Phantom Rain : Magnetic Interference is the Phantom Killer in disguise:

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Here is the final answer from DJI for the difference between P4P 1.0 and 2.0. In conclusion, my P4P v2.0 is working as it should.
Screenshot_20181127-162910_Outlook.jpg
 

sar104

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Here is the final answer from DJI for the difference between P4P 1.0 and 2.0. In conclusion, my P4P v2.0 is working as it should.
View attachment 105721

Thanks for posting that. It seems that the P4P Pro has similar firmware controls as the Mavic 2. It's disappointing though - the 30 day calibration may be somewhat defensible on the basis that the magnetic field of the aircraft may change over time if it is exposed to strong magnetic fields, but the 50 km requirement is just silly - I cannot see any scientific basis for that at all. They had stopped even advising recalibration when changing location for most models, so this is not even a consistent requirement.
 
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Thanks for posting that. It seems that the P4P Pro has similar firmware controls as the Mavic 2. It's disappointing though - the 30 day calibration may be somewhat defensible on the basis that the magnetic field of the aircraft may change over time if it is exposed to strong magnetic fields, but the 50 km requirement is just silly - I cannot see any scientific basis for that at all. They had stopped even advising recalibration when changing location for most models, so this is not even a consistent requirement.
Please remember that the magnetic waves change from area to area. What I assume DJI is trying to prevent is future fly aways due to compass misreadings.
 

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Please remember that the magnetic waves change from area to area. What I assume DJI is trying to prevent is future fly aways due to compass misreadings.

Ah yes - that old misunderstanding again. The earth's field changes in strength, declination and inclination, but the compass calibration doesn't measure those - it's sole purpose is to determine the aircraft's magnetic field so that it can subtract it from the total measured field in flight. In particular the declination, which is the difference between magnetic north and true north, and is needed in order to relate the compass reading to the aircraft heading in the true north frame of reference, cannot be measured by any calibration method and is instead computed by the FC from a global magnetic field model in the firmware.
 
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Ah yes - that old misunderstanding again. The earth's field changes in strength, declination and inclination, but the compass calibration doesn't measure those - it's sole purpose is to determine the aircraft's magnetic field so that it can subtract it from the total measured field in flight. In particular the declination, which is the difference between magnetic north and true north, and is needed in order to relate the compass reading to the aircraft heading in the true north frame of reference, cannot be measured by any calibration method and is instead computed by the FC from a global magnetic field model in the firmware.
If you put it that way, then DJI just wants you to do the calibration dance, just to amuse themselves. Everytime you get “calibrate your compass” they go “look look at the idiot doing the dance” and laugh about it. They have to balance their lives. They grew tired of the idiots who called to blame DJI for their crashes and took revenge.
 

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If you put it that way, then DJI just wants you to do the calibration dance, just to amuse themselves. Everytime you get “calibrate your compass” they go “look look at the idiot doing the dance” and laugh about it. They have to balance their lives. They grew tired of the idiots who called to blame DJI for their crashes and took revenge.

There may well be an element of DJI just trying to cover themselves. The main compass issue, caused by taking off from a location with magnetic interference which results in the IMU yaw being initialized to the wrong value, is a difficult one for them to deal with. It's kind of pilot error but DJI has never provided useful advice on how to avoid it, even though there is a relatively simple and robust solution. In my opinion they would be better served simply advising everyone to check that the aircraft orientation arrow is pointed in the correct direction on the map before taking off. That simple check would have prevented the vast majority of the loss of control cases reported on this forum and the Mavic forum.
 
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There may well be an element of DJI just trying to cover themselves. The main compass issue, caused by taking off from a location with magnetic interference which results in the IMU yaw being initialized to the wrong value, is a difficult one for them to deal with. It's kind of pilot error but DJI has never provided useful advice on how to avoid it, even though there is a relatively simple and robust solution. In my opinion they would be better served simply advising everyone to check that the aircraft orientation arrow is pointed in the correct direction on the map before taking off. That simple check would have prevented the vast majority of the loss of control cases reported on this forum and the Mavic forum.
I am no expert, but I have seen with my own eyes how interference with the compass has caused my phantom to fly away, twice. I can complete my mision, be on my way returning home then the bird steers left on it’s own and flies away at full speed. It is a scary few milliseconds while I switch to ATTI and regain control. Ever since I do recalibration of the compass (even if it does it no favors), I haven’t had any more flyaways.
 

