http://www.phantomhelp.com/LogViewer/W8KYT1SKRJEORRDBDG12/
Can someone tell me what happen , i went there could not search for my drone .....

First your compass gone crazy(compass error) It must been stuck or catch strong magnetic fields in that area. Yaw Error means the copter can´t rotate on point. And the speed error was in ATTI,it´s a miss match between the real speed and the GPS taken speed,i think.I hope you find your bird soon.

Peterx Posted at 2018-3-18 09:03
First your compass gone crazy(compass error) It must been stuck or catch strong magnetic fields in that area. Yaw Error means the copter can´t rotate on point. And the speed error was in ATTI,it´s a miss match between the real speed and the GPS taken speed,i think.I hope you find your bird soon.

should i keep searching in that area?

Let me take a wild guess, you calibrated the compass before taking off.

Look around the last known place where the bird hovered or flied.

i have went the last location shown , but can't found my drone .... what should i do

AY Posted at 2018-3-18 10:02
i have went the last location shown , but can't found my drone .... what should i do

You can't find it there because it was travelling away at speed when it lost signal.
You launched with a half flat battery so it's not possible to know how far it might have gone.
The compass error soon after launch followed by yaw error suggests that you launched from a steel or reinforced concrete surface.

I understand that the compass is important, but if GPS is working, I would think it would be smart enough to do a RTH by seeing if it is moving closer or farther from the home point location coordinates. IMO a failed compass alone should not result in a fly away.  Heck, it even tracks distance, so it should also be able to fly in a direction that results in that value decreasing.  I see no technical reason why it couldn't.

Right after startup did you hear it tell you that the "home point has been updated, please check it on the map" and if so did you confirm it had been on your mobile device? Another thing is did you have it set to RTH or hover in the app?

No, i did not hear home point have been updated, i use manual S2 button to RTH ... but it was unable to return ... then i try to follow to GPS show on the map look for the drone ... but spent 3 hr cant look for it

Texas-Mark Posted at 2018-3-18 11:36
I understand that the compass is important, but if GPS is working, I would think it would be smart enough to do a RTH by seeing if it is moving closer or farther from the home point location coordinates. IMO a failed compass alone should not result in a fly away.  Heck, it even tracks distance, so it should also be able to fly in a direction that results in that value decreasing.  I see no technical reason why it couldn't.

I don't understand the science part of it either but what I learned here is when compass and GPS don't agree with each other the system shuts down GPS by going into Atti mode.
Apparently with GPS alone the aircraft can't go home. With compass alone it can.

It really shouldn't have even started up. With that many compass warnings, I guess you were just unlucky in this case it did.  Always heed what it's telling you.  Some don't mean anything serious, others can result in this happening.   

Eric13 Posted at 2018-3-18 12:17
I don't understand the science part of it either but what I learned here is when compass and GPS don't agree with each other the system shuts down GPS by going into Atti mode.
Apparently with GPS alone the aircraft can't go home. With compass alone it can.

Not sure how it could get home with compass alone. Sure, it might be able to go in the correct general direction, but then what?  How does it know how far to go?  Just seems that GPS is a lot more reliable and accurate, and if a conflict arises, it should choose GPS. Even my archaic car GPS can figure out the direction it is going with GPS alone.  Once you start moving, it's a simple matter to determine direction.  Not sure why DJI does it the way they do, just saying it can be done with GPS alone as long as you are moving.

Texas-Mark Posted at 2018-3-18 12:35
Not sure how it could get home with compass alone. Sure, it might be able to go in the correct general direction, but then what?  How does it know how far to go?  Just seems that GPS is a lot more reliable and accurate, and if a conflict arises, it should choose GPS. Even my archaic car GPS can figure out the direction it is going with GPS alone.  Once you start moving, it's a simple matter to determine direction.  Not sure why DJI does it the way they do, just saying it can be done with GPS alone as long as you are moving.

I think the same way like you. Just wait a little and Labroides or others will explain.
There must be a reason why the system shuts down GPS and not compass.
By intuition I would thing compass should be shut down - but hey: What the heck do I know ;-)

Eric13 Posted at 2018-3-18 12:46
I think the same way like you. Just wait a little and Labroides or others will explain.
There must be a reason why the system shuts down GPS and not compass.
By intuition I would thing compass should be shut down - but hey: What the heck do I know ;-)

For most of that flight the system was in P-GPS mode and had ample stellites. But it was experiencing continuous compass errors. It did try to go home at the very end, but the flight record ends. I suspect, like others, that you launched from a surface that contained metal. But in any event, you probably could not have picked a worse place to fly from, as the university and surrounding area would have had intense and saturated coverage of WiFi routers.

I lost my P3 SE due to a drone malfunction.  DJI replaced it.  So you should email to support@dji.com.

They can asses if your drone malfunctioned or it was the dreaded Pilot error.   

https://forum.dji.com/thread-125209-1-1.html

Texas-Mark Posted at 2018-3-18 11:36
I understand that the compass is important, but if GPS is working, I would think it would be smart enough to do a RTH by seeing if it is moving closer or farther from the home point location coordinates. IMO a failed compass alone should not result in a fly away.  Heck, it even tracks distance, so it should also be able to fly in a direction that results in that value decreasing.  I see no technical reason why it couldn't.

