Hi everybody, I write from Chile and I want tell you my sad story

The last weekend I went to the beach and bring my mavic air with me.
I flew the drone from apartment balcony in 4th floor, it started in OPTI mode and I moved forward 2 meters and it changed to GPS mode detecting 10 satellites and recorded point RTH, everything seemed normal, but the drone began to fly uncontrollably to my left at full speed and crashed with the building and followed flying to finally fall into the pool.
From the moment that the drone moved alone i lost the aircraft control and everything my movements were useless as shown in the video that I share you. Also you will see the high speeds that took the drone it been in normal mode flight.
Yo can see messages about magnetic field interferences, but the time was very short to make something, the fligth lasted only 51 seconds and the uncontroll only 8 seconds.
At all times I tried to land the drone but the control didn’t allow me it.

I hope you give me your advices to recovery my drone, only have my drone two months ago and now when I turn on it show me many errors and doesn’t work it.

Sorry for my english.
Thank you very much.

Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.

Thank You msinger, I will make that. The idea is that everybody see this accident, because I have seen many videos in youtube about magnetic field interferences, but they were good luck and me no.

Hi bud,

Two things.

1) Never ever a good idea to take off from a balcony, especially in South America. The reason being that MOST if not all balconies in High Seismic areas are reinforced with rebar. Another thing is that the balcony does not allow for any errors (such as what happened in this case). If you cannot find a safe open place to take off in your building, at the very least try to fly from the roof, where there might still be magnetic interference, but there is enough room above and to the sides to allow a bit of wiggle room for quick reactions.

2) If the compass was giving you a magnetic interference warning in flight, you were basically already SOL. In my case, whenever I fly I take 10 seconds to check the sensors state in the app, to make sure that the magnetic interference is in the green or at the very least in the yellow before takeoff. After takeoff, the MI usually drops to nil, but it is during takeoff and landing that most accidents related to compass errors happen.

IMHO you made 2 mistakes here, taking off from a balcony, and not checking compass. Do not feel bad though, these things happen to all of us. I hope you can fix your drone and get back in the air soon.

In the case of water damage, use a couple of silica bags and DO NOT turn on the drone. Also, take off the battery and dry it as best as you can. Water damage usually depends on the length of time the drone has been submerged, and the type of water it has been submerged in... salt water is a fast killer, fresh water will be less punishing.

No vuelvas a volar desde un balcón joder, que estás limitando demasiado tus opciones si algo sale mal. El concreto armado de los edificios en latinoamérica está lleno de acero, y eso es la muerte para la brújula del dron.

E.

I'm really sorry to hear that. I would recommend you to contact our support team to start up a case: (https://www.dji.com/support?site=brandsite&from=nav). We have the professional data analysis team who would do their best to find out the crash reason and then the corresponding resolution would be provided. You can provide your case number here in case you need further assistance.

This is pilot air--- The balcony created magnetic interference

enriquefc Posted at 2018-9-21 06:26
Hi bud,

Two things.

Thank you for your advices.

May be that to fly from balcony was bad, but with respect to checking compass, I flew 2 times before that fligth in the same area and I hadn’t problems, also i hadn’t time for that in the fatal fligth. If you see the video, only 2 seconds after to change a gps mode and record to RTH point the aircraft uncontrolled it.

I think that was a dji app error or aircraft error, for that dji must to make responsable about that.
Remember we don’t talking about a drone €100, we talking about drone €1000, I hope to have a good technology for that price. I always didn’t feel that I had aircraft control in each fligth, I never flew safe it.

I uploaded logs and I will share you.

I share you the log files of the fatal flight.

http://www.phantomhelp.com/LogViewer/S1PROVYCNDJHNKI38A6V/

Please give me your opinions.
Thank you

All i say is good luck to get your baby back to the sky. I made mistakes and the cost for repair was half price of brand new basic MA. If you have care refresh, it will save alot!

Sorry for your loss, but I strongly suspect pilot error - crazy place to fly from! I will be happy to be proven wrong when your flight log is available, but at the moment I don’t see how DJI is at fault. Yes it is $1000 worth of drone, hence you need to fly with this in mind!

I hate to say it but you just learned an expensive lesson. Hard to attribute this to anything but pilot error.

