Lost total control of the AC. What happened here?

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TLDR; Running Go4. Lost connection momentarily and RTH initiates. Thereafter the AC would not take ANY commands - from app (command timeouts) or RC. Returned to home but stopped landing at about 9+ ft due to “unsafe landing area.” Had to wait for batt to get to basically zero before it came down low enough to catch. Whew.

.....

The whole story plus logs...

Flew my P4P out from a lake shore out over the (frozen) lake and turned to come back when battery was about 60% (a minute or two before that I got a warning that it was returning to home due to low batt. I was heading out on a headwind. So coming back would be a tailwind and I knew I’d have plenty of batt to get back. I was right).

On the way back it lost connection momentarily. Not sure if I ever lost downlink. Connection came back but it was R’ingTH. I wanted to take control back so I hit the X in Go4 to cancel RTH so I could continue to fly back manually. I got a “Command Timeout.” I kept trying multiple times with command timeout every time. Video and telemetry were fine. I tried to use the sticks to speed up or drop altitude - no response. I tried to cancel RTH with the button on the controller. It stopped beeping for about 5 seconds, then started beeping again. RTH continued. So I let it come back. (I hacked the RTH speed to be faster than stock so I was feeling that would help.)

My concern was what would happen when it came back and did autoland. I wasn’t in an open field. I was on the edge of a lake with benches and a road. And some grass. Could I take control and land it myself?

No.

It got overhead at about 350 ft or whatever alt it was flying at last I had control and started autoland. It was coming down in an OK spot. Not over the bench I launched from but a few feet away over some grass. I still wanted to catch it if I could because some rock sticking out of the ground a foot away. But I had no control.

It got to about 9 ft (eyeball estimate) off the ground and stopped - warning that it was an unsafe area to land. And it wouldn’t land. And I couldn’t force it to. I figured I’d wait for critical battery to force a land and I’d catch it because the ground below wasn’t perfect. edit: obstacle avoidance was off. There may be a setting to disable the safe landing. I’ll have to check and memorize that.

I waited for it to hover from about 25% battery all the way down below 10%. Then 5%. I got warnings saying it was landing due to critical battery.

It wasn’t landing.

It continued to hover. I killed the app and restarted. I restarted the RC. It reconnected fine as far as downlink. But still no control.

Continued to hover. So I figured it would hover till the battery died and shut the motors off. Didn’t think it would completely survive a 9+ ft fall so I waited to catch it in free fall.

Much to my relief it start a slow descent at 1% batt or less. So I gently caught it by the landing gear and it shut off.

The drone had a mind of its own. I’m just glad it was a sane mind. But now I need to figure out what happened.

Any ideas would be appreciated. I’m charging the battery now to see if the problem persists.

Here is the airdata link of the main flight (there is a separate one for the landing but I doubt it’s interesting):

Airdata UAV - Flight Data Analysis for Drones

Here is the phantomhelp upload of the main flight from Go4:

DJI Flight Log Viewer - PhantomHelp.com

I’ll post more info from the power up when that happens.
 
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Powered it up in the house with no props and all seemed normal. Responded to stick input to start the motors and revved when I pushed the left stick forward. This isn’t good news because I don’t like non-reproducible problems like this.
 
obstacle avoidance was off. There may be a setting to disable the safe landing. I’ll have to check and memorize that.
There is, it for the VPS not for OA. Haven't had the chance to look through the data as of yet, but surely someone will.....
 
There is, it for the VPS not for OA. Haven't had the chance to look through the data as of yet, but surely someone will.....
Yes I found that setting already. Thx.
 
Powered it up in the house with no props and all seemed normal. Responded to stick input to start the motors and revved when I pushed the left stick forward. This isn’t good news because I don’t like non-reproducible problems like this.
The data confirms what you said but doesn't shed any light on the mystery of why it did that.
 
It was the compass. Its always the compass, lol.

Taking off from a bench?
From on top of my case on top of a flat concrete bench. Someone will ask if it had rebar in it LOL. This isn’t a compass issue obviously. Not only did I receive no errors, the aircraft flew perfectly out 3 Miles. And, in fact flew itself back perfectly right to within a couple feet of the landing spot. Then held station perfectly in a breeze while the battery died down. It just either simply wouldn’t respond to ANY commands or the RC wasn’t sending them. I even tried switching it to ATTI and sport mode while it hovered. No response. And, in fact, the log doesn’t even show a switch to those modes.
 
I keep all OA and VPS off. I'd use if I needed it but I never do and I simply don't trust VPS. Doesn't really matter though as these things will throw a glitch at you whenever they feel like it. The only thing I might have thought to try was switching to the opposite of what you were set on for 2.4/5.8. But regardless, you'll probably never know what really happened because it's likely a one off. I had my remote beep at me before flight the other day that the sticks needed calibration. I didn't have the luxury of doing that at the moment. I rebooted the rc and it cleared. Hasn't happened since. Strange, and in your case potentially really serious, stuff happens and never happens again. The best you can do is fly conservatively for a bit and make sure all seems well. Do a couple rth in ideal conditions in case there's a problem. Hopefully this will become a distant albeit nagging memory. Probably a one off software glitch that is unlikely to happen again.
 
