First flight crash

[Enrico BBB]

This is the video of the flight. You can see as following:

- 13 second on the video, 0s on the flight log TAKE OFF
- ... climbing and sligh rotation up to 1,08s on the video, 55" on the log.
- 1,08 on the video, 55" on the log drone starts to go on the right but it was not my input.... it unexpected starts this movement without any imput. As you see speed was fast raising even if the drone was set on C mode (in order to avoid bad surprises).
- 1,13 on the video, 60" on the log CRASH. All the data after this point are completely wrong as you can see.....

i don't know... please tell me your opinion... i really can't understand what's happened.

Thank you so much

https://wetransfer.com/downloads/2c4d67e4fb3e8b52dd1aaed80e4b3c8820191211073146/5477d0b12119ee025cbaa8c50643d7fa20191211073146/015d99

 

[Meta4]

i think this is the file we need.... isn't it? thank you all for your precious help.

Looking at your data, the incident is not an obvious Yaw Error situation caused by steel or iron being very close to the compass sensor at the start of the flight.

At 0:55.3 something unusual is happening with the drone starting to roll toward one side despite no joystick imput.
At first the roll is slight but by 0:57.1, the roll is 20 degrees.
The drone is moving and accelerating with no joystick input and at 0:59.6 the collision happens.
data after that is messed up because of the impact on the sensors.
The drone spins around, pitches steeply and rolls almost upside down.
The speed increases sharply, the drone rolls back in the other direction, again almost upside down, all the while losing height.
By 1:01.7, it is losing GPS, probably due to rolling.

Perhaps @sar104 can read a little more into the data.

 

[Enrico BBB]

Looking at your data, the incident is not an obvious Yaw Error situation caused by steel or iron being very close to the compass sensor at the start of the flight.

At 0:55.3 something unusual is happening with the drone starting to roll toward one side despite no joystick imput.
At first the roll is slight but by 0:57.1, the roll is 20 degrees.
The drone is moving and accelerating with no joystick input and at 0:59.6 the collision happens.
data after that is messed up because of the impact on the sensors.
The drone spins around, pitches steeply and rolls almost upside down.
The speed increases sharply, the drone rolls back in the other direction, again almost upside down, all the while losing height.
By 1:01.7, it is losing GPS, probably due to rolling.

Perhaps @sar104 can read a little more into the data.

Thank you so much for your answer.
I'd like to know if, in your opinion, that could be my fault somewhow...
Thank you

 

[slup]

May I ask if you perhaps calibrated the compass before the flight ?

The reason for me asking is that I can't get the drone heading to match when I look at the flight in your attached clip vs. when looking at it through the flight log in Airdata (see my pic. below) ... In the video you crash to the right but according to the log you crash to the left. Seems that the compass is 180 degree wrong.

If you calibrated the compass in a high magnetic area then you merged in that interference & once high enough out from the interference the compass & the IMU differed so much that the drone completely lost it's knowledge about the heading ... usually when this happens the drone goes into the famous "toilet bowl" spiral and goes out of control.

Can also see that you launched with rather few locked satellites ... I usually wait until I at least have a minimum of 10-12 so I don't risk Atti-mode if I loose one ... don't think this was the problem this time though as Atti-mode kicks in after the crash.

 

[Enrico BBB]

May I ask if you perhaps calibrated the compass before the flight ?

The reason for me asking is that I can't get the drone heading to match when I look at the flight in your attached clip vs. when looking at it through the flight log in Airdata (see my pic. below) ... In the video you crash to the right but according to the log you crash to the left. Seems that the compass is 180 degree wrong.

If you calibrated the compass in a high magnetic area then you merged in that interference & once high enough out from the interference the compass & the IMU differed so much that the drone completely lost it's knowledge about the heading ... usually when this happens the drone goes into the famous "toilet bowl" spiral and goes out of control.

Can also see that you launched with rather few locked satellites ... I usually wait until I at least have a minimum of 10-12 so I don't risk Atti-mode if I loose one ... don't think this was the problem this time though as Atti-mode kicks in after the crash.

