Lost Mavic after loss of connection

[sar104]

Was there metal in the car park? Compass may have been compromised.

There were no compass problems on this flight.

 

[choo choo]

What I really do not understand in the whole story, if the signal is lost (I have tried it many times) the aircraft should return to the place where it take off in first place. So it is in setup by me: return to home if the signal is lost -> rth is 90 m (200 ft cca) -> before flight allways set current home position, and more important if I am 50 km away from last calibration of my compas position, allways calibrate compas on current position, after that I go fly! This four things prevent that situation which happened to you, that the drone just flyaway! Sorry about that, but I do not think this would have happened that this was all set...my prediction. Many things can affect the signal quality, it is not necessary that it is always the distance. Unless your dron was hacked by somebody else...

This isn’t just a signal loss, or the Mavic would RTH this is a sudden total power loss, as if the battery was there one minute, gone the next.

 

[Zmaj1701]

This isn’t just a signal loss, or the Mavic would RTH this is a sudden total power loss, as if the battery was there one minute, gone the next.

Ok, if it was total power loss, that is another problem that could affect all of us. DJI would really have to say something about this problem, in the mean time need to find that Drone!

I still do not understand things here, if a total loss of power has occurred where is the Drone??? It was on line of sight? Where is it? Total power loss will couse that Drone gonna fall from the sky like a rock!

 

[JDawg]

Ok, if it was total power loss, that is another problem that could affect all of us. DJI would really have to say something about this problem, in the mean time need to find that Drone!

I still do not understand things here, if a total loss of power has occurred where is the Drone??? It was on line of sight? Where is it? Total power loss will couse that Drone gonna fall from the sky like a rock!

Sar104 posted the path to follow on Page 1 to find the drone. Problem is a by passer who sees it would need to cooperate...

 

[Zmaj1701]

There were no compass problems on this flight.

If the commpas is calibrated 150 km from new takeoff site, that can couse the problem for the drone to back on HP! But, From experience I can say that not even 300 kn per line North/South is no problem but on the East/West route is a big problem.

 

[Kmac187]

15% discount ! that’s the best they will do , data or no data , drone or pilot error. It doesn’t matter

 

[JDawg]

15% discount ! that’s the best they will do , data or no data , drone or pilot error. It doesn’t matter

Many have had their drones replaced but you must have it to send back which seems reasonable.

 

[BJR981S]

Actually I'm not sure that you really understand the sensor technology in these aircraft at all. In the many logs that I've looked at related to compass issues, lack of calibration has possibly arisen once as a cause. And many users have been flying the Phantom and Mavic aircraft for years without recalibration, and the log data do not indicate any problems. If you had ever looked at these data yourself you would know that.

And so, while regular calibration should not cause any problems itself, it certainly isn't necessary, which is why, presumably, DJI guidance for many of their models has been to calibrate only when the FC requests it. That fact, alone, should tell you that arguing that DJI knows best, even though they have never explained their intermittent "recalibrate if you move location" or "recalibrate regularly" strategy, is not logical.

"The alert that is generated by the app and does so when excessive compass interference is detected. It neither alerts for low level magnetic anomalies introduced by the drone itself. Or for significant magnetic anomalies in the area of flight that you may encounter."​

What on earth is that statement supposed to mean? So it detects magnetic interference, but not interference due to the drone and not interference where you are flying? What, exactly, does that leave for it to detect?

And then the old nonsense again about calibration correcting for deviation or local magnetic anomalies. It's completely, trivially obvious that it cannot do that. True north is an arbitrary direction - it cannot measure or detect true north. Deviation is computed based on a global magnetic model, not measured. Even a cursory literature search would confirm that.

I'm afraid that once again it is you propagating disinformation, not @Meta4.

Thanks for your comments. The comments below are not strictly directed at you but to all those that are so sure they are correct without providing any real logic or reference material. The "you are all wrong the manufactures are wrong the world is wrong but I am right". Gang. Some of the comments are directed at your statements as I felt they need to be clarified. I don't like the reference you made that I am propagating misinformation when all I do is state fact based references. And that Meta4 is OK when all he does is post that anyone that disagrees with him is stupid. And provides no references only opinion.

I keep telling myself that I will ignore all the calibration misinformation but I think of all the members that are being confused. And really ....really. Will somebody post some reference based facts not allude to "Literature" or at least state some of their logic.