I’m sure that many of you to have a car.
Tell me, when you are driving and you make a fault, the car response at yours movements, you know???.
In the case of drone that wasn’t equal, the drone doesn’t asked me how i would hope.

paul77Air Posted at 2018-9-21 09:00
I’m sure that many of you to have a car.
Tell me, when you are driving and you make a fault, the car response at yours movements, you know???.
In the case of drone that wasn’t equal, the drone doesn’t asked me how i would hope.

Problem here is the system on your drone has a non-redundant system for positioning. The system uses info from your compass AND from the GPS. One cannot work without the other. If the compass fails, the GPS positioning will shut off and you will be kicked into ATTI mode. In ATTI mode, the drone can drift and has no way to find a position, unless the OPTI system is activated (which would've kicked in if you had been lower than on a balcony [i.e. less than 12 feet from the ground], and maybe would've protected the drone from going ballistic).

Another thing is your compass may have been fine for 1, 4, 12, 100 or 500 flights from that location, but at one point or another the MI may increase due to a number of factors, and that is the 1 flight where this accident might happen. You can try to replicate it 3000 times and never have it happen again, which is why I recommend at least checking sensors state before a flight from a new location, and at best spending 5 seconds doing that on EVERY flight, regardless of location.

When you are in a car, as per your example, with breaking specs of 20 feet to stop, you cannot expect the car to out-perform its design. If you ram the pedal racing at 120 mph and hit the breaks before the breaking distance buffer, you will crash.

As to it being a $1000 drone, yes, that is why it pays off to familiarize yourself with:
1.- The failsafe procedures (flying from a balcony would make the RTH very hard to do in case of loss of signal, etc). This was actually discussed in another post here, and the individual had the drone crash 20 floors down because the RTH placed the drone just outside of his reach beside the balcony, and the controller was non-responsive.

2.- The DJI recommended flying areas (as well as their warranty conditions).

Not to be crude, but I do not see how this would've been DJI SW or HW issues.

Hope it works out for you!

E.

enriquefc Posted at 2018-9-21 10:47
Problem here is the system on your drone has a non-redundant system for positioning. The system uses info from your compass AND from the GPS. One cannot work without the other. If the compass fails, the GPS positioning will shut off and you will be kicked into ATTI mode. In ATTI mode, the drone can drift and has no way to find a position, unless the OPTI system is activated (which would've kicked in if you had been lower than on a balcony , and maybe would've protected the drone from going ballistic).

Another thing is your compass may have been fine for 1, 4, 12, 100 or 500 flights from that location, but at one point or another the MI may increase due to a number of factors, and that is the 1 flight where this accident might happen. You can try to replicate it 3000 times and never have it happen again, which is why I recommend at least checking sensors state before a flight from a new location, and at best spending 5 seconds doing that on EVERY flight, regardless of location.

You have good points, I see you know a lot, I do not know much and maybe that inexperience played a trick on me, but I insist that DJI should do something about the interference with magnetic fields and not let the user assume all the blame before an accident for these reasons.
For example, I would have preferred a thousand times to activate the RTH when I detected these interferences, since the lack of control did not allow me to do anything to save it.

Again, I have seen several videos on the same subject in open fields and the drone has also been out of control, but after a few seconds the remote control is reconnected. In my case it was not possible because it was surrounded by buildings and a pool. Then here is where I ask myself again. Why should pilots conform and live with these errors that with high technologies could be corrected?.

Or also why dji app doesn’t warning us about these interferences before of the fligths and not during them?. If that were the case, it would be our decision to fly or not.

That day I checked UAV Forecast and Magnetology applications before to fly, then... What else do i have to check??. It will not be much?.

I leave you those questions.

Thank you.

Total reliance on these safety features and systems is the reasons accidents occur. Much like a car in your example, you can't rely on its safety features to prevent an accident.

While it is unfortunate that  the drone had lost control potentially due to these systems experiencing outside interference, the operator's choice to launch from a position where should an error occur, would lead to not being able to recover it, puts the responsibility in the owner.

DJKOR Posted at 2018-9-21 19:38
Total reliance on these safety features and systems is the reasons accidents occur. Much like a car in your example, you can't rely on its safety features to prevent an accident.

While it is unfortunate that  the drone had lost control potentially due to these systems experiencing outside interference, the operator's choice to launch from a position where should an error occur, would lead to not being able to recover it, puts the responsibility in the owner.