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I keep all OA and VPS off. I'd use if I needed it but I never do and I simply don't trust VPS. Doesn't really matter though as these things will throw a glitch at you whenever they feel like it. The only thing I might have thought to try was switching to the opposite of what you were set on for 2.4/5.8. But regardless, you'll probably never know what really happened because it's likely a one off. I had my remote beep at me before flight the other day that the sticks needed calibration. I didn't have the luxury of doing that at the moment. I rebooted the rc and it cleared. Hasn't happened since. Strange, and in your case potentially really serious, stuff happens and never happens again. The best you can do is fly conservatively for a bit and make sure all seems well. Do a couple rth in ideal conditions in case there's a problem. Hopefully this will become a distant albeit nagging memory. Probably a one off software glitch that is unlikely to happen again.
Yeah I hope you’re right. I did think, after the fact, about switching the frequency but GO4 says that setting if for image transmission signal so I figure it wouldn’t affect the RC control uplink.
 
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Hi Bill,

Something very similar (or identical) happened to me this afternoon. Was about to land my Phantom 4 Pro after low battery warning. Had plenty of juice (screen showed 20-30%) but drone went into RTH. I prefer to land manually and grab it so I canceled on the screen and then the drone was stuck hovering about 10-15 ft up in the air.

Nothing would change that - I closed the DJI 4 app on my iPad, etc. flicked the switch from A to P to S (which worked to reset my P3P once in the past) Nothing. No stick movement would budge it. I watched the battery slowly drain and eventually the drone landed on a low roof that I was able to reach with a ladder... No evident damage and battery charged and seems to be ok. Didn't fly it since and looking for some answers as I am not liking this.

What is the setting you found to disable safe landing? Is there any way to regain control of the drone after it reaches the dreadful “Command Timeout"?

This is my first post here. Thank you,

Alon
 
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Welcome to the forum Alon :)

Thank you! Good to be here - I've browsed the site several times in the past but didn't want to post since I never had an important question or something to add to the discussion - obviously that changed with today's incident. I look forward to participating and learning more.

Alon
 
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Hi Bill,

Something very similar (or identical) happened to me this afternoon. Was about to land my Phantom 4 Pro after low battery warning. Had plenty of juice (screen showed 20-30%) but drone went into RTH. I prefer to land manually and grab it so I canceled on the screen and then the drone was stuck hovering about 10-15 ft up in the air.

Nothing would change that - I closed the DJI 4 app on my iPad, etc. flicked the switch from A to P to S (which worked to reset my P3P once in the past) Nothing. No stick movement would budge it. I watched the battery slowly drain and eventually the drone landed on a low roof that I was able to reach with a ladder... No evident damage and battery charged and seems to be ok. Didn't fly it since and looking for some answers as I am not liking this.

What is the setting you found to disable safe landing? Is there any way to regain control of the drone after it reaches the dreadful “Command Timeout"?

This is my first post here. Thank you,

Alon
Uh oh. So you got command timeout too? Disconcerting. I guess a report to DJI may be in order. I fear they will just tell me to upgrade. And I’m holding at the last “golden” release.

I can’t find the setting in GO4 at the moment. I may need to fire up and connect to the AC in order to see it. I’ll do it tomorrow and post.

So far I know of no way to regain control. I flew today and it was fine so I didn’t reproduce it. But it seems as if the aircraft went deaf or the controller went mute. If you know what I mean. It was quite a pickle standing there with it out of reach.

But your situation was worse since it was over a roof. If your bird was telling you it wouldn’t land because of unsafe below then I don’t know that disabling that safety would help. Because it could have given you time to scramble up there and catch it.
 
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Uh oh. So you got command timeout too? Disconcerting. I guess a report to DJI may be in order. I fear they will just tell me to upgrade. And I’m holding at the last “golden” release.

I can’t find the setting in GO4 at the moment. I may need to fire up and connect to the AC in order to see it. I’ll do it tomorrow and post.

So far I know of no way to regain control. I flew today and it was fine so I didn’t reproduce it. But it seems as if the aircraft went deaf or the controller went mute. If you know what I mean. It was quite a pickle standing there with it out of reach.

But your situation was worse since it was over a roof. If your bird was telling you it wouldn’t land because of unsafe below then I don’t know that disabling that safety would help. Because it could have given you time to scramble up there and catch it.

Yes - similar situation. Message on the controller was Command Timeout. I canceled RTH and then it got stuck... I had over 10 minutes of battery left and nothing worked to move it. I was very lucky that it slowly self landed in spot on a roof that low and reachable but I am worried about future flights now... Will try to look at the log more carefully today and see if I can contact DJI with this. I think I am on the latest DJI app and drone firmware.
 
