Good afternoon all.  Newbie alert LOL..

Yesterday, while out on my 2nd flight with my MP, I started off with 16 sattelites and a strong "green" gps signal.  I flew around for approximately 12 minutes and all of a sudden I received a "weak GPS signal".  I was less then 500m from the set home point and 55m in the air.  Once I received the weak GPS signal, I immediately hit the "RTH" button and NOTHING happened.  Message says "weak GPS signal, homepoint lost".  Since this was my 2nd flight and first more then 100m away from me, I started to panic because the MP started to drift away from me even though the sticks were dead center.  Since I knew the general direction the MP was, I moved the stick forward and it started to come back but was acting strange in flight.  I have tried to research this but nothing comes up.  Anyone have a clue what could have happened?  I calibrated ALL sensors and have the updated firmware.  Using Iphone 6s and on airplane mode.  Everything is up to date.

The "obstacle avoidance" message was weird simply because I was over a swamp with absolutely no obstacles anywhere near me.

Daddy6466 Posted at 2018-4-14 09:08
The "obstacle avoidance" message was weird simply because I was over a swamp with absolutely no obstacles anywhere near me.

My thought here is that the compass errors being reported are conflicting with GPS data, the machine is then falling back to ATTI mode and will drift with the wind.

Were you flying near any large structures when this first appeared ?

If not then try a compass calibration in a suitable area outside, no ferrous objects, reinforced concrete (rebar strengthened) or power lines nearby.

I suggest you post your flight log here for someone to review and advise you. Seems that you encountered compass errors has pointed out by Aardvark above but the flight log will be more accurate.

http://www.phantomhelp.com/LogViewer/Upload/

Aardvark Posted at 2018-4-14 09:26
My thought here is that the compass errors being reported are conflicting with GPS data, the machine is then falling back to ATTI mode and will drift with the wind.

Were you flying near any large structures when this first appeared ?

Was in the middle of a bush area.  Tallest thing in the area were the trees at about 30 ft high.  

Suren Posted at 2018-4-14 10:11
I suggest you post your flight log here for someone to review and advise you. Seems that you encountered compass errors has pointed out by Aardvark above but the flight log will be more accurate.

http://www.phantomhelp.com/LogViewer/Upload/

Done.  Who looks at this now?

Daddy6466 Posted at 2018-4-14 11:38
Done.  Who looks at this now?

You have to share the upload link with us in order to allow us having a look at it ;-)

Wachtberger Posted at 2018-4-14 11:44
You have to share the upload link with us in order to allow us having a look at it ;-)

http://www.phantomhelp.com/LogViewer/KH70GAFMFS1QFZ0D0PO5/#

Daddy6466 Posted at 2018-4-14 11:59
http://www.phantomhelp.com/LogViewer/KH70GAFMFS1QFZ0D0PO5/#

I noticed a shat ton of yaw errors, and compass errors.  I calibrated this thing both flights.

Daddy6466 Posted at 2018-4-14 12:00
I noticed a shat ton of yaw errors, and compass errors.  I calibrated this thing both flights.

Yes, problems started at 8m 41.7s and quickly after it switched into ATTI mode. GPS link came back later but the same problems repeated. Very difficult to say what exactly has caused this, but there seems to have been some strong interference. Hopefully others will be able to tell you more.
But I am happy that you got your AC safely back!

Wachtberger Posted at 2018-4-14 12:11
Yes, problems started at 8m 41.7s and quickly after it switched into ATTI mode. GPS link came back later but the same problems repeated. Very difficult to say what exactly has caused this, but there seems to have been some strong interference. Hopefully others will be able to tell you more.
But I am happy that you got your AC safely back!

Weird that I got a proximity alert when I was over a flat swamp land with nothing even close.  I wonder if I should contact DJI support?

Daddy6466 Posted at 2018-4-14 12:18
Weird that I got a proximity alert when I was over a flat swamp land with nothing even close.  I wonder if I should contact DJI support?

Yes, that is always a good move. They can analyse much more than we are able to and the findings might help to make the device better or at least explain what has happened: https://www.dji.com/support
Open a formal support case. They will ask you to upload your blackbox data. You can export them with DJI Assistant.

Daddy6466 Posted at 2018-4-14 12:18
Weird that I got a proximity alert when I was over a flat swamp land with nothing even close.  I wonder if I should contact DJI support?

1/ obstacle is almost certainly the sun and is common in MP

2/ IMU heading exception is almost certainly coming from conflicting data between compass and IMU .
What happens in this situation is at take off compass is not on correct heading caused by some kind af magnetic interference most likely coming from take off position or close to it.

The best way I can explain this is. If you put your Aircraft on the ground in normal circumstances, start it up, then lift it up and turn it 90 degrees to the right both your compass heading and IMU will both move together 90 degrees and no problems.
If you put your Aircraft on the ground and there is magnetic interference only the heading of your compass will change, your aircraft will still take off. But when it clears magnetic interference compass will then move to correct heading which you would think was great. But No, what happens is IMU is then conflicted and confused because of this sudden movement by compass, so you receive IMU exceptional heading warning, your aircraft cannot deal with data conflict so decides to switch to Atti mode dropping gps in favour of compass simply because aircraft can fly without gps but not compass.

While I can’t be certain you picked up interference from the ground or surrounding area it is the most common cause.
I have seen many cases where people start their aircraft in or on their car in their house and then bring it outside so damage is already done and we will see exact same warnings and and reaction from aircraft.

