RTH initiated while P3P was on the ground resulting in crash

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Very interesting thread. Now I'm gonna have to try and duplicate this issue. I'll land (away from the home point) and then initiate RTH and see if it auto takes off and comes home. I suppose it makes sense that RTH will still work if the AC motors are idling after landing somewhere distant. Any situation that would normally initiate RTH should still work even from the ground.
Make sure you land on a reinforced driveway.
 

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Yeh I find it hard to believe reber in concrete driveways does anything,I have never had any issue regarding steel in concrete, I dont have proof but I always see this term as a excuse, some will disagree but it's what I have experienced over the years
@3rdof5 remember he had left stick down at time this happen,,please dont stratch your drone and be careful
 
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Yeh I find it hard to believe reber in concrete driveways does anything,I have never had any issue regarding steel in concrete, I dont have proof but I always see this term as a excuse, some will disagree but it's what I have experienced over the years
@3rdof5 remember he had left stick down at time this happen,,please dont stratch your drone and be careful
I realize he had left stick down. That shouldn't have created any issues. Even on a critical battery landing, as coming down and stopping the motors always uses less current than hovering or flying. It should have simply landed and shut down. A compass error at that point should not have triggered anything. Clearly "something" triggered RTH but I can't imagine anything, even accidentally, triggering it. I will definitely investigate this (carefully) with my P3P.
 
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Without the flight records, no one will know and it is just speculation.

I came close to the metal roof of my house and my P3 started making big broad circles. Very hard to control and crashed into tall grass. The grass was about two feet high. Great stuff to crash into. I was wondering if how the driveway was built makes a difference. Some use a heavy metal wire and some use rebar which is much heavier. I remember one story on this forum, where a guy took off from a fire department driveway. His drone made big uncontrollable circles and crashed into the building. I never take off from concrete. All of this may have nothing to do with this incident. Flight records please, so we all can learn and help other also.
 
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Without the flight records, no one will know and it is just speculation.

I came close to the metal roof of my house and my P3 started making big broad circles. Very hard to control and crashed into tall grass. The grass was about two feet high. Great stuff to crash into. I was wondering if how the driveway was built makes a difference. Some use a heavy metal wire and some use rebar which is much heavier. I remember one story on this forum, where a guy took off from a fire department driveway. His drone made big uncontrollable circles and crashed into the building. I never take off from concrete. All of this may have nothing to do with this incident. Flight records please, so we all can learn and help other also.
Oh I couldn't agree more that taking off from rebar reinforced concrete can and usually does cause compasd errors, I've seen proof. But during landing with left stick down I seriously doubt it would have contributed to this issue.
 
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Oh well looks like OP not coming back,,,can see this thread being shut down but befor it does wont a magnetic field interference prompt in red appear at top of screen if interference from concrete steel or is this different than a compass error move and calibrate or are these 2 the same,,this is why I say driveway steel cant really do that because alert will show immediately before take off or landing ,,does that sound right or does my brain need de gassing to function right again,,,,I understand large steel surface would cause but again there be a prompt,,,no prompt from a driveway mean no issues,,,,this just my thought on this ,hey if a magnetic sticks to the drive,yeh sure expect a issue,,,I can handle being told otherwise so let me have it...test is easy ,,open app on compass and see if numbers going crazy between there limits
 
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Very interesting thread. Now I'm gonna have to try and duplicate this issue. I'll land (away from the home point) and then initiate RTH and see if it auto takes off and comes home. I suppose it makes sense that RTH will still work if the AC motors are idling after landing somewhere distant. Any situation that would normally initiate RTH should still work even from the ground.
you are a prophet, man hopfully you post your findings when you experiment.
 
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you are a prophet, man hopfully you post your findings when you experiment.
Lol thanks. I definitely will report back with my findings when I can get to a place to fly legally. I can't at home, at least not far enough and on rebar concrete to find out. This weekend hopefully!
 
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Oh well looks like OP not coming back,,,can see this thread being shut down but befor it does wont a magnetic field interference prompt in red appear at top of screen if interference from concrete steel or is this different than a compass error move and calibrate or are these 2 the same,,this is why I say driveway steel cant really do that because alert will show immediately before take off or landing ,,does that sound right or does my brain need de gassing to function right again,,,,I understand large steel surface would cause but again there be a prompt,,,no prompt from a driveway mean no issues,,,,this just my thought on this ,hey if a magnetic sticks to the drive,yeh sure expect a issue,,,I can handle being told otherwise so let me have it...test is easy ,,open app on compass and see if numbers going crazy between there limits
@Meta4 what do you make of my thoughts here,,I know your always good with compass issues,,
Am I just crazy thinking this....this what bug me,even landing in such a location wouldn't this come up onscreen or is this message the same as getting a compass error move and calibrate,,,I know I'm good at asking awkward stuff
Screenshot_20200922-203744_Chrome.jpg
 
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@Meta4 what do you make of my thoughts here,,I know your always good with compass issues,,
Am I just crazy thinking this....this what bug me,even landing in such a location wouldn't this come up onscreen or is this message the same as getting a compass error move and calibrate,,,I know I'm good at asking awkward stuff
It looks like you've done the drone on the car roof test

The steel deflects the compass much more than the earth's magnetic field would and as a result, the compass warns you of a problem.