"Deviation is computed based on a global magnetic model, not measured. Even a cursory literature search would confirm that." please provide link to literature. This is completely at best guess. And one based on poor implementation logic.

Firstly I should have said declination to be more precise. But its still valid as described in the Wiki link below. Deviation and Declination can be used interchangeably.

Magnetic deviation - Wikipedia

Here is my reference link. Showing that the declination is calculated based on the current local coordinates.

Magnetic Declination in Sydney, Australia input your own city and you will see the angle needed to adjust for your location.

So it detects magnetic interference, but not interference due to the drone and not interference where you are flying? What, exactly, does that leave for it to detect? You argue my point for me.? But don't understand the Logic.

If you read the Wiki reference you will see that compass in ships are calibrated by placing magnets near the compass binnacle. This is how it was done in the good old days to counteract local magnetic anomalies due to the steel construction of the ship.

It is "calibrating" its 360 degree reference. By compensating for the anomalies.

In the drone, if the calibration is is done without any additional surrounding magnetic anomalies. (e.g. Away from your car or steel structure, radio steel tower etc) it will set its reference calibration based on the magnetic anomalies of the drone itself. Including the magnets in the motors. This is one of the reasons it asks you to calibrate the compass away from all localised magnetic anomalies. So it detects magnetic interference, but not interference due to the drone. Like the ship compass calibration it is compensating for any anomolies. Have no idea what you meant by this statement in your reply but I hope this helps.

This reference will degrade over time as the magnetic fields of iron based components get magnetised by the Spinning motors and the magnetic fields that are magnetising components in the drone.

So the reference needs to be recalibrated over time.

and not interference where you are flying? when you don't do the calibration where the magnetic interface is located? It obviously can't calibrate for that. Like I said you argue my point for me. How can it accurately determine what is required. Remember when you calibrate the compass its using the Accelerometers (in 2 axis) to determine the speed of rotation and how to "tick off" each compass degree. And it's a bit hard for the drone to point strait down and spin in flight for the second compass calibration axis to do it by itself.

What, exactly, does that leave for it to detect?

What it is meant to detect is the surrounding magnetic field based on its reference map so it can determine in all directions an accurate aircraft / compass movement in degrees.

True north is an arbitrary direction

It's vary far from arbitrary. The fact is that all cartography is based on True North, not Magnetic north. Including the GPS grid makes it not arbitrary. Any GPS based co-ordinate piloting must be done on a True North heading.

- it cannot measure or detect true north. Again you have some misconceptions that need correction. The magnetic compass indeed cannot detect True North. The compass detects Magnetic North. Magnetic North to True North can be calculated based on your present Latitude and Longitude. ( read the magnetic declination reference above) So when you do your Compass calibration by reading your GPS coordinates it knows the correction degrees to True North so it can calibrate to it in the compass reference. Pity the poor souls that ignore the manual and calibrate the compass indoors. Not a biggy just RTH could dive off in the wrong direction.

These are points that are demonstrated by "Real Pilots" calibrating their compasses multiple times during a flight. To allow for the magnetic declination drift assisted with changing locations. Some drone manufacturers recommend that you calibrate your compass if you travel more that about 300Klm from your domicile location. I wonder why they would say that.....

The biggest question of all is why do I continue to comment on these compass posts. I should know better than to waste my time commenting to those that will not accept anything other that the comments of people that agree with them.

I believe psychologists call this "Confirmation bias"

And yes I do understand sensors only too well as a Hardware System designer and Programmer for many years I do have experience in both the hardware and how people implement function based on that HW. Yes, many people have flown for years without doing constant calibrations of their compass. And those that don't travel will likley never have an issue unless they are really unlucky. The owners that have travelled to another hemisphere and complained that their drone flew further out to sea when a RTH was commanded. Well I have no sympathy.

Compass calibration errors will only account for a statistically small amount of problems on their own. But when that is coupled with Pilots that do not know how to fly and rely on the automation too much, they will be more likely to be impacted.