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I am no expert, but I have seen with my own eyes how interference with the compass has caused my phantom to fly away, twice. I can complete my mision, be on my way returning home then the bird steers left on it’s own and flies away at full speed. It is a scary few milliseconds while I switch to ATTI and regain control. Ever since I do recalibration of the compass (even if it does it no favors), I haven’t had any more flyaways.

That description is hard to diagnose, but doesn't sound like a mis-calibrated compass - that should show up as soon as you start to fly. The same goes for magnetic interference at the takeoff point. I'd suggest that you take a look at the flight log - all the data needed to diagnose any compass issues are in the logs.
 
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That description is hard to diagnose, but doesn't sound like a mis-calibrated compass - that should show up as soon as you start to fly. The same goes for magnetic interference at the takeoff point. I'd suggest that you take a look at the flight log - all the data needed to diagnose any compass issues are in the logs.
The only different factor in that specific flight was a 50 Kw generator being turned on. I know for a fact that generators emit a magnetic field of considerable size, since I’ve seen how it affects the compass before taking off near one.

Edit: My point is, that when you calibrate, perhaps the drone takes into consideration any interference in the area and adjusts it’s math to consider this variable. Please bare in mind that I am no expert and am simply guessing.
 

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The only different factor in that specific flight was a 50 Kw generator being turned on. I know for a fact that generators emit a magnetic field of considerable size, since I’ve seen how it affects the compass before taking off near one.

It's just speculation without the data. The magnetic field from a generator is not going to extend more than a few meters at most.
 
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It's just speculation without the data. The magnetic field from a generator is not going to extend more than a few meters at most.
Edited my post above to finally say what I wanted to transmit. :p
 

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The only different factor in that specific flight was a 50 Kw generator being turned on. I know for a fact that generators emit a magnetic field of considerable size, since I’ve seen how it affects the compass before taking off near one.

Edit: My point is, that when you calibrate, perhaps the drone takes into consideration any interference in the area and adjusts it’s math to consider this variable. Please bare in mind that I am no expert and am simply guessing.

You have to think more in terms of what the compass is measuring. All it sees is the magnetic field, as a 3-dimensional vector, at the location of the aircraft. How do you think that it is going to know what is the earth's magnetic field and what is interference, unless the interference is very strong? And if the interference is strong, all it can know is that something is interfering, i.e. the total magnetic field is too strong or too weak or the inclination is wrong to be the earth's alone - there is no way for it to measure the interference directly. That prompts a magnetic interference warning (the ambiguous "move or calibrate" notice). Calibrating is pointless in the presence of interference because it cannot separate it from the earth's field. The compass simply cannot function in the presence of interference - there is no math to adjust that will compensate for it.
 
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I think the point being made is that the Atti mode error warming is of significant concern - more so than the magnetic interference. Introducing a magnetic field causes Atti errors, however, due to the way the software is written it only shows up once and won't show up again even though the problem persists.
So, when taking off, watch the screen carefully and not the drone, if you see Atti mode problems - land right away.
 
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Recently I caught myself making a Mistake that most likely I have been making On every single flight I have taken over the last 2 years.

In those last 2 years I have had two fly aways and each one DJI refunded me with 100% coupon for a brand new drone and that is great but the fault was most likely mine.

I recently had a Revelation of sorts that I take my eyes off of the Display to watch my drone take off into the sky for the first couple minutes and in doing so miss any error messages that might have popped on the screen such as Compass error / Magnetic Interference errors to name a few.

This could explain how I missed the critical errors that might have saved me from a fly away right on take off.

I have tried to break this habbit but it is very difficutl as my eyes just want to watch that take off as the drone is so close.

Obviously we are more at risk than most as we fly from some really bad advantage points , so I made this video to show how dangerous it can be to miss the Flash or an error message come across the screen especially at take off.

The video shows how little Magnetic Interference it takes to put your Drone in Jeopardy of a Fly Away and how deceiving it can be to continue to fly.

When it comes to magnetic Interference , it can take many forms, Compass error / Yaw Errors / Atti Mode.
The best advice I can share is do not trust your drone to fly after you get an error no matter how fast it appears on the screen, as the damage is most likely already done.