A bigger problem is when the drone is launched from close to a smaller steel item, it could just be a nail or screw in a wooden deck (if it's close enough to the compass) or something larger and further away.
It the deflection of the compass is of a similar strength to the earth's magnetic field but at a different direction, there will be no warning.
But the deflected compass reading will be used to initialise the mag_yaw values of the IMU gyro sensors.
When the drone launches and the compass is no longer affected by the steel, that's when the serious yaw error situation starts (and it usually ends badly).

Here is an illustration of why you could launch from a concrete surface 20 times without a problem, but it might give problems the next time.

You don't know the thickness of the concrete or where the thicker bars or overlapped mesh panels are.
If your compass is close enough to a large enough mass of steel, all bets are off.
And just an inch or two difference in placing the drone is all it might take.

I can't see how a concrete surface would cause the OP's problem and my best guess without data is a low battery RTH or he turned off the controller triggering Failsafe RTH.
Both have been seen many times before.
Maybe he'll come up with his data to clear up what really happened?
 
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It looks like you've done the drone on the car roof test

The steel deflects the compass much more than the earth's magnetic field would and as a result, the compass warns you of a problem.

A bigger problem is when the drone is launched from close to a smaller steel item, it could just be a nail or screw in a wooden deck (if it's close enough to the compass) or something larger and further away.
It the deflection of the compass is of a similar strength to the earth's magnetic field but at a different direction, there will be no warning.
But the deflected compass reading will be used to initialise the mag_yaw values of the IMU gyro sensors.
When the drone launches and the compass is no longer affected by the steel, that's when the serious yaw error situation starts (and it usually ends badly).

Here is an illustration of why you could launch from a concrete surface 20 times without a problem, but it might give problems the next time.

You don't know the thickness of the concrete or where the thicker bars or overlapped mesh panels are.
If your compass is close enough to a large enough mass of steel, all bets are off.
And just an inch or two difference in placing the drone is all it might take.

I can't see how a concrete surface would cause the OP's problem and my best guess without data is a low battery RTH or he turned off the controller triggering Failsafe RTH.
Both have been seen many times before.
Maybe he'll come up with his data to clear up what really happened?
Ok thank you for explaining that to me,,no not my picture(phantom help)just my example,,been driving me crazy for some reason so yes hope he comes back,,thanks again for that;)
 
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It looks like you've done the drone on the car roof test

The steel deflects the compass much more than the earth's magnetic field would and as a result, the compass warns you of a problem.

A bigger problem is when the drone is launched from close to a smaller steel item, it could just be a nail or screw in a wooden deck (if it's close enough to the compass) or something larger and further away.
It the deflection of the compass is of a similar strength to the earth's magnetic field but at a different direction, there will be no warning.
But the deflected compass reading will be used to initialise the mag_yaw values of the IMU gyro sensors.
When the drone launches and the compass is no longer affected by the steel, that's when the serious yaw error situation starts (and it usually ends badly).

Here is an illustration of why you could launch from a concrete surface 20 times without a problem, but it might give problems the next time.

You don't know the thickness of the concrete or where the thicker bars or overlapped mesh panels are.
If your compass is close enough to a large enough mass of steel, all bets are off.
And just an inch or two difference in placing the drone is all it might take.

I can't see how a concrete surface would cause the OP's problem and my best guess without data is a low battery RTH or he turned off the controller triggering Failsafe RTH.
Both have been seen many times before.
Maybe he'll come up with his data to clear up what really happened?
just to make sure i got you correctly!!now in general the p3p cannot take off even in atti mode until compass error goes away (you change take off location) right??
now lets consider the p3p was armed but after that it got magnetic interference while still on ground and so the motors are now already running , so you can take off but you are saying in this case the craft imu will save the "heading" according to this error, now here is the big question??
in case the interference continues and you lose rc link a fly away will happen, most probably??
in case while you armed then got interference but you hover or fly for a while and interference goes away the compass gets back to order but why the p3p wont update the new compass calculations to the p3p imu???
 
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Ok cmon back @Waynosan ,we need your data to put us out of this misery,,since you not replyed to nothing I'm going to say pilot error and he wants no one to know,,nothing to be ashamed about ,its called learning so cmon back ,,your post as you can see almost getting us in trouble with backwards and foward guessing,,,why did you post this if your not following it,should delete the whole thread so we all saved from this fairytale
 
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just to make sure i got you correctly!!now in general the p3p cannot take off even in atti mode until compass error goes away (you change take off location) right??
now lets consider the p3p was armed but after that it got magnetic interference while still on ground and so the motors are now already running , so you can take off but you are saying in this case the craft imu will save the "heading" according to this error, now here is the big question??
in case the interference continues and you lose rc link a fly away will happen, most probably??
in case while you armed then got interference but you hover or fly for a while and interference goes away the compass gets back to order but why the p3p wont update the new compass calculations to the p3p imu???
I didn't say what you think I said.
Maybe reading post #31 again will help.
 