Cheers

 

[BARRAVi DRONE]

Hello. I’m Fer Barravi from Mexico. I just had the same problem. I lost My Mavic Pro at the sea, at Cabo San Lucas, Baja California Sur, Mexico. I was flying in good conditions, always in sight to the drone. What i think is causing the remote linking loose is the KP solar factor. I saw My Mavic falling like a rock after the signal with the RC was lost. No birds, no crash, no distanance or hight theory. It was an unexpected signal interruption. Sorry for your lost. Another thing made me sad was that I didnt find the drone, and for sure the batrery will polute the ocean and this place where I was flying is a natural preserved zone Where lionseas, whales and other fauna lives. I didn’t find infromation for this problem. I hope this batteries are not too danger for the environment.

 

[JDawg]

What i think is causing the remote linking loose is the KP solar factor. I saw My Mavic falling like a rock after the signal with the RC was lost. .

Nope

Please Post Your Flight Log

 

[BARRAVi DRONE]

Please Post Your Flight Log

For what for? Simply, we are loosing drones because solar factor.

 

[JDawg]

For what for? Simply, we are loosing drones because solar factor.

No. If you want to know the truth post your logs. The 'solar factor' is as likely as martians.

 

[Sportking]

From reading various threads regarding such topics as "flying over water" and "lost drones" it is evident that a certain amount of risk will always be present when flying our drones. Though very comprehensive and sophisticated, the DJi hardware/software/firmware components are no different to the rest of the tech industry in that they will never be 100% reliable.

The best we can do is to regularly calibrate the compass and sensors and, as previously mentioned, take a careful inventory of the geographical environment and weather conditions prior to launch. Also, ensure that the "Return to Home on Lost Signal" setting is always activated.

If for whatever reasons erratic flight behaviour has previously occurred when flying over water, it's probably a good idea to deactivate the downward facing sensors at least to determine if this resolves the issue.

Is it possible, since takeoff was from a car park, that steel-reinforced concrete could have caused a faulty compass/home point recording which could cause the drone to fly toward the incorrect home point when signal was lost?

 

[SpinItUp]

Picking that CP was maybe not the smartest decision, to just fly over many premises pumping out signals in every direction.
I think the land nearer to the edge and away from the direction of flight would've avoided the signal loss.
Or better still a vantage point higher, of which I can see many just a skip and a jump away.

 

[jwadsworthza]

1. DJI will blame this on pilot error.
2. MP2 or MP, I have had an issue with the RC loosing connection while watching the drone from no less than 20 meters. RTH actually worked, but most definitely not to the settings i had set. The drone flew straight to the location and landed. If there would have been any obstruction the drone would have hit it. RTH in that instance may or may not have worked.
3. If you have line of sight and at 600 feet you lose connection then it is possibly a dud firmware update.

I have one thing to say about DJI support. They will not take accountability, they will blame the pilots. They are not interested in incurring costs by replacing defective drones. I would like to see stats of actual warranty repairs over and above placing the blame on us. As for the missing drone, the evidence is gone, even proof of RC failure will not get them to admit they have quality issues.

Here's hoping we get a decent drone manufacturer to fill the bad quality void so we kick DJIs arse back into the void

DJI is just a third rate drone manufacturer with market share. Like Nokia of old, who got kicked in the arse and where are they now... DJIs turn is coming, not if but when!

GOODBYE DJI

 

[Dave A]

I have had an issue with the RC loosing connection while watching the drone from no less than 20 meters. RTH actually worked, but most definitely not to the settings i had set. The drone flew straight to the location and landed. If there would have been any obstruction the drone would have hit it.

In that scenario RTH worked as it should.

 

[BudWalker]

........
- it cannot measure or detect true north. Again you have some misconceptions that need correction. The magnetic compass indeed cannot detect True North. The compass detects Magnetic North. Magnetic North to True North can be calculated based on your present Latitude and Longitude. ( read the magnetic declination reference above) So when you do your Compass calibration by reading your GPS coordinates it knows the correction degrees to True North so it can calibrate to it in the compass reference. .......

This isn't correct and it's already been explained to you here
Mavic 2 Pro Flyaway

In summary, determining declination is not done during the compass calibration. Rather, declination is determined for each flight. That's why the AC can be moved large distances without requiring a calibration.

 

[BudWalker]

........
These are points that are demonstrated by "Real Pilots" calibrating their compasses multiple times during a flight. To allow for the magnetic declination drift assisted with changing locations. Some drone manufacturers recommend that you calibrate your compass if you travel more that about 300Klm from your domicile location. I wonder why they would say that.....
.....