I agree with what you say, but I have faith that a near future the drones’s technology will be better and we won’t to have worry by those security holes anymore.
Now I will worry how to fix my drone and can follow flying and to be more careful.

As you appear not to acknowledge any personal blame for flying in a way that DJI and the comments on here recommend you don’t, I look forward to your next report with your replacement drone!

Oops, I did it again!!

paul77Air Posted at 2018-9-21 08:19
I share you the log files of the fatal flight.

http://www.phantomhelp.com/LogViewer/S1PROVYCNDJHNKI38A6V/

I am very sorry for your crash. But you had serious error messages from the outset and never a stable satellite link. Despite of this it was your choice to go for this flight. As others have stated, this was not a good take off location and it would have been wise to go somewhere else. Take it as a painful lesson learned.

paul77Air Posted at 2018-9-21 16:46
You have good points, I see you know a lot, I do not know much and maybe that inexperience played a trick on me, but I insist that DJI should do something about the interference with magnetic fields and not let the user assume all the blame before an accident for these reasons.
For example, I would have preferred a thousand times to activate the RTH when I detected these interferences, since the lack of control did not allow me to do anything to save it.

With respect, magnetic fields are a fact of nature and not within the control of DJI.
The compass relies upon the Earth's magnetic field to detect north.

Material containing iron (ferrous materials) or magnets can bend and distort the Earth's magnetic field. Such items are commonly iron rebar in concrete structures, vehicles and structural components of a building.

When you take off from a location close to such ferrous (or magnetic) materials the compass does not know that it is being deflected (fooled), but when your drone has some altitude and the compass now swings to point to the Earth's magnetic north the IMU detects no change in the yaw axis so they have an argument because the electronics are confused.

So the IMU now ignores the GPS signals and therefore positioning information so your drone is now at the mercy of the wind.

I tried to simplify this but I hope that you get the general idea.

I really am a boffin

paul77Air Posted at 2018-9-21 08:19
I share you the log files of the fatal flight.

http://www.phantomhelp.com/LogViewer/S1PROVYCNDJHNKI38A6V/

Hi paul,

Your 51 second flight is not in this flightrecord, i see a flight of  4m 53 secs.

cheers
JJB

Thank you very much for your advices and comments, I have learned much and I know that we can encounter with these interferences of magnetic fields during fligths.
I have read that the magnetics fields are not necessarily where there is metal or iron.

JJBspark, my fligth only is of 51 seconds, the link is:

http://www.phantomhelp.com/LogViewer/S1PROVYCNDJHNKI38A6V/

paul77Air Posted at 2018-9-22 04:12
Thank you very much for your advices and comments, I have learned much and I know that we can encounter with these interferences of magnetic fields during fligths.
I have read that the magnetics fields are not necessarily where there is metal or iron.

Hi Paul,

Thank you, i do see your 51 seconds flight.
Has been said, magnetic inteference. Normally the flightmode changes into ATTI in the log, your mode goes from OPTI to P-GPS, but as it was hard to control must have been in ATTI.

cheers
JJB

paul77Air Posted at 2018-9-21 16:46
You have good points, I see you know a lot, I do not know much and maybe that inexperience played a trick on me, but I insist that DJI should do something about the interference with magnetic fields and not let the user assume all the blame before an accident for these reasons.
For example, I would have preferred a thousand times to activate the RTH when I detected these interferences, since the lack of control did not allow me to do anything to save it.

Hi bud,

I really do not know that much, but I did read up and test all my drones (Spark, MA, MPP) and, particularly, their failsafe and safety systems, for quite a bit before I really started putting them through their paces and flying a little more boldly.

As to the RTH, there is a real problem with activating it while you are less than a certain distance from the HP (20 meters, I think), the aircraft will just land.

As to the warnings before the flight, maybe there were none to report. Maybe your compass was fine while taking off from the balcony and as soon as you took the bird out a few feet, the compass received a wave of MI that made it deactivate.

UAV Forecast checks for "planetary" magnetic interference. This means usually solar activity can affect the Earth's Magnetic Field. When the KP index is high, you can expect more interference in the general area. However, it cannot, of course, account for you flying right next to a cell tower, a huge magnet, or in your case, a reinforced building. You are right to check UAV Forecast, but to be honest I really use it more to know the wind gusts conditions at the particular altitude I am wanting to fly in.