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Hi guys,
Thanks for all the feedback. Sorry to keep some y'all waiting but I have other stuff going on in my life so thanks for your understanding.

The driveway the P3P landed on was gravel, no rebar under it. Landing point was also higher then the take-off point which someone above speculated may have been the issue. The thing is that if I'm pressing down on the left stick and it senses that it's not decreasing in altitude then shouldn't it know that it's on the ground? Here are some damage photos and I'll upload the logs momentarily (reading how to do it now).

The lens from the camera is an easy replacement. I noticed one of the diffusers is gone but that's not a big deal. The ribbon cable is obviously ripped so that needs to be replaced. The part I'm most worried about is the gimbal arm, there's now friction between it and the lower silver housing so maybe the y-axis gimbal motor also needs replacement?


Update: here's the log log link: DJI Flight Log Viewer - PhantomHelp.com
 

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I landed the P3P in a few dozen feet from where it took off - on a more level part of my relatives' driveway instead of the street. As un-luck would have it, even thought it was on the ground and I was pushing down the throttle stick it initiated RTH home. I have no idea why it decided to do that when it was already on the ground for several seconds
The data shows that you brought the drone down and held the left stick full down from 18:21 to 18:22.7.
But at 18:21.8, before the motors had shut down (that takes 3 seconds), Low Power RTH initiated with the battery at 17%.
The drone climbed to 42 feet where it crashed and fell.
It looks like a case of bad timing in the wrong location.

For future reference, the fastest way to cancel any automated flight like RTH is to quickly flick the flight mode switch out of P-GPS and back again.
 

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Hi guys,
Thanks for all the feedback. Sorry to keep some y'all waiting but I have other stuff going on in my life so thanks for your understanding.

The driveway the P3P landed on was gravel, no rebar under it. Landing point was also higher then the take-off point which someone above speculated may have been the issue. The thing is that if I'm pressing down on the left stick and it senses that it's not decreasing in altitude then shouldn't it know that it's on the ground? Here are some damage photos and I'll upload the logs momentarily (reading how to do it now).

The lens from the camera is an easy replacement. I noticed one of the diffusers is gone but that's not a big deal. The ribbon cable is obviously ripped so that needs to be replaced. The part I'm most worried about is the gimbal arm, there's now friction between it and the lower silver housing so maybe the y-axis gimbal motor also needs replacement?


Update: here's the log log link: DJI Flight Log Viewer - PhantomHelp.com
Sorry for saying your fault but now we know and I'm sorry for that,,and seems bad luck found it..certainly seems dam crazy thing to happen,,you would think the drone can sense it got low battery and stay put on the ground as auto land does but to take off back to rth seems rather dangerous on the part of dji,it know it cant make it back to home point so why it take off ? Artificial intelligence been drinking,,I had a rth over a mile out at 50% and cause it thought it wont make it back it started to automatically landing and finally able to cancel with multiple press on the onscreen prompt to cancel,,so called smart battery for you and bad software design,,why the drone throws these out when it knows already where it is a bad one to the pilot ,,mine scared the grey hair off my head and that no fun
 
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Fascinating story and one to serve as a warning to us fliers!
Am I reading the flight correctly that you took off from Bluff Lane and then walked onto the driveway of the house seen with the red and white cars parked up, which is about five feet higher than Bluff Lane.
Definitely RTH activated by low battery @18.21.8 but I wonder why it overrode your shut-down signal from the LH stick?
 
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The data shows that you brought the drone down and held the left stick full down from 18:21 to 18:22.7.
But at 18:21.8, before the motors had shut down (that takes 3 seconds), Low Power RTH initiated with the battery at 17%.
The drone climbed to 42 feet where it crashed and fell.
It looks like a case of bad timing in the wrong location.

For future reference, the fastest way to cancel any automated flight like RTH is to quickly flick the flight mode switch out of P-GPS and back again.

I didn't know about the flight mode switch cancel, it all happened very fast and I was kind of in shock for a moment why the heck it started bolting upward and by the time I got my finder on the phone it was too late. The switch cancel may have saved me but ultimately my portion of the blame lays in the fact that I didn't make sure NOT to fly it under any obstructions. I seem to recall also trying to stop the motors by pressing both sticks down and inward but I didn't see that in the dataset so perhaps that was during an earlier flight. Would have been nice if the DJI SW kept it on the ground though instead of initiating RTH. Oh well, lesson learned and hopefully it will keep other from making the same mistake.
 

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