Almost lost my new Standard today during a mission

[zsoltipal]

Hi guys. I've got my new P3S two weeks ago and it's been so much fun learning it's features and having a lot of fun without incidents... so far. I prepared a waypoint mission for Litchi in the Mission hub today, it was a 4km roundtrip. I used a windsurfer and the papatita mod to extend the range of my phantom. So, it was around -2 degrees Celsius outside, I started the mission and I had FPV signal for the whole time, I lost controller signal a few times for 1-2 seconds but the signal came back as I adjusted the controller towards the drone. When the drone reached the farthest waypoint Litchi said "mission has ended", but I could see on the phone that the drone was still doing it's mission. On it's way back I set it to fly a little lower in the mission hub, so I had weak signal, even lost it a few times due to some buildings, but I still had fpv. Then it happened, the drone switched to RTH mode and cancelled the mission for some reason. A few seconds later I regained controller signal and told it to cancel the RTH and at that moment my iphone died (it was 80% charged before I started, but I guess the cold drained the battery down). I used the RTH switch to bring the drone back and landed it safely, fortunately it was hovering close by so I had signal to do it.

Now my question is, what could have triggered the RTH during a waypoints mission in Litchi? I thought the loss of signal wouldn't affect a mission? The drone was fully charged before taking off. Could the failsafe in the DJI app have initiated the RTH when I lost signal for more than 3 seconds?

Here's my flight log which ended when my phone died:

HealthyDrones.com - Innovative flight data analysis that matters

 

[Spiderpig]

It might have gotten to critical battery level and initiated RTH mode. Not sure. But glad you got it back.

 

[zsoltipal]

Thank you. It had 50% battery when I landed it

 

[Kirby Johnson]

Litchi..........................?

 

[zsoltipal]

Yeah. You never heard of it?

 

[Spiderpig]

Litchi an awesome app. Makes the P3S more functional.


Sent from my iPhone using PhantomPilots

 

[GhostRdrTat]

Litchi an awesome app. Makes the P3S more functional.


Sent from my iPhone using PhantomPilots

Agreed, just be aware of it's glitches and keep up on forum threads to see any new ones people report so you can stay on top of it and be prepared.

 

[Kirby Johnson]

Yeah. You never heard of it?

Oh yeah, I have heard of it hundreds of times, guys telling stories like yours. But mostly starting with...Oh Lord, I lost my PXX today.

 

[neven]

Oh yeah, I have heard of it hundreds of times, guys telling stories like yours. But mostly starting with...Oh Lord, I lost my PXX today.

Can you link some of those threads/stories?

Sent from my SHIELD Tablet K1 using PhantomPilots mobile app

 

[Cookie$Dough]

I used to fly with my iPhone6 also, but it too would die after only a few minutes of being used. I switched to my iPad2 mini since, and have had no problems since. I only use the DJi go app.


Sent from my iPhone using PhantomPilots

 

[WilliamM]

Oh yeah, I have heard of it hundreds of times, guys telling stories like yours. But mostly starting with...Oh Lord, I lost my PXX today.

Litchi an awesome app, don't know what your talking about. People loss their drones using any app.

 

[WilliamM]

Thank you. It had 50% battery when I landed it

It's not just the battery % that's important, but the cell voltage that's even more important. So maybe being it was so cold outside your battery got cold before the flight. Did you try to keep it warm before the flight?

 

[With The Birds]

If you have smart RTH enabled in DJI GO turn it off. It is way to conservative. The setting will be enabled even when flying LCMC in litchi. The mission will abort and RTH initiate when the algorithm determines the AC should RTH based in battery status.

 

[Kirby Johnson]

Can you link some of those threads/stories?

Sent from my SHIELD Tablet K1 using PhantomPilots mobile app

Go into the General Forums here, then under Software, then Control and browse the posts.

 

[Spiderpig]

So the best advice I can give when using Litchi or even GO app in any automated modes is to have your finger up on the mode switch. If something doesn't look right move it from F to P. I used to move it to ATTI, but you never know about wind conditions at altitude, so easy to flip it up all the way and then recover the drone. Remember - always be in control!

 

[With The Birds]

Go into the General Forums here, then under Software, then Control and browse the posts.

Or even better, litchi AND crash.

Fact, almost without exception operator error is the issue. Poor waypoint planning, Failsafe settings (behaviour and RTH height), user panicking and switching out of mission with poor connection and/or lacking the experience to fly home manually etc. There are known issues with litchi where the current DJI firmware/SDK issues cause RTH not to initiate in certain flight modes on the standard. There is also a problem with how NFZ are reported and litchi behaviour.

The biggest problem with Litchi (and other third party apps) is where you have an issue and the AC isn't recoverable. DJI will not accept the litchi flight log data as evidence of the cause and will be reluctant to entertain warranty claims. where the AC flight log is available it seems DJI will happily warrant hardware and DJI software failure without issue.

 

[Spiderpig]

Or even better, litchi AND crash.

The biggest problem with Litchi (and other third party apps) is where you have an issue and the AC isn't recoverable. DJI will not accept the litchi flight log data as evidence of the cause and will be reluctant to entertain warranty claims. where the AC flight log is available it seems DJI will happily warrant hardware and DJI software failure without issue.

I agree with this quite a bit. Even in automated modes when the drone is safe, you still don't have control over it. I was testing out the tracking mode, and it lost the target and started looking for it. When it gave up it maintained a hover, but no stick movement would do anything. Thankfully I always have my finger around the mode switch when in automated flight and flipped it all the way up and re-covered control. So the biggest lesson is aways be ready to flip the switch and take control. Litchi has crashed my drone once, and came close plenty of times and thankfully I was able to flip the switch and get it out of harms way.

 

[QuadcopterCrazy]

I don't know if Litchi has actually ever lost a drone, a case could be made that it could happen any time with the amount of threads complaining about Litchi glitching out.

 

[zsoltipal]

It's not just the battery % that's important, but the cell voltage that's even more important. So maybe being it was so cold outside your battery got cold before the flight. Did you try to keep it warm before the flight?

Yes I kept it wrapped up in a hat and it was in my pocket for a few minutes till I set everything up. According to the flight log the battery was operating normally, it shows a voltage drop of 0.02v when it was descending and it shows it had 70% when my phone died. Weird, the only thing I can think of is the signal strength which was poor for a few seconds before RTH was iniciated in Litchi.

If you have smart RTH enabled in DJI GO turn it off. It is way to conservative. The setting will be enabled even when flying LCMC in litchi. The mission will abort and RTH initiate when the algorithm determines the AC should RTH based in battery status.

I will try that next time with the drone not too far away.

So the best advice I can give when using Litchi or even GO app in any automated modes is to have your finger up on the mode switch. If something doesn't look right move it from F to P. I used to move it to ATTI, but you never know about wind conditions at altitude, so easy to flip it up all the way and then recover the drone. Remember - always be in control!

I switched it to P-GPS mode when the phone died, that helped the drone hover while I was deciding what to do. It was hovering close be, I could hear it so I used the S1 switch to initiate RTH and it came home.

Thanks for all the replies guys, next time (I hope there won't be a next time) I will be ready. My RTH altitude is set to 100 so it shouldn't crash into anything and also, I will launch it from a hill so I can have full signal all the time.

 

[With The Birds]

You are unlikely to observe smart RTH initiating during a mission if you are flying in close, the AC calculates power required to RTH based on distance from launch point (home) in a straight line.

Also if flying from a hill RTH height can be set lower. I wouldn't recommend 100m as you have proposed as if the AC does initiate RTH it will almost certainly climb way above 400ft AGL and will use battery power unnecessarily during the ascent phase.