Best to shutdown , move your take off position and start again.

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I teach my students after the drone takes off to let it settle at the auto take off height of about 5 feet then inspect the drone, and check the controls and then the monitor for warnings. I guess that is the value of an education. Plus no fly aways, great video I'll be sure to use this article in my class.
 
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I haven't calibrated my compass in years. I understand that my P3P may be different than the P4P v2, but I'm guessing that the compass isn't different as much as it is the software, written by DJI, then sits in the same barrel with their "do the calibration dance" advice (cover their behind).

If you have compass interference, it's not an "Atti error", it's a message telling you that you are going into ATTI mode (which is not an error) because there is no GPS lock (due to magnetic interference in this case). You should be able to fly in ATTI mode (and I would switch off P mode at that point to keep the compass from interfering with flight logic; hence, no flyaways), but landing is probably a good idea in many-to-most cases so you can move your take off point.

I've taken off at points where, no matter what I do, I just can't get control of the craft out of ATTI mode, so I fly manually and usually land to change my take off point. However, at the new location, if I get no magnetic interference, I do not receive compass errors or calibration messages AND the flight goes just fine, without calibration. And another year goes by with good flights and no compass problems.

Chris
 
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Just a couple of thoughts, seeing errors while you are flying is difficult at best but you may be already be using these. I use both GO and Litchi to fly depending upon what I need at the moment, Litchi allows you to record screen so you can go back and see everything that goes across the screen. And I download all flights to Airdata Uav that allows you to access all of your flight data and technical data. I have put over 200 miles on a p4p and I wouldn’t go without these 2 programs. I personally have not had to recalibrate compass or mmu in all those miles. Good luck
 
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Recently I caught myself making a Mistake that most likely I have been making On every single flight I have taken over the last 2 years.

In those last 2 years I have had two fly aways and each one DJI refunded me with 100% coupon for a brand new drone and that is great but the fault was most likely mine.

I recently had a Revelation of sorts that I take my eyes off of the Display to watch my drone take off into the sky for the first couple minutes and in doing so miss any error messages that might have popped on the screen such as Compass error / Magnetic Interference errors to name a few.

This could explain how I missed the critical errors that might have saved me from a fly away right on take off.

I have tried to break this habbit but it is very difficutl as my eyes just want to watch that take off as the drone is so close.

Obviously we are more at risk than most as we fly from some really bad advantage points , so I made this video to show how dangerous it can be to miss the Flash or an error message come across the screen especially at take off.

The video shows how little Magnetic Interference it takes to put your Drone in Jeopardy of a Fly Away and how deceiving it can be to continue to fly.

When it comes to magnetic Interference , it can take many forms, Compass error / Yaw Errors / Atti Mode.
The best advice I can share is do not trust your drone to fly after you get an error no matter how fast it appears on the screen, as the damage is most likely already done.

Best to shutdown , move your take off position and start again.

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In addition to checking your DJIGo4’s map to make sure your indicated aircraft heading is accurate, you may also want to check out your take off location before turning on your aircraft:

Metal Detector iOS App:
‎Metal Detector (PRO)

Example of flying near magnetic fields:
 
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PhantomWetSuits

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In addition to checking your DJIGo4’s map to make sure your indicated aircraft heading is accurate, you may also want to check out your take off location before turning on your aircraft:

Metal Detector iOS App:
‎Metal Detector (PRO)

Example of flying near magnetic fields:

These are interesting: We use this one : You have to get very close to the objects in question and if it could isolate to just IRON , it would be great, the problem we have is that everything sets it off as metal is everywhere.

‎Tesla - Metal detector and Magnetic field recorder
 
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i had a similar issue. i discovered i was doing it to myself. i do real estate photography so i'm always in a new location. i'd get to the job and assemble my P3 on the tailgate of my truck. i always calibrated the compass due to the new location but i was standing too close to the truck. duh! now i calibrate a good distance from the truck and my magnetic interference issues have disappeared. the devil's in the details!
 

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‘Calibration’, i.e. Compensation only adjusts for on-board distortions to the ambient magnetic field. Doing so at every location is of no benefit.

My longest time since compensation is on my P2, last calibrated around Nov. 2014 when I swapped control system for Futaba. Since then I have flown as far away 1000 miles from the location with no issues.
 
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