View attachment 87875

I didn't activate the ATTI. It activated it by itself.
I make the procedure befor flight on that red rubber surface but, taken I was at the first flight with this drone maybe I made some mistakes .. I really don't know
I think even if a problem with compass calibration could have occurred the controller has not to get completely out of control. I try to activate come home function, nothing happened.... How could the drone by itself get out of control and flying like crazy that way?

 

[slup]

I didn't activate the ATTI. It activated it by itself.
I make the procedure befor flight on that red rubber surface but, taken I was at the first flight with this drone maybe I made some mistakes .. I really don't know
I think even if a problem with compass calibration could have occurred the controller has not to get completely out of control. I try to activate come home function, nothing happened.... How could the drone by itself get out of control and flying like crazy that way?

Yeah ... I know you didn't activated atti mode by your self ... because you can't, the mini haven't that possibility to do it manually. But if it looses to many satellites it will by itself go to atti.

But back to my question ... did you or did you not calibrate the compass in the launch location before you took off ?

 

[Enrico BBB]

I

Yeah ... I know you didn't activated atti mode by your self ... because you can't, the mini haven't that possibility to do it manually. But if it looses to many satellites it will by itself go to atti.

But back to my question ... did you or did you not calibrate the compass in the launch location before you took off ?

No! I followed some instruction about positioning of the done before take off but I don't remember to have done the compass calibration.

 

[slup]

I
No! I followed some instruction about positioning of the done before take off but I don't remember to have done the compass calibration.

I can only interpret what I see ... according to your video the drone crashes to the right but according to the flight log it crashes with the left side of the drone first (look at the drone triangle in my earlier attached pic). For me that indicates a 180 degree compass error. You launched in a place surrounded by a high steel fence ... & under that rubber on the ground it perhaps was a steel plate or reinforcements, all highly magnetic.

How to get an compass error ...

Perhaps you stored the drone close to an magnetic object & by that magnetized it ... or you tried to launch in a magnetic interfered area, steel reinforcement or electrical installation close under ground or steel constructions near by. In this case the drone will give you a message to calibrate the compass in order to launch ... but if you do that every thing goes heywire once airborne & away from the interference. The drone can't anymore hoover depending on that it doesn't know the direction anymore & by that it can't correctly compensate to stay in place as it doesn't know in what direction it shall compensate. Usually this means that the drone starts to bank & turn quicker & quicker, stick inputs in this situation risk to make things even worse ... as the drone doesn't know the direction it is pointing. Things usually escalates pretty quick with a crash as a result. Try to google "toilet bowl effect" ...

One way to avoid this is to change launch location to be sure of that you aren't in a magnetic interfered area before you calibrate the compass due to a message in the DJI fly app. Also look on the drone marked as a triangle in the app ... is it facing to the right direction, if not this is the first sign that something is wrong with the compass, either that you actually shall calibrate or that you are in an area with interference.

My bet so far is compass error due to interfered area & you actually did calibrate (but as you say, you can't remember) ... and by that a pilot error. But perhaps more people will join in that can examine the flight log more in depth & point out a different reason (& explanation to way the heading differs 180 degrees between the video & log).

 

[Enrico BBB]

I can only interpret what I see ... according to your video the drone crashes to the right but according to the flight log it crashes with the left side of the drone first (look at the drone triangle in my earlier attached pic). For me that indicates a 180 degree compass error. You launched in a place surrounded by a high steel fence ... & under that rubber on the ground it perhaps was a steel plate or reinforcements, all highly magnetic.

How to get an compass error ...

Perhaps you stored the drone close to an magnetic object & by that magnetized it ... or you tried to launch in a magnetic interfered area, steel reinforcement or electrical installation close under ground or steel constructions near by. In this case the drone will give you a message to calibrate the compass in order to launch ... but if you do that every thing goes heywire once airborne & away from the interference. The drone can't anymore hoover depending on that it doesn't know the direction anymore & by that it can't correctly compensate to stay in place as it doesn't know in what direction it shall compensate. Usually this means that the drone starts to bank & turn quicker & quicker, stick inputs in this situation risk to make things even worse ... as the drone doesn't know the direction it is pointing. Things usually escalates pretty quick with a crash as a result. Try to google "toilet bowl effect" ...