We all should check our compass when we start our aircraft and maybe more of this could be avoided, you can do this by checking the small red triangle in the lower left corner of your telemetry.

One last thing I will say is we must always try to land aircraft immediately when this occurs.

Everyone is happy that your got your MP back safe and sound.  And I know how harrowing it is when your bird is doing something that you can't understand or control.  But I was snickering while I was looking at your screen prints at the beginning of your story.  Yes, I know that English is a second language for the designers and programmers at DJI, but "GPS signal too WEEK???"  7 days is a bit long for a bad signal.  Yes, English can be confusing for someone when it's a second language.  It's bad enough for us that were born into it.  LOL

Daddy6466 Posted at 2018-4-14 12:18
Weird that I got a proximity alert when I was over a flat swamp land with nothing even close.  I wonder if I should contact DJI support?

Also calibration of compass in bad area or simply a bad calibration will and can cause similar reaction.
There is no need to continue to calibrate your compass and it’s more likely you will get a bad calibration, if your compass is ok leave it alone period.

hallmark007 Posted at 2018-4-14 13:06
1/ obstacle is almost certainly the sun and is common in MP

2/ IMU heading exception is almost certainly coming from conflicting data between compass and IMU .

Thank you for this excellent analysis!

hallmark007 Posted at 2018-4-14 13:06
1/ obstacle is almost certainly the sun and is common in MP

2/ IMU heading exception is almost certainly coming from conflicting data between compass and IMU .

Great info on your assessment

hallmark007 Posted at 2018-4-14 13:06
1/ obstacle is almost certainly the sun and is common in MP

2/ IMU heading exception is almost certainly coming from conflicting data between compass and IMU .

1- It was overcast so no sun anywhere to be seen.
2- IMU calibration AND compass calibration was done 30 seconds prior to liftoff AND was in a bushy are with ZERO magnetic interferance.  I have seen my MP spit out codes to that effect when I first got it and tried to calibrate in my house but after 2nd IMU/Compass calibration outside, there was no messages and 100% green GPS signal at take off AND at the furthest distance away.  It wasn't untill I was returning to my position manually that this started to happen.  
Send flight records to DJI for analysis.  Want to hear their side of the story.  Will post their response once I receive it.

hallmark007 Posted at 2018-4-14 13:21
Also calibration of compass in bad area or simply a bad calibration will and can cause similar reaction.
There is no need to continue to calibrate your compass and it’s more likely you will get a bad calibration, if your compass is ok leave it alone period.

99% of posts and videos state "Calibrate your compass EVERY flight" to avoid any issues with RTH.  Not sure if you have seen the same posts or videos.

Daddy6466 Posted at 2018-4-15 03:09
99% of posts and videos state "Calibrate your compass EVERY flight" to avoid any issues with RTH.  Not sure if you have seen the same posts or videos.

No they don’t and if they do there wrong, it’s impossible to make a good compass better by calibration, but it’s very easy to make a good compass bad. Once you have a good compass and you have checked it prior to flight leave it. If you get a message telling you to move or calibrate always shut down and move NEVER calibrate in this location, for obvious reasons this is the area with interference. There are many areas with underground cables metal objects buried etc.

I have 5 dji aircraft and in all the time I’ve had them I have only calibrated a handful of times,


Calibration gives the compass the information it needs to determine which magnetic influences are part of the MavAir and what is the earth's normal magnetic field.
The compass doesn't lose calibration and doesn't ever need re-calibration unless you add or remove equipment to/from the MavAir.

Daddy6466 Posted at 2018-4-15 03:07
1- It was overcast so no sun anywhere to be seen.
2- IMU calibration AND compass calibration was done 30 seconds prior to liftoff AND was in a bushy are with ZERO magnetic interferance.  I have seen my MP spit out codes to that effect when I first got it and tried to calibrate in my house but after 2nd IMU/Compass calibration outside, there was no messages and 100% green GPS signal at take off AND at the furthest distance away.  It wasn't untill I was returning to my position manually that this started to happen.  
Send flight records to DJI for analysis.  Want to hear their side of the story.  Will post their response once I receive it.

This link will help much better than continually trying to calibrate your compass.

https://forum.dji.com/forum.php? ... &fromuid=260008

hallmark007 Posted at 2018-4-15 05:58
This link will help much better than continually trying to calibrate your compass.

https://forum.dji.com/forum.php?mod=viewthread&tid=104222&fromuid=260008

Great information.  I wonder why alot of people say to calibrate compass every time  you fly?  Also, DJI and  most information out there says to raise the drone to 10m in order to get a good RTH location.  What are your thoughts on that one?  I will follow your instructions on the start up proceedure on the link.  Also, should I calibrate my compass one last time?  I am wondering if I have a bad calibration now and need to recalibrate?  

hallmark007 Posted at 2018-4-15 05:53
No they don’t and if they do there wrong, it’s impossible to make a good compass better by calibration, but it’s very easy to make a good compass bad. Once you have a good compass and you have checked it prior to flight leave it. If you get a message telling you to move or calibrate always shut down and move NEVER calibrate in this location, for obvious reasons this is the area with interference. There are many areas with underground cables metal objects buried etc.

I have 5 dji aircraft and in all the time I’ve had them I have only calibrated a handful of times,

Not sure if this matters but I have the MP not MA

Daddy6466 Posted at 2018-4-15 06:18
Not sure if this matters but I have the MP not MA

its the very same for all aircraft.