Without a correct compass the drone wont know where it is to RTH.

I looked at your logs and you got warnings very early in the flight.  You should have landed rather than kept flying with all the warnings popping up.  You can load your log into google earth which would only give you an idea of where your drone was when it had last contact.

Seems you were flying over an open field.

blackcrusader Posted at 2018-3-18 18:12
Without a correct compass the drone wont know where it is to RTH.

It has the RTH GPS coordinates.  As I noted it's not difficult to calculate your heading with GPS coordinates while moving.   As I also noted, I have older GPS devices that have no compass, but yet they will give you a compass heading based on the changes in GPS data.

Now I know that is not what they are doing. My point was that it is technically fairly easy to extrapolate your heading with GPS data as long as the drone is moving.

A word of advise, If in the future, if a warning pops up and you are in sight of your bird, bring it in asap. I mean heck no gps no compass, hell something dreadfull is about to happen. Good luck and warning are thier for a reason....

I went over your flight info, Let me ask you a question. Why did you keep flying when you kept on jumping in and out of pgps to atti mode. I mean dude, from that point i would of abort the flight. Or were you just curious of what would happen?!!! YOUR speed and altitude were very slow and low from the gate for quiet some time. You had plenty of time to recover the bird once the first signs of trouble.  Good luck. And  If you fly again I hope you do cause its a blast Any concrete slabs are a big NO NO!!! I dont meant to come at you hard its just these drones are not like cheap or anything. best of luck.>>>

Texas-Mark Posted at 2018-3-18 11:36
I understand that the compass is important, but if GPS is working, I would think it would be smart enough to do a RTH by seeing if it is moving closer or farther from the home point location coordinates. IMO a failed compass alone should not result in a fly away.  Heck, it even tracks distance, so it should also be able to fly in a direction that results in that value decreasing.  I see no technical reason why it couldn't.

the compass is important, but if GPS is working, I would think it would be smart enough to do a RTH by seeing if it is moving closer or farther from the home point location coordinates.
You would think that but it's not how the Phantom works.
The Phantom can fly without GPS but it can't fly straight without knowing which way it's pointing.
And in this incident, it's worse because the compass is giving the flight controller incorrect information so when it tries to fly where it should, it appears to go crazy.
It turns but never reaches the compass course it's looking for.

Michgolden Posted at 2018-3-18 12:08
Right after startup did you hear it tell you that the "home point has been updated, please check it on the map" and if so did you confirm it had been on your mobile device? Another thing is did you have it set to RTH or hover in the app?

You have to be very fast and impatient to launch before the Phantom records a home point.
In this case, (like most) the home point was recorded before flight.
But even if it wasn't that wouldn't have made any difference.
Flying without a home point doesn't make the Phantom zip away on its own.
The Loss of Signal option also would have made no difference.

flyhigh69 Posted at 2018-3-18 20:17
I went over your flight info, Let me ask you a question. Why did you keep flying when you kept on jumping in and out of pgps to atti mode. I mean dude, from that point i would of abort the flight. Or were you just curious of what would happen?!!! YOUR speed and altitude were very slow and low from the gate for quiet some time. You had plenty of time to recover the bird once the first signs of trouble.  Good luck. And  If you fly again I hope you do cause its a blast Any concrete slabs are a big NO NO!!! I dont meant to come at you hard its just these drones are not like cheap or anything. best of luck.>>>

Why did you keep flying when you kept on jumping in and out of pgps to atti mode. I mean dude, from that point i would of abort the flight.
He didn't have much of a chance.
The Phantom wasn't sitting there waiting for a command.
It was zipping around doing crazy stuff.

Texas-Mark Posted at 2018-3-18 18:38
It has the RTH GPS coordinates.  As I noted it's not difficult to calculate your heading with GPS coordinates while moving.   As I also noted, I have older GPS devices that have no compass, but yet they will give you a compass heading based on the changes in GPS data.

Now I know that is not what they are doing. My point was that it is technically fairly easy to extrapolate your heading with GPS data as long as the drone is moving.

See this. A pretty good explanation.
The poster also said earlier in this thread in a tricky environment he would start in Atti from the beginning and important is to have Smart RTH turned off.

https://phantompilots.com/threads/looking-for-trouble.88247/page-2#post-915176

Eric13 Posted at 2018-3-19 00:56
See this. A pretty good explanation.
The poster also said earlier in this thread in a tricky environment he would start in Atti from the beginning and important is to have Smart RTH turned off.

The poster also said earlier in this thread in a tricky environment he would start in Atti from the beginning
He was wrong.
People confuse GPS and compass.
Starting in atti mode means the flight controller ignores GPS data .... but it still has to deal with compass data.
He was talking about a simple compass error.
The incident that the OP had to deal with was a lot more difficult.
He found himself with a yaw error that didn't just go away when the Phantom gets further away from the cause of the problem.
Post #27 in that same thread explains the details of what the yaw error problem is.