[size=14.6667px]today i was in the middle of a pretty normal flight and my s900+e1200+n3+lb2 decided to RTH. clear line of sight, not near any source of interference, full bars in DJI GO on both the hd and radio icons.

[size=14.6667px]i got a "tips: signal lost. aircraft returning to home point" and then it hightailed it to the home point at full speed. i could see the telemetry the whole time. i tried many times to cancel the RTH by tapping on the red x at the left and then confirming, but nothing. ditto once it decided to auto-land, tap to cancel, confirm, nothing.

[size=14.6667px]unfortunately my takeoff spot was pretty close to some trees (no other accessible open and level area near where i needed the shot) and so she clipped a branch on the way down and crashed from maybe 20 feet. probably lost one motor and arm, landing struts, a few props, some frame bits. the 22000mah lipo has a small dent.

[size=14.6667px]obvious question - how could it have "lost signal" if all the telemetry was still updating? total distance (taking into account the vertical) was a bit over 300 meters, clear line of sight. about halfway through the RTH, it also popped up a "warning: command timeout."[size=14.6667px]

[size=14.6667px]can DJI offer any assistance here?

We are so sorry for the mishap, if the drone is still in warranty period, please contact our support team to start a ticket and send in for data analysis, we will do our best to locate the problem, here is the link to obtain the support team: https://www.dji.com/support?site=brandsite&from=nav

here's an excerpt from the dat file. no explanation for how it went to "disconnected" despite 100 signal strength!

well, i got the results of DJI's log analysis back. "pilot fault," which i agree with since i should not have taken off in an area that had tree branches. of course, that wasn't the question - the question was why did it RTH with signal strength 100 and full telemetry/video still transmitted between aircraft and ground station.

here's a comparison of the air side and ground side logs.



it is interesting that signal strength varies through the flight until the point of RTH, where it's just pegged at 100. fundamentally though, i don't understand how it could be "disconnected" if the go app is receiving all the telemetry from the flight controller, e.g. the previse correspondence of the altitude tracking (blue line) in both the ground side and aircraft side even AFTER the disconnect.

sfmthd Posted at 2018-5-3 16:27
well, i got the results of DJI's log analysis back. "pilot fault," which i agree with since i should not have taken off in an area that had tree branches. of course, that wasn't the question - the question was why did it RTH with signal strength 100 and full telemetry/video still transmitted between aircraft and ground station.

here's a comparison of the air side and ground side logs.

What do you use to analyse the data logs? need to do some with my system. Thanks

i found csvview to be the easiest.

https://datfile.net/

sfmthd Posted at 2018-5-13 17:12
i found csvview to be the easiest.

https://datfile.net/

thanks for the information