This also isn't correct. "Real Pilots" don't calibrate the compass during flight. They may set a new declination offset if required. But, this isn't anything like a compass calibration.

 

[sar104]

Thanks for your comments. The comments below are not strictly directed at you but to all those that are so sure they are correct without providing any real logic or reference material. The "you are all wrong the manufactures are wrong the world is wrong but I am right". Gang. Some of the comments are directed at your statements as I felt they need to be clarified. I don't like the reference you made that I am propagating misinformation when all I do is state fact based references. And that Meta4 is OK when all he does is post that anyone that disagrees with him is stupid. And provides no references only opinion.

I keep telling myself that I will ignore all the calibration misinformation but I think of all the members that are being confused. And really ....really. Will somebody post some reference based facts not allude to "Literature" or at least state some of their logic.

"Deviation is computed based on a global magnetic model, not measured. Even a cursory literature search would confirm that." please provide link to literature. This is completely at best guess. And one based on poor implementation logic.

Firstly I should have said declination to be more precise. But its still valid as described in the Wiki link below. Deviation and Declination can be used interchangeably.

Magnetic deviation - Wikipedia

Here is my reference link. Showing that the declination is calculated based on the current local coordinates.

Magnetic Declination in Sydney, Australia input your own city and you will see the angle needed to adjust for your location.

Well thanks for taking the time to write all that. I'll make one last attempt to address it point by point, and if that doesn't work then I'm going to have to abandon this discussion.

Deviation and declination are the same thing - no problem with you using deviation. But I'm confused - you asked for a link to literature showing that declination is computed by a global model, and then you provided the link yourself. Declination is not measured - it is calculated.

So it detects magnetic interference, but not interference due to the drone and not interference where you are flying? What, exactly, does that leave for it to detect?

You argue my point for me.? But don't understand the Logic.

If you read the Wiki reference you will see that compass in ships are calibrated by placing magnets near the compass binnacle. This is how it was done in the good old days to counteract local magnetic anomalies due to the steel construction of the ship.

It is "calibrating" its 360 degree reference. By compensating for the anomalies.

Yes - that's fascinating history, but is not how 3-axis magnetometers work. The magnetic field strength is measured on the three orthogonal principle axes of the aircraft (x- forwards, y- right, z- down). That field is assumed to be the linear sum of the earth's field and the magnetic field due to the aircraft itself. Those fields can be distinguished by rotating the aircraft (the calibration procedure) since, as measured by the magnetometers, the earth's field appears to rotate while the aircraft's field doesn't. That allows the FC to calculate the magnetic field components due to the aircraft's magnetic field, store them as the calibration, and then subsequently subtract them from the total measured field in flight - leaving just the components of the earth's magnetic field.

That now allows the FC to use the magnetometer data to determine the direction of magnetic north relative to the drone. Magnetic north, not true north.

In the drone, if the calibration is is done without any additional surrounding magnetic anomalies. (e.g. Away from your car or steel structure, radio steel tower etc) it will set its reference calibration based on the magnetic anomalies of the drone itself. Including the magnets in the motors. This is one of the reasons it asks you to calibrate the compass away from all localised magnetic anomalies.

Yes - that is saying the same thing - it is subtracting the magnetic field of the drone itself.

So it detects magnetic interference, but not interference due to the drone. Like the ship compass calibration it is compensating for any anomolies.

Have no idea what you meant by this statement in your reply but I hope this helps.

This reference will degrade over time as the magnetic fields of iron based components get magnetised by the Spinning motors and the magnetic fields that are magnetising components in the drone.

So the reference needs to be recalibrated over time.

Your original statement was:

"The alert that is generated by the app and does so when excessive compass interference is detected. It neither alerts for low level magnetic anomalies introduced by the drone itself. Or for significant magnetic anomalies in the area of flight that you may encounter."​

My point was that there are only two kinds of magnetic interference - the magnetic field of the drone itself or anomalous external magnetic fields at the flight location. You just stated that it doesn't detect either of those, which doesn't leave any kind of interference for it to detect.

