RTH isn’t triggered on disconnection when in F mode with the Autopilot app (SDK)

[nonflyingbrick]

Yesterday I was flying with the iOS Autopilot app at around 1000 meters distance and I lost connection. It took me over a minute to regain connection. The surprising thing is that RTH wasn’t triggered. I checked the RTH setting on the DJI Go app after and it was set to return to home, not hover. The firmware on the drone and RC is 1.4.30, the Autopilot app is the latest, 2.2, and the DJI Go is the latest, 2.4.2.

This morning I went out to test again and I can conclusively say: When flying F mode with the Autopilot app, RTH is not triggered even after a minute of disconnection, but when I switched back to P mode and opened the DJI Go app, RTH is triggered (after just 3 seconds, of course).

I'm worried, I often do very remote missions with Autopilot, places where it's possible to lose connection and not be able to regain it without the aircraft getting back closer by itself.

 

[Meta4]

Yesterday I was flying with the iOS Autopilot app at around 1000 meters distance and I lost connection. It took me over a minute to regain connection. The surprising thing is that RTH wasn’t triggered.
I'm worried, I often do very remote missions with Autopilot, places where it's possible to lose connection and not be able to regain it without the aircraft getting back closer by itself.

That's something to be aware of and plan the mission with that in mind.
Because F mode can be used for flights that go behind an obstacle and lose signal, it doesn't RTH on loss of signal.

 

[nonflyingbrick]

But I've read on the forum that F mode does RTH on the DJI app. In fact, when I set up a POI mission on the DJI app (and you have to be in F mode to do that) the app asks me to confirm the RTH height saying that it will RTH on signal loss. So it's something about SDK apps or maybe just the Autopilot app in particular, it's not F mode in general.

 

[Oso]

You set the RTH height in F mode in case you initiate a RTH manually. An auto RTH will not initiate with lost signal (as normal when not in F mode) since it would defeat the benefit of being able to set up and execute a mission. The expected behavior while executing certain missions is that if signal is lost the P3 will continue with the mission until low power and then may land. Maybe even if over water.

Here's a thread about it from 3 months back when the autonomous features were first included in new FW:
Auto RTH lost with new features? | DJI Phantom Forum

 

[nonflyingbrick]

Hmm that doesn't sound safe, however I don't think that's the actual behaviour... Today when I run a POI mission in the DJI app I read more carefully the message and what it actually says is "The aircraft will return to the Home Point if Low Battery RTH is triggered." So it seems that RTH won't be triggered on signal loss in F mode, but apparently Low Battery RTH will. I've also been flying in F mode with Autopilot today and I had Low Battery RTH triggered as Autopilot was flying (and while signal was OK).

Thanks for commenting.

 

[Oso]

Hmm that doesn't sound safe, however I don't think that's the actual behaviour... Today when I run a POI mission in the DJI app I read more carefully the message and what it actually says is "The aircraft will return to the Home Point if Low Battery RTH is triggered." So it seems that RTH won't be triggered on signal loss in F mode, but apparently Low Battery RTH will. I've also been flying in F mode with Autopilot today and I had Low Battery RTH triggered as Autopilot was flying (and while signal was OK).

Thanks for commenting.

It's safe if you understand the behavior of each feature and plan accordingly, just as @Meta4 noted earlier in the thread. Whether you do that or not is your decision of course. Cheers!

 

[nonflyingbrick]

I haven't flown waypoint missions so I can't comment on that, but Autopilot doesn't fly the drone when it's not connected (it's not possible to program something that will go on executing after signal is lost with that app), so having the drone land on a random point where it lost signal wouldn't be safe, that's why I made that comment.

 

[aka1ceman]

I thought that it would upload the way point information to the drone when the mission begins, so that way he could continue the mission without needing signal. Correct me if I'm wrong.

 

[nonflyingbrick]

No, the Autopilot app flies the drone on real time. It yaws the drone and tilts the gimbal on realtime to focus on a specific subject when that's what you set it up to do, something most likely not possible to program into the drone.