In any case, I am no one to be teaching lessons. I do hope you can get your drone repaired and I would be willing to bet that you will have gained valuable experience from this accident.

Good luck getting back airborne, and I do hope DJI helps you out with fixing your bird.

E.

enriquefc Posted at 2018-9-21 06:26
Hi bud,

Two things.

1) Never ever a good idea to take off from a balcony, especially in South America. The reason being that MOST if not all balconies in High Seismic areas are reinforced with rebar.

I would say that is true for any concrete balcony anywhere in world.  Regardless of Seismic risk.  When concrete is used to support loads (like a raised floor or balcony), Rebar, steel beams, or metal mesh is a requirement.  Being, concrete is strong under compression, while weak under tension.  Where as steel is strong under tension.

paul77Air Posted at 2018-9-21 16:46
You have good points, I see you know a lot, I do not know much and maybe that inexperience played a trick on me, but I insist that DJI should do something about the interference with magnetic fields and not let the user assume all the blame before an accident for these reasons.
For example, I would have preferred a thousand times to activate the RTH when I detected these interferences, since the lack of control did not allow me to do anything to save it.

but I insist that DJI should do something about the interference with magnetic fields

There is nothing DJI can do about sources of Magnetic intereference to Earth's Magnetic Field.  

Only thing DJI could do is work on utilizing IMU data** coupled to GPS data to aid in flying when there is severe compass interference or compass fails.  In your case, drone did not have GPS information upon takeoff.  As such, even mentioned possibility would not have helped.


**IMU data should be providing inertial movement Along and Around all three axis (X,Y,Z).
Surge (forward/backwards) movement along X-axis and Roll (tilt side to side) around X-axis.
Sway (left/right) movement along Y-axis and Pitch (nose up/down) around Y-axis.
Heave (up/down) movement along Z-axis and Yaw (heading) around Z-axis.



Part of issue in this is conventions that are tied to compass points.  NED convention:

Movement along X-axis equates with North / South, with +X being North.
Movement along Y-axis equates with East / West, with +Y being East.
Movement along Z-axis equates with Descent / Ascent, with +Z being Descent.



''CH Robotics' sensors use a common aeronautical inertial frame where the  x-axis points north, the y-axis points east, and the z-axis points down  as shown below.  We will call this a North-East-Down (NED) reference  frame.  Note that because the z-axis points down, altitude above ground  is actually a negative quantity.''

but I insist that DJI should do something about the interference with magnetic fields

Questions:
1) Did you get any Compass Warning or Error message on GO-4 App running on your SmartDevice prior to taking off?
2) Was GO-4 App showing ''Green'' Good to fly or possibly ''Red''?
3) Have you previously gotten any warnings about Compass needing to be calibrated?

JERRY K Posted at 2018-9-21 07:17
This is pilot air--- The balcony created magnetic interference

That is my first thought.  when it switched to GPS its compass was missed up

Don’t take off from concrete! It has metal inside!
And also I wouldn’t take off from a balcony, maybe from a roof and ONLY hand launch away from concrete ground!

Fly safe all
Alex

Thank You for your explanations and help.
I can tell you that in fatal fligth didn’t show me messages about calibration, in my previously fligths in the same place (but in the grass on the 1st floor) yes I had to calibrate 2 times the compass, because the app needed it.

Alex B. Posted at 2018-9-22 15:06
Don’t take off from concrete! It has metal inside!
And also I wouldn’t take off from a balcony, maybe from a roof and ONLY hand launch away from concrete ground!

Although good advice, sometimes not taking off from concrete isn't possible. Typically if you do, you will need to do a compass calibration. If the metal is causing too much interference, it will just fail. I've taken off on concrete quite a few times and even off a building rooftop with nearby plant and cell towers and after a couple of calibrations, have had no dramas. Obviously these are cases though where, 1) I have full GPS lock and 2) I have open space to give room for error. I'd never take off without satifying those two requirements.

DJKOR Posted at 2018-9-23 02:14
Although good advice, sometimes not taking off from concrete isn't possible. Typically if you do, you will need to do a compass calibration. If the metal is causing too much interference, it will just fail. I've taken off on concrete quite a few times and even off a building rooftop with nearby plant and cell towers and after a couple of calibrations, have had no dramas. Obviously these are cases though where, 1) I have full GPS lock and 2) I have open space to give room for error. I'd never take off without satifying those two requirements.