One way to avoid this is to change launch location to be sure of that you aren't in a magnetic interfered area before you calibrate the compass due to a message in the DJI fly app. Also look on the drone marked as a triangle in the app ... is it facing to the right direction, if not this is the first sign that something is wrong with the compass, either that you actually shall calibrate or that you are in an area with interference.

My bet so far is compass error due to interfered area & you actually did calibrate (but as you say, you can't remember) ... and by that a pilot error. But perhaps more people will join in that can examine the flight log more in depth & point out a different reason (& explanation to way the heading differs 180 degrees between the video & log).

I can tell you I didn't receive on the app any warning or request regarding compass calibration. I received only an advice about positioning the drone with it's backside in my direction. That's all.

The question is: if the compass calibration is so important why is the drone allowed to take off if I don't do it?

Not all the people are drone pilot, mavic mini is entry level, they should have done a sort of system that doesn,'t allow the drone to flight if something isn't properly set . No?


So do you think I won the Certificate of Idiot 2019 and I won't be covered by warranty?

 

[slup]

The correct compass calibration is really important ... this together with a proper gps lock & a proper IMU calibration is what makes your drone hover steadily in one place even though outside factors are trying to push your drone around. The drone knows exactly were it is & were it's pointing and can interpret how it should steer to stay in position & how to interpret your stick commands.

To my knowledge you can't take off with a message saying "calibrate ... something" at least I can't with my Mavic Air. But you can calibrate the compass anyway though ... & if you do in an interfered area things can happen, you are the only one that knows ... or if it's in the log somewhere .

And yeah ... DJI's marketing seems to be that the Mini is somewhat for beginners, like a selfie-drone. Don't agree fully ... it hasn't any obstacle sensors & the Fly app shows very little to the pilot ... like to much facts will only confuse but that also takes away the possibility to take wise decisions ... but once again, I have an Air, the things about the Mini is what I have seen on the web so far.

Warranty ..? Well that's mainly up to what DJI decides, they will for sure dig deep into both the drone remains and available logs. The only thing you can do is to yourself (with the help of someone here on the forum) bring up true facts from the log that clearly say that something failed without you doing anything to create the situation.

 

[Enrico BBB]

The correct compass calibration is really important ... this together with a proper gps lock & a proper IMU calibration is what makes your drone hover steadily in one place even though outside factors are trying to push your drone around. The drone knows exactly were it is & were it's pointing and can interpret how it should steer to stay in position & how to interpret your stick commands.

To my knowledge you can't take off with a message saying "calibrate ... something" at least I can't with my Mavic Air. But you can calibrate the compass anyway though ... & if you do in an interfered area things can happen, you are the only one that knows ... or if it's in the log somewhere .

And yeah ... DJI's marketing seems to be that the Mini is somewhat for beginners, like a selfie-drone. Don't agree fully ... it hasn't any obstacle sensors & the Fly app shows very little to the pilot ... like to much facts will only confuse but that also takes away the possibility to take wise decisions ... but once again, I have an Air, the things about the Mini is what I have seen on the web so far.

Warranty ..? Well that's mainly up to what DJI decides, they will for sure dig deep into both the drone remains and available logs. The only thing you can do is to yourself (with the help of someone here on the forum) bring up true facts from the log that clearly say that something failed without you doing anything to create the situation.

I don't know. I'd buy another one but I am a little scared about what happened.

I can't know if somewhere exist or not interference, I am not a radio receiver or something like that. I can't know if some walls could contain iron or steel or anything else. I can't know if someone is broadcasting a pirate radio station or others similar ... I think the app should have some filters, some alarms that in this kind of situation blocks any kind of take off.... Or, if it happens when flying the drone should slowly land where it is.... It shouldn't start gaining speed like crazy.... Mine was in C mode and started flying at high speed .. everything happened in 4 seconds.... Someone could have been injured... Really too dangerous ..

 

[Enrico BBB]

I don't know. I'd buy another one but I am a little scared about what happened.