Had a chat session with DJI support. They say it could have been interference on my transmission signal. I was fairly close to village power lines at that point so that could be the case. I flew in the area without problems in the past but this time I was closer to power lines than before. They recommended doing the IMU, compass and remote calibration before next flight. We shall see!
 
Had a chat session with DJI support. They say it could have been interference on my transmission signal. I was fairly close to village power lines at that point so that could be the case. I flew in the area without problems in the past but this time I was closer to power lines than before. They recommended doing the IMU, compass and remote calibration before next flight. We shall see!

Unfortunately, I'm afraid your instructions from DJI support staff have been what may be considered a default response to questions they have no factual resolve.
If not too much of a bother, could you provide the present f/w versions on both controller and model, as well as the DJI GO version used, out of curiosity.
Maybe, there is some correlation there between you and the OP, particularly if using a recent f/w update, and see how now there are more than one pilot this issue has shown its ugly face to. : )
 
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Yeah I hope you’re right. I did think, after the fact, about switching the frequency but GO4 says that setting if for image transmission signal so I figure it wouldn’t affect the RC control uplink.

Can you provide which f/w versions you had been using on the model and controller, as well as version of the GO app. when this incident had occurred. A very unsettling concern I must admit, particularly in light of the very same issue occurring to more than one pilot since your initial post, and both within a couple hundred miles of each other in NY. Probably just a coincidence.

Regards,
 
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Unfortunately, I'm afraid your instructions from DJI support staff have been what may be considered a default response to questions they have no factual resolve.
If not too much of a bother, could you provide the present f/w versions on both controller and model, as well as the DJI GO version used, out of curiosity.
Maybe, there is some correlation there between you and the OP, particularly if using a recent f/w update, and see how now there are more than one pilot this issue has shown its ugly face to. : )
I wholeheartedly agree with your assessment of this being a default response. I suspect they didn’t tell him to update the firmware only because he’s running the latest.

In my case, no way in H E double hockey sticks it was interference. I flew 3 miles out and was on the way back at pretty close to the max distance when the problem started - and continued all the way back and was persistent as I stared up at it 10+ ft above my head.

I’ll let you know my firmware when I get a chance to fire up the bird. But this may tell you all you need to know:

The RC must be the latest. I don’t think I get any warnings to update that.

I deliberately downgraded the AC to the version that “everyone likes.” I think it’s the .509 version. It’s the last one you can modify parameters such as RTH speed and such.

Edit: I researched. It must be V01.03.0509.

GO4 is the latest. But unrelated. Because this is a problem between the RC anc AC. So it could be RC firmware. I don’t know the version but I’ve not upgraded it recently (or at all. I bought it a couple months ago). And I don’t think it’s asking me to upgrade.

Besides, they didn’t tell you “oh that’s a bug in the x.y.z version of the RC firmware.” It tells me what I suspect. They haven’t heard of this or don’t know the answer.

Another edit: I just flew it again. No distance. Just a close in flight. No problems.
 
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Might be worth reflashing the firmware on the AC just in case one of the modules became corrupted. That might explain the command timeout problem as it is waiting for a response that is expected but doesn't happen due to corrupted code.
 
[QUOTE="bsartist, post: 1350357,

Another edit: I just flew it again. No distance. Just a close in flight. No problems.[/QUOTE]

That's comforting to hear, and hopefully the issue doesn't ever reoccur.
A Command Timeout code as described by Timinator is something from my understanding anyway that can occur for various reasons and between various models of the DJI series. Some have received this code with the same affect as you've described after updating the software version of their device. eg. ( when updating to IOS version 11.1) whether this was actually what had caused the issue or not, not sure, but something which had been occurring to many who for one reason or another had updated the software, thus creating havoc between the GO app and the device used until a later version became available. However, while software/firmware upgrades are necessary, to some degree are at times at the root of issues some have faced during both initial startup, and for some during flight.
I'm of the opinion that the suggestion offered by Timinator to re-flash the f/w on both the AC as well as the RC while keeping the f/w versions of the two close to one another is always a good rule of thumb, and hopefully this will prevent any further occurrences of this nature.
Alternatively, you may want to simply continue to fly the model at a conservative distance, while monitoring your flight controls, until you feel more confident with overall performance. : )
Lastly, you may want to send it into DJI for their explanation as to what may have created the model to perform as it had.
I'm somewhat curious to learn from the other pilot who experienced a similar issue if a f/w update had recently occurred on either the AC or RC or even possibly a device being used, as well as the f/w versions used at the time of the incident, to get a better prospective of the issue.

One last thing I'd like to mention, and one which you probably are well aware of,
As a general rule, if you are one who use other flight apps from time to time eg. litchi etc. it's always best to ensure they are not running in the background on your device, as they may cause interference with overall flight operations. Turning on Airplane mode on your device can be helpful as well with preventing interference.

All the best!
 
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