It's certainly possible that the magnetic state of the aircraft might change over time, although the alternating field produced by the motor currents is unlikely to be the cause since alternating fields don't induce ferromagnetism and are actually the primary method for demagnetizing ferromagnetic materials.

and not interference where you are flying?

when you don't do the calibration where the magnetic interface is located? It obviously can't calibrate for that. Like I said you argue my point for me. How can it accurately determine what is required. Remember when you calibrate the compass its using the Accelerometers (in 2 axis) to determine the speed of rotation and how to "tick off" each compass degree. And it's a bit hard for the drone to point strait down and spin in flight for the second compass calibration axis to do it by itself.

What, exactly, does that leave for it to detect?

What it is meant to detect is the surrounding magnetic field based on its reference map so it can determine in all directions an accurate aircraft / compass movement in degrees.

I don't even remotely understand what you are trying to say there, so I can't comment on whether I'm arguing your point or not.

True north is an arbitrary direction

It's vary far from arbitrary. The fact is that all cartography is based on True North, not Magnetic north. Including the GPS grid makes it not arbitrary. Any GPS based co-ordinate piloting must be done on a True North heading.

It's possible that you don't understand the definition of the term "arbitrary". It means that the location of the true north pole is independent of any measurable parameter - it has arbitrarily been defined to be where it is to form the basis of the lat/long coordinate system. Our cartographic system is entirely arbitrary. True north is loosely associated with the rotational axis of the earth, but that wobbles around too. As a result of it being arbitrary, there is nothing that any sensor on the drone can measure to determine the direction of true north - it can only determine magnetic north by reference to the earth's magnetic field.

- it cannot measure or detect true north.

Again you have some misconceptions that need correction. The magnetic compass indeed cannot detect True North. The compass detects Magnetic North. Magnetic North to True North can be calculated based on your present Latitude and Longitude. ( read the magnetic declination reference above) So when you do your Compass calibration by reading your GPS coordinates it knows the correction degrees to True North so it can calibrate to it in the compass reference. Pity the poor souls that ignore the manual and calibrate the compass indoors. Not a biggy just RTH could dive off in the wrong direction.

Exactly. The compass is used to determine magnetic north. True north is offset from that by the location-dependent declination value. And the declination is calculated (not measured) based on your location from the global magnetic model in the firmware. You are now saying exactly what I said that you claim to disagree with.

These are points that are demonstrated by "Real Pilots" calibrating their compasses multiple times during a flight. To allow for the magnetic declination drift assisted with changing locations. Some drone manufacturers recommend that you calibrate your compass if you travel more that about 300Klm from your domicile location. I wonder why they would say that.....

Now you are back to old-fashioned analog compasses that need to be adjusted to correct for declination. The 3-axis magnetometers in these drones do not need that - the adjustment is made automatically from the global model (you can see it happen in the DAT log event stream as soon as the aircraft achieves a GPS lock and determines its location.

The biggest question of all is why do I continue to comment on these compass posts. I should know better than to waste my time commenting to those that will not accept anything other that the comments of people that agree with them.

I believe psychologists call this "Confirmation bias"

I think that you continue commenting because you don't understand how these sensors work - probably because you have not kept up with the technology. Confirmation bias is not the problem here - no one who you are arguing with is basing their understanding of these systems on what others are asserting.

And yes I do understand sensors only too well as a Hardware System designer and Programmer for many years I do have experience in both the hardware and how people implement function based on that HW. Yes, many people have flown for years without doing constant calibrations of their compass. And those that don't travel will likley never have an issue unless they are really unlucky. The owners that have travelled to another hemisphere and complained that their drone flew further out to sea when a RTH was commanded. Well I have no sympathy.

Well no - the problem seems to be that you don't understand anything more recent than analog compasses. And, as I mentioned, there are no cases that I'm aware of where a change in declination due to a change in location has caused any problems at all, let alone uncontrolled flight or a fly away. Perhaps you could point to an example of such a case if you know of any.

Compass calibration errors will only account for a statistically small amount of problems on their own. But when that is coupled with Pilots that do not know how to fly and rely on the automation too much, they will be more likely to be impacted.

Cheers

As I said - I haven't seen compass calibration issues cause problems at all, independent of whether the pilots understand what they are doing, or rely on the automated systems.

 

[sar104]

For what for? Simply, we are loosing drones because solar factor.

No - that's definitely not why you lost your drone. You can post your flight log if you want the event explained, or you can continue to blame it on a non-existent fantasy explanation if that makes you feel better. Your choice entirely.