Hello everyone!
Who could help me to investigate WHAT HAPPENED and why my drone hasn't returned to the HM after i lost signal with RC
1. I was at the Maragogi beach in Brazil (no antenas, only pure nature and one hotel)
2. I had Home Point with the altitude to return 99m
3. On the 17th minute of the flight my drone has lost signal with the RC (for the first time in my life )
4. I have experience with drones it was my 199th flight with DJI... but...

The drone was supposed to return but he hasn't done ANYTHING (we found him exactly where the last GPS location was)

1. He was just 225 meters far from me and 160m of altitude.
2. The wind wan't strong. Weather conditions was perfect.
3. He had 25% of the battery! That was enough to come back to the Home Point  2 times because he was really close to me

DJI please check my materials

The video of the flight log with my sticks movements on youtube is here  


We went to the beach when the tide was low and found my Air 2 in the ocean at night exactly where the last GPS location was. Video how we found him at night.  
I assume that AIR 2 just didn't do anything but he had Home Point and had to return to it...

So now my drone is DEAD after 12h in salty water but I found SD Card and it is alive!
There are fotos, videos and some data that you could be interested in to take a look.

Dear DJI. How to investigate what happened?  
Why drone hasn't returned althought he was so close to me and had HP?
Could you help me to find the reason of this drone crash?

Hi there. Thank you for reaching out and we're sorry for the incident that happened on the unit. I'm afraid that you may consider sending the unit in for a proper diagnosis. You can contact our support team to start up a ticket at https://www.dji.com/support . Also, the warranty can be applied depending on the outcome of the damage assessment including the warranty period of your unit. Thank you for your understanding and support.

Hi there, we are sorry to know about the accident. You can submit a case through the link below. If there is a doubt about the accident, data analysis can also be applied as long as the drone is within the warranty period. http://www.dji.com/support

Go to the webpage
https://www.phantomhelp.com/logviewer/upload/
read the instructions lower down that webpage, retrieve the flight log, upload it to that website and post the resulting URL here.

Sean-bumble-bee Posted at 4-20 22:16
Go to the webpage
https://www.phantomhelp.com/logviewer/upload/
read the instructions lower down that webpage, retrieve the flight log, upload it to that website and post the resulting URL here.

Thank you! I tried!  I uploaded my flight log here

https://www.phantomhelp.com/LogViewer/5HAGGFLEFX7IF4650UUW

https://www.phantomhelp.com/LogViewer/5HAGGFLEFX7IF4650UUW  COPE THAT LINK. I don't know why that link is not working when you click in it. But the link works.

How to send here KLM file CSV file or Flight Log TXT? Can see everything on the link that i sent you?

Seems that everything was fine... Just this error...

Image transmission signal min be blocked. Position remote controller to face aircraft and adjust antennas for optimal signal strength or fly at higher altitude (Code: 80004).; Weak signal. Adjust antennas.; Image transmission signal may be blocked. Position remote controller to face aircraft and adjust antennas for optimal signal strength or fly at higher altitude.

And he didn't return although had Home Point, Air 2 was really close to me and everything seems to be fine.

People can access the information they will want from that page so I wouldn't worry about the kml.

I am not certain that I am interpreting the csv correctly but what gives me cause for concern is the battery level, 24%, combined with the drone's height, 538ft, and distance, 738ft.
If the column in the csv that is entitled "BATTERY.landTime" is the time in seconds until the critical battery landing triggers then at disconnection the drone was 54seconds from entering the critical landing process.

Reading the manual the drone the drone would, on disconnection, halt and hover for 11seconds leaving, just 43 seconds until critical battery forced landing (CBFL). Then it would retrace the last 50m of flight, which would also take time and reduce the time remaining until CBFL, so the time remaining until CBFL would be 43sec -x. Depending on what is considered to be "the last 50m of flight" the retrace may have resulted in the drone moving farther away from the home point which would also reduce the time remaining until CBFL to 43sec -x -y.

I do not know the RTH speed of the Air 2 and flying towards home should, I think, increase the time until CBFL but I think there is a chance that the drone entered CBFL whilst flying home, with no connection it would then have descended vertically and probably ended up in the sea.
You need someone better than me to check/verify that.

Why did you send the drone up to a height of 500m? The normal legal limit in Brazil is, I think, 122m, do you have the qualification/paperwork that might allow you to go higher than 122m?

Sean-bumble-bee Posted at 4-21 06:11
I am not certain that I am interpreting the csv correctly but what gives me cause for concern is the battery level, 24%, combined with the drone's height, 538ft, and distance, 738ft.
If the column in the csv that is entitled "BATTERY.landTime" is the time in seconds until the critical battery landing triggers then at disconnection the drone was 54seconds from entering the critical landing process. Reading the manual the drone the drone would, on disconnection, halt and hover for 11seconds leaving, just 43 seconds until critical battery forced landing (CBFL). Then it would retrace the last 50m of flight, which would also take time and reduce the time remaining until CBFL, so the time remaining until CBFL would be 43sec -x. Depending on what is considered to be "the last 50m of flight" the retrace may have resulted in the drone moving farther away from the home point which would also reduce the time remaining until CBFL to 43sec -x -y. I do not know the RTH speed of the Air 2 and flying towards home should, I think, increase the time until CBFL but I think there is a chance that the drone entered CBFL whilst flying home, with no connection it would then have descended vertically and probably ended up in the sea.
You need someone better than me to check/verify that.

