I have a DJI Phantom 3 4K. I have had it for a couple of years and flown it off and on but not in the last year or so. I decided I wanted to get it out of the closet and begin flying again. I did, linked it with the new DJI Go app, updated all of the firmware etc... and flew a couple of missions. It seemed to lose signal pretty quickly though. Based on that, I downloaded and bought the Litchi app to try that. I verified that the DJI GO app was completely disabled and off, and used Litchi. I flew a short mission and had issues where I had to put it back in P mode and hit the RTH button, but figured it might just have been a glitch so I made a new mission that was shorter and tried it again. Both of these missions were less than 400 feet from me and the controller, but with Litchi I was under the belief it would not matter. Well, the second mission went worse than the first. It seemed to hit the first couple of way points without issue, but when it began coming back after the 5th waypoint, it just stopped and I could not see it moving on my screen. I am using an LG V30 phone, so from a hardware specification perspective it is a fairly good device. I could hear my drone, but not see it, and it was obviously not moving anymore. I put it back in the P mode and hit RTH and nothing happened, it just kept saying loss of signal. Then I began walking back towards it to get a better signal, and I heard it crashing through the trees. I found it on the ground upside down and relatively intact other than some scrapes on the propellers. Attached are the screen shots of the mission (As Planned), and what apparently happened shown on the mission hub (As Flown). Also Attached is the log file. Any help would be appreciated. I have seen on the DJI forum a lot of people complaining about the latest Phantom 3 firmware updates and I'm wondering if that has something to do with it. I have attached the planned mission with the waypoints, and the as flown mission, and also attached the flight logs. I am at a loss as to what happened.


Thanks

Sorry for your troubles.  

You say you put it "back in P mode."  What mode was it in before?  

I had it in F mode.

Are you sure your altitude at each waypoint took into account any changing elevation and tall trees?  

Did you watch the video and did it gain you any insight?  

Yes, I took trees into consideration on the altitude, and the video failed to record.

P3-4K-FL Posted at 2018-3-3 17:46
Yes, I took trees into consideration on the altitude, and the video failed to record.

I have a P3A, and have used Litchi literally for over 60 waypoint missions, without any problems at all. I'm sorry for your problems. If in "F" mode, and waypoint mission uploaded correctly, it should perform flawlessly regardless of your mobile device, no matter if it lost signal or not. I have flow numerous missions where I know I will lose signal, but it has always completed the mission. Are you sure your altitudes were correct? Was your last waypoint back close to your home point? Did you have your "action" after the mission to RTH, hover, or do nothing? Several things to consider. Like I said, I have never had any issue with Litchi, but you must also have the settings correct for what you want to do. Maybe give us more info and hopefully we can help figure what happened.

I too have had multiple successful mission flights with Litchi.  Once, one did come back early though.  I don't remember many details - it was almost three years ago and I was such a noob.  I even forgot to start the video.  It might have come back due to low battery RTH.  

Are you sure you launched with a fully charged battery?  

Is your failsafe set to RTH and not hover?  

Mark The Droner Posted at 2018-3-4 04:19
I too have had multiple successful mission flights with Litchi.  Once, one did come back early though.  I don't remember many details - it was almost three years ago and I was such a noob.  I even forgot to start the video.  It might have come back due to low battery RTH.  

Are you sure you launched with a fully charged battery?  

Like Mark said, some time back (can't remember which version), but Litchi would RTH if "Smart-Return Home" was toggled on in your DJI GO app. Litchi can't override this because it is embedded in the firmware. Smart return home kicks in when if the phantom senses too low of a battery voltage and don't think it can return home. This is the only thing Litchi will do when running a mission. Took me a while to figure out too. I was running the same missions I ran before and found my phantom RTH about 2/3 of the way thru the mission. It should go to the altitude set for RTH though. The way to avoid this it to turn "OFF" the smart-return home in the DJI go app. Don't worry no problems. Just keep an eye on your voltage! This only happens when you have a long distant run. You flight looks pretty short distance. You can toggle in Litchi to have it start recording upon takeoff too. Waiting for you to respond to some of our questions.................

Another comment. The minute you switched to "P" mode, that takes you out of the waypoint mission! Even if you put it back to "F", it will not just restart the mission. You said it said lost signal, once you got out of the mission, and it possible went into regular mode, the lost signal might have triggered RTH. double check those altitude settings.

Thanks, I don't know if I have the RTH on in the DJI app, but I'm assuming I do. I do know my battery was at 89% when I started the mission, and it was only a 5 minute mission. I will check that and see where I end up. Thank you all for the comments, I appreciate it.

It's very important to always launch with a full charged battery.  

Is 89% too low?

Do you have birds in your area? I suspected a flock of Crows knocking my Phantom out of the sky last fall, and into the trees. Similar situation, it just stopped moving on my screen, and I watched the Crows fly up from the same area.

No, we have a nesting pair of Hawks who seem to keep everyone clear on the bird front. That would be weird though, a drone bird strike

I am very sorry for the crash. For the drone, please kindly send it back for repair, but please kindly note that we don't provide the warranty and data analysis service if the drone expired the warranty period. Thank you for understanding. If there is a need, please contact our support for a further help: http://www.dji.com/support

DJI Thor,

Thanks for the reply, the drone survived without damage. I am just trying to determine why. I'll go through the logs and see if there is anything, but I did start with a fairly full battery 89% and a short mission. I have not had the chance to check the RTH setting in the DJI app, but I'll do that tonight.

One question for the crowd, do I have to have both apps installed on the device? I was using a brand new phone with only the Litchi app installed. I have seen warnings everywhere that state you must ensure that you only have one app running at a time, so I assumed I did not need to have the DJI GO installed. I had previously (within the last week prior to the crash) updated on my old phone with the DJI GO app, but when I got the new one, I just didn't install it. Could that have had something to do with it?
Thanks again for the help.

P3-4K-FL Posted at 2018-3-5 05:33
DJI Thor,

Thanks for the reply, the drone survived without damage. I am just trying to determine why. I'll go through the logs and see if there is anything, but I did start with a fairly full battery 89% and a short mission. I have not had the chance to check the RTH setting in the DJI app, but I'll do that tonight.

You must actually go into your app settings, and pick the one app you are not going to use, and then click on "Force-Stop" to remove it from running in the background. A lot of people make the mistake of thinking that if the app is not opened up that it is not running. That is totally incorrect!  I have a normal routine of going into my app when I am going to fly and toggle both my Litchi and GO app "off". Then when I plug in my usb cable it always asked which app I want to use. I also always pic "This time only" instead of picking "use this a default". That way I will get asked each time. I constantly change from one to the other depending on what I am doing. Might sound strange, but each has it own advantages, and you have to have the GO app to set some settings such as "EXP, Gain, Sensitivity".....which I do play with on occasion but others may chose not to. Anyway to answer your question you have to "Force-stop" the app to keep it interfering with the other one. This wouldn't have caused your problem though in my opinion. It may have cause the Litchi app to act strangely or even crash, but like mentioned before, if the mission was loaded up to your phantom, it will run the mission completely whether it has signal or not. With that being said of course if your phantom was to fly lets say under a bridge or something where GPS was lost, it would cause the aircraft to lose position, but that would be a very unusual situation. But that doesn't look to be your issue. I still think maybe when you toggle the switch from "f" to "p' you could have exited the mission, that's when something went wrong.