BIG mistake! Calibrate in an environment that is subject to magnetic interference, then take off and fly away from the same interference? Chances are that the compass will realign whilst airborne and end up not knowing where north is

InvisibleName 7 Posted at 2018-9-23 03:43
BIG mistake! Calibrate in an environment that is subject to magnetic interference, then take off and fly away from the same interference? Chances are that the compass will realign whilst airborne and end up not knowing where north is

That is a very good point. I thought of it in the sense of the compass internally knowing which way is magnetic north and you are calibrating it to read the "noise" in the area so it can compensate.

In either case, the calibration occurs off the ground surface which should eliminate the reinforcement in the concrete causing issues, but as for external electromagnetic interference, well that's definitely something to think about.

DJKOR Posted at 2018-9-23 03:56
That is a very good point. I thought of it in the sense of the compass internally knowing which way is magnetic north and you are calibrating it to read the "noise" in the area so it can compensate.

In either case, the calibration occurs off the ground surface which should eliminate the reinforcement in the concrete causing issues, but as for external electromagnetic interference, well that's definitely something to think about.

How about just taking off from your hand as I always do with my spark,
That way you have your drone away from concrete and metal and you get 0 compass interference,
It’s all green, I was checking it

Fly safely
Alex

paul77Air Posted at 2018-9-22 16:06
Thank You for your explanations and help.
I can tell you that in fatal fligth didn’t show me messages about calibration, in my previously fligths in the same place (but in the grass on the 1st floor) yes I had to calibrate 2 times the compass, because the app needed 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 compass values in your app also check small red triangle in the lower left corner of your telemetry, it should be on the same heading as your aircraft.

paul77Air Posted at 2018-9-22 16:06
Thank You for your explanations and help.
I can tell you that in fatal fligth didn’t show me messages about calibration, in my previously fligths in the same place (but in the grass on the 1st floor) yes I had to calibrate 2 times the compass, because the app needed it.

Avoid Compass Crash.

Tip To Help Avoid compass interference and crash.
1/ Never calibrate Compass unless prompted to.

2/ start AC leave until you receive enough gps lock ,
You can also check compass values in your app.

3/ if you get Compass interference turn off AC and move to another location,
without interference.

4/ In bottom left hand corner on your map you will see small red triangle, check to make sure that this triangle is pointing in the same direction (heading) as your AC, this will show good compass on the ground.



Raise AC to height of 8ft
Hover for 20 seconds
Fly forward 2ft
Backward 2ft
Left 2ft
Right 2ft
Up 2ft
Down 2ft
Yaw left
Yaw right
Each time returning to hover position
If you have a good horizontal each time, you will then know you have good gps good IMU and good Compass, and your ready to fly.

This exercise takes less than 2 minutes and is worthwhile doing before every flight,

hallmark007 Posted at 2018-9-23 15:55
Avoid Compass Crash.

Tip To Help Avoid compass interference and crash.

Thank You for tips, i hope put them in practice when I have my Mavic in the air again

Same thing happened to me last Friday on a construction project I’m involved in. 20mph left at 20ft two counterclockwise 360’s then CRASH! Very grateful nobody was hurt! Would love to know WT*!!!

Hi everybody.

Someone know how much time take dji in give us a response about one case?.

I’m still waiting a response about my case almost one month.

Thank You.

enriquefc Posted at 2018-9-21 06:26
Hi bud,

Two things.

You can say all you want about flying these drones inappropriately and this is evading the point. That fact is these drones are flying by themselves. This is the issue. dji has software issues with these drones. Number one,there is no safety shutdown built into these drones. And number two they are dangerous and someone is gonna get killed. dji is taking no responsibility in these issues. Everything is normal. No it’s not normal and is dangerous.

enriquefc Posted at 2018-9-21 06:26
Hi bud,

Two things.

You can say all you want about flying these drones inappropriately and this is evading the point. That fact is these drones are flying by themselves. This is the issue. dji has software issues with these drones. Number one,there is no safety shutdown built into these drones. And number two they are dangerous and someone is gonna get killed. dji is taking no responsibility in these issues. Everything is normal. No it’s not normal and is dangerous.