I was descending the drone. I'm wondering why the data on this flight don't include what did the Air2 do after losing connection with the RC? Why is this information not written?

Most likely it lagged and didn't move, since we found Air 2 at night in the ocean by GPS location exactly where he lost contact with the RC and we found it without a battery.

Most likely, from a strong blow into the water, the battery fell out and was swept away by the tide. It was difficult to search for it waist-deep in water at night, and we gave up. Fortunately, we found the drone with a memory card.

Does DJI have any programs to investigate such incidents? In this situation, I do not see where my mistake is. This was my 199th flight. Okay, yes, I flew up the drone a little higher to take a nice photo of the landscape.

It doesn't affect his abitility to return to the HM 225m far away at the beach without any antennas or interference.

Ah I missed that you found the drone where the disconnection occurred. Given that the battery was not in the drone could it be that the battery disconnected from the drone, switching the drone off , and that the battery was ejected as the drone fell. That would seem to explain quite a bit.

Sean-bumble-bee Posted at 4-21 06:11
I am not certain that I am interpreting the csv correctly but what gives me cause for concern is the battery level, 24%, combined with the drone's height, 538ft, and distance, 738ft.
If the column in the csv that is entitled "BATTERY.landTime" is the time in seconds until the critical battery landing triggers then at disconnection the drone was 54seconds from entering the critical landing process. Reading the manual the drone the drone would, on disconnection, halt and hover for 11seconds leaving, just 43 seconds until critical battery forced landing (CBFL). Then it would retrace the last 50m of flight, which would also take time and reduce the time remaining until CBFL, so the time remaining until CBFL would be 43sec -x. Depending on what is considered to be "the last 50m of flight" the retrace may have resulted in the drone moving farther away from the home point which would also reduce the time remaining until CBFL to 43sec -x -y. I do not know the RTH speed of the Air 2 and flying towards home should, I think, increase the time until CBFL but I think there is a chance that the drone entered CBFL whilst flying home, with no connection it would then have descended vertically and probably ended up in the sea.
You need someone better than me to check/verify that.

Hi Sean,

The column BATTERY.landTime has a different meaning that you describe.
The value represent the time needed from current fly height to land craft safely in an autoland.
see my chart of this data.

Flying high (blue line = high number in secs, flying low = low number in seconds)

cheers
JJB

Thanks JJB I will have a look when I get on a windows computer.

Air2 Pilot in Brazil Posted at 4-21 15:44
I was descending the drone. I'm wondering why the data on this flight don't include what did the Air2 do after losing connection with the RC? Why is this information not written?

Most likely it lagged and didn't move, since we found Air 2 at night in the ocean by GPS location exactly where he lost contact with the RC and we found it without a battery.

Hi,

The moment there is a connection loss between drone and the RC, no flightog data can be  written in the log on the RC....

With no errrors in the log, flying at 164 meters height, distance out 225 meter and battery level at 24%, a normal RTH after connection loss can be expected.

As you find your drone at the connection loss position, most likely a total loss of power, perhaps due to battery dislodging...

cheers
JJB

JJB* Posted at 4-22 01:58
Hi,

The moment there is a connection loss between drone and the RC, no flightog data can be  written in the log on the RC....

How could the better dislogging in the air in a perfect condition? Is it a normal situation?

I assume that falling down from the altitude over 100m could lead to the loss of the battery according  to the strong impact on the water.  plus in the air the Drone could roll over during the fall, since there is always wind at sea.

Is it possible to receive any compensation or assistance from DJI?  Or does DJI give only a limited warranty and after 1 year any breakdowns even without the fault of the pilot are not their responsibility?

Air2 Pilot in Brazil Posted at 4-22 03:56
How could the better dislogging in the air in a perfect condition? Is it a normal situation?

I assume that falling down from the altitude over 100m could lead to the loss of the battery according  to the strong impact on the water.  plus in the air the Drone could roll over during the fall, since there is always wind at sea.

Hi,

Good question, mayby a other power failure in normal flight.
But beacuse drone was found at the last recorded position at disconnect, must have fallen out of the sky there.

Have no idea how DJI will react on anylyzxing your log, just start a case with DJI support.

cheers
JJB

Could the battery have been not fully clipped in or could it have swollen and popped out? The drone does seem to have been pitching and rolling quite vigourously and a not properly secured battery could have worked loose, I believe it is thought to have happened in other drones.