would confirm you were at the pitch limit and so on. But really I would say you were defeated by the strong wind.

Simplest way to get the text file is download it from Airdata and then post the files.

upload_2017-4-9_21-0-49.png
 

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Im not saying this was the case here but hills/trees/structures are often underestimated. Terrain that's 30m higher and 1000m away from homepoint requires you to be at 150m altitude if you continue that path at 5km distance provided there are no trees/structures additionally. Also sports mode does save the day if you need to fight wind. I spoke to someone complaining the mavic had a hard time fighting the wind but did not realize that having OA on reduces speed in P-mode.
 
.. further to my earlier.
Your initial signal loss lasted ~ 2min 10 seconds. Upon reconnect drone had commenced RTH and was coming back (into wind) at ~11mph. Over the next 15seconds it slowed to about 5mph probably due to a gust. At this point first user input in, Full forward elevator to speed up. This had little to no effect, most probably because mavic was already at the nose down pitch limit. For about the next three minutes it flew along in RTH mode with full nose down elevator most of the time and small amounts of aileron causing the path to zigzag a bit. Unfortunately full nose down elevator had little effect in increasing the speed, until towards the end, when it increased briefly to 16mph and then dropped back to 11mph. Changing wind strength I suspect.

Then at 290 feet atlitude and 13% battery, Critical battery auto-land commenced. Aileron input to slew across toward river bank.15 seconds after this, while on forced descent first rudder input to turn, ~ 90 degrees to right to spot landing beside River. (nice Move). As full forward pitch was also still being applied and heading path was now crosswind and downwind again, speeds up to 24 mph were achieved. 10 sec prior to end of recording stick released one would assume because in OK spot to land. signal loss at 110 feet.

Here is a better image of the last part. You can see the first straight part of the RTH. Then path starts to wiggle once full elevator and small amounts of aileron are added.
View attachment 10257

the Mavic never left Return to Home mode until Autoland commenced. Mode swtich was in Sport. Had RTH been cancelled and Sports mode become active, increased pitch and therefore speed should have become available

As @Cyberpower678 mentioned the original TXT file from the app or the DAT from aircraft will reveal more if you are interested. It would confirm you were at the pitch limit and so on. But really I would say you were defeated by the strong wind.

Simplest way to get the text file is download it from Airdata and then post the files.

View attachment 10258
Actually no. The txt file you get from Airdata is not useful at all. It's not the original and it will not work with flight analyzer software.
 
Actually no. The txt file you get from Airdata is not useful at all. It's not the original and it will not work with flight analyzer software.
Actually YES, the TXT file downloaded from airdata is very useful and will open just fine in CsvView. It is the original flight log sent from the mobile device that was created by DJIGo, with the only change being the file name schema. Give it a crack and you will see.
Perhaps you are confusing it with the Airdata CSV, which you obviously have not been able to open in airdata and analyse using you preferred methodology.
 
This is why you should be flying only when you have sight of your drone. The technology isn't there yet for such autonomy. I don't trust my Mavic to navigate around buildings or to fight unexpectedly strong winds from 1000m away. The Mavic cannot currently factor in headwind or tailwind for the RTH calculations so don't trust it too much to deal with mother nature flawlessly.
 
Actually YES, the TXT file downloaded from airdata is very useful and will open just fine in CsvView. It is the original flight log sent from the mobile device that was created by DJIGo, with the only change being the file name schema. Give it a crack and you will see.
Perhaps you are confusing it with the Airdata CSV, which you obviously have not been able to open in airdata and analyse using you preferred methodology.
No. It was the TXT and the data in it was not the same as the original. The RC stick control values are all different. @msinger can confirm this.
 
That might be the case, but is certainly opens just fine in CsvView and there is plenty of useful information in there. Are you saying all the pitch roll and yaw values are wrong too and dreamt up along with all the other labels?
 
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That might be the case, but is certainly opens just fine in CsvView and there is plenty of useful information in there. Are you saying all the pitch roll and yaw values are wrong too and dreamt up along with all the other labels?
They're not dreamt up, but just changed to different ranges and it completely throws me off, since I'm used to different values. Sure it opens in CsvView, but the log is altered and it actually drops useful data to look at since AD doesn't use it. Maybe they've changed it since I last checked, but I'd rather just look at the original TXT from the user.
 
No. It was the TXT and the data in it was not the same as the original. The RC stick control values are all different. @msinger can confirm this.
The "Download Original" link will allow the original TXT flight log to be downloaded. That link only appears if you have an HD 360 Gold or better account though.
 
The "Download Original" link will allow the original TXT flight log to be downloaded. That link only appears if you have an HD 360 Gold or better account though.
Oh dear, maybe I did screw up on this one. I apologize @Logger. I'm sometimes thickheaded.
 
Edit...
No worries all good. We are on the same page now.
 
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