So we lost a Mavic today and I would like to figure out exactly why. Totally our fault. We were caught unprepared by the autoland and didn't cancel it before the drone dropped below the trees. But the reason why it went into auto land is what I want to know. This is a complicated one so bear with me.
A friend and I were out doing distance runs with virtually identical Mavics. The first run we used a recent DJI Go 4 and were also using the DJI goggles. The flight is about 2 miles up the side of a mountain with a significant height climb. On my trip out I get a warning at around 55% battery that says, effectively, "you only have enough battery to return home, starting RTH unless canceled". So using the Goggles I cancel the warning. I know I am going "uphill" and will have plenty of battery to get back. I finish the flight with 40% battery, no problem.
Now my friends turn. Everything identical except he is using Litchi. We are still using the Goggles (one person observing). Now on the way out we get the warning again about RTH unless canceled. We cancel in the goggles again. Everything seems fine but 10 seconds later at exactly 50% battery there is a warning in the goggles that says something about battery and starts auto landing. Due to where it was we only had a few seconds to react and were unable to stop it from dropping beyond line of sight and it presumably landed right where it was. Not recoverable until at least the snow melts.
We have the Litchi .csv logs in the phone and the DJI .txt logs from the goggles (thank god for that btw). I can't share them yet because they would pinpoint the location of my friends drone and he wants to try to get it.
Battery problems seem obvious but it was a good freshly charged battery and looking at the logs shows NO battery problems. When we lost contact it said 48% battery and all cells had steady 3.7 voltage on all cells and no spikes.
As far as the messages go Litchi doesn't seem to record them, at least in the csv. The goggles logs also don't seem to show verbatim messages. The message in this log from AirData is "50% Battery at maximum distance" just before it started its autoland.
So what happened? What combination of factors resulted in it deciding to land where it was. I think in part it was the low battery behavior that should have caused it to go into RTH somehow made it decide that because it didn't have enough battery to get home its best course was to land now. Or was it because the RTH was canceled in the goggles but not in litchi? We are not totally sure we saw even saw the RTH warning on the litchi screen. It may have only been in the goggles.
As I said. Complicated. Anyone hear of anything like this?
A friend and I were out doing distance runs with virtually identical Mavics. The first run we used a recent DJI Go 4 and were also using the DJI goggles. The flight is about 2 miles up the side of a mountain with a significant height climb. On my trip out I get a warning at around 55% battery that says, effectively, "you only have enough battery to return home, starting RTH unless canceled". So using the Goggles I cancel the warning. I know I am going "uphill" and will have plenty of battery to get back. I finish the flight with 40% battery, no problem.
Now my friends turn. Everything identical except he is using Litchi. We are still using the Goggles (one person observing). Now on the way out we get the warning again about RTH unless canceled. We cancel in the goggles again. Everything seems fine but 10 seconds later at exactly 50% battery there is a warning in the goggles that says something about battery and starts auto landing. Due to where it was we only had a few seconds to react and were unable to stop it from dropping beyond line of sight and it presumably landed right where it was. Not recoverable until at least the snow melts.
We have the Litchi .csv logs in the phone and the DJI .txt logs from the goggles (thank god for that btw). I can't share them yet because they would pinpoint the location of my friends drone and he wants to try to get it.
Battery problems seem obvious but it was a good freshly charged battery and looking at the logs shows NO battery problems. When we lost contact it said 48% battery and all cells had steady 3.7 voltage on all cells and no spikes.
As far as the messages go Litchi doesn't seem to record them, at least in the csv. The goggles logs also don't seem to show verbatim messages. The message in this log from AirData is "50% Battery at maximum distance" just before it started its autoland.
Code:
Flight time Altitude Home Distance Type Notification
A 00m 00s 0.0 ft 0 ft Mode Mode changed to Motors_Started
B 00m 00s 0.0 ft 1 ft Tip Setting new Return-To-Home altitude to 30m (98 ft).
00m 00s 0.0 ft 1 ft
100% Battery
C 00m 01s 0.0 ft 1 ft Mode Mode changed to Assisted_Takeoff
D 00m 01s 0.0 ft 1 ft Mode Mode changed to GPS_Atti
01m 36s x167.6 ft 1,526 ft
90% Battery
E 01m 56s 610.9 ft ,155 ft Data Loss Downlink data connection lost for 1 seconds
F 02m 00s 673.5 ft ,248 ft Data Loss Downlink data connection lost for 1.1 seconds
G 02m 00s 673.5 ft ,248 ft Mode Mode changed to WiFi_Reconnect
H 02m 01s 676.2 ft ,269 ft Mode Mode changed to GPS_Atti
02m 42s 536.4 ft ,464 ft
80% Battery
04m 35s 463.2 ft ,721 ft
70% Battery
06m 55s 947.8 ft ,266 ft
60% Battery
08m 52s 138.1 ft ,293 ft
50% Battery
08m 54s 138.1 ft ,296 ft
50% Battery at maximum distance
I 09m 04s 138.7 ft ,276 ft Mode Mode changed to AutoLanding
J 09m 16s 063.3 ft ,272 ft Mode Mode changed to WiFi_Reconnect
K 09m 17s 049.5 ft ,273 ft Mode Mode changed to AutoLanding
L 09m 18s 033.1 ft ,273 ft Mode Mode changed to WiFi_Reconnect
So what happened? What combination of factors resulted in it deciding to land where it was. I think in part it was the low battery behavior that should have caused it to go into RTH somehow made it decide that because it didn't have enough battery to get home its best course was to land now. Or was it because the RTH was canceled in the goggles but not in litchi? We are not totally sure we saw even saw the RTH warning on the litchi screen. It may have only been in the goggles.
As I said. Complicated. Anyone hear of anything like this?
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