I can't know if somewhere exist or not interference, I am not a radio receiver or something like that. I can't know if some walls could contain iron or steel or anything else. I can't know if someone is broadcasting a pirate radio station or others similar ... I think the app should have some filters, some alarms that in this kind of situation blocks any kind of take off.... Or, if it happens when flying the drone should slowly land where it is.... It shouldn't start gaining speed like crazy.... Mine was in C mode and started flying at high speed .. everything happened in 4 seconds.... Someone could have been injured... Really too dangerous ..

Even if I made up a mess with settings (even if, but that's not true, At least not completely), drone is not allowed to fly without control like a crazy rocket because.... If it hits a person, who pay? What kind of damage could result? Dji could have had serious problems in that case.... Cause the drone get out of control (I doesn't matter who is faulty) and it act like a weapon without any control... It is too dangerous... It can gain speed that way... Something like this CAN'T HAPPEN. In this case drone should proceed slowly and land slowly! It NEVER should gain speed! So dangerous! Can you understand what I wanna say?

 

[slup]

Yeah ... understand your view point, but the thing is that not even the Mavic Mini is a toy & absolutely not totally fail safe & suitable to be handled without proper knowledge.

I don't firmly know how things is shown in the DJI Fly app for the Mini, but I'm sure it's similar tools there as in the DJI Go 4 app that I have for my Air ...

This shows me all about compass interference in the location that the drone are located ...


And regarding possible signal interference that can affect the connection between remote & drone I have this menu ...


I fully agree with you that a crashing drone can be really dangerous ... but so can a car with an unsuitable driver. The responsibility always fall on the operator if the crash reason is pilot error, you can't say that you didn't read the manual or flew in an unsuitable place without knowing & damaged either property or humans. (That's why you have insurances).

Myself bought my first drone ever this summer ... didn't launch for a week due to reading manuals, checking out YouTube & reading forums. Once fully sure about every function, every risky thing to do I launched for the first time in a big free football field without anything to hit or damage. Tried then out one function at a time until I was completely sure how everything worked. Went through all quick shoot modes, learnt how the RTH function worked, checked brake distances and so on ...

My 2 cents ...

 

[Enrico BBB]

Yeah ... understand your view point, but the thing is that not even the Mavic Mini is a toy & absolutely not totally fail safe & suitable to be handled without proper knowledge.

I don't firmly know how things is shown in the DJI Fly app for the Mini, but I'm sure it's similar tools there as in the DJI Go 4 app that I have for my Air ...

This shows me all about compass interference in the location that the drone are located ...
View attachment 87883

And regarding possible signal interference that can affect the connection between remote & drone I have this menu ...
View attachment 87885

I fully agree with you that a crashing drone can be really dangerous ... but so can a car with an unsuitable driver. The responsibility always fall on the operator if the crash reason is pilot error, you can't say that you didn't read the manual or flew in an unsuitable place without knowing & damaged either property or humans. (That's why you have insurances).

Myself bought my first drone ever this summer ... didn't launch for a week due to reading manuals, checking out YouTube & reading forums. Once fully sure about every function, every risky thing to do I launched for the first time in a big free football field without anything to hit or damage. Tried then out one function at a time until I was completely sure how everything worked. Went through all quick shoot modes, learnt how the RTH function worked, checked brake distances and so on ...

My 2 cents ...

I have never seen a car completely not responding at any input, gaining speed by itself.

Now, a drone, due to 1.000reasons can get out of control BUT, it was in C mode so it can't reach 40mph as it happened ok?

It's not allowed to change directions and to gain speed. If something go wrong it has to turn on a safety mode which do not allow it to raise speed. It has to stand where it is and to land slowly, even if in the ocean, in a forest or wherever. If it goes like a crazy rocket could kill someone... It's not a pilot matter... I could have done anything to stop it. How could be a crash on someone's face at 40mph? Dji has a security problem. How can a user forecast this kind of things? How could I imagine that if I forget a setting I could run a rocket in the sky? Please ...

 

[slup]

Understand your frustration fully but these machines maneuvers by means of sensors, and it is outputs from them the software take decisions on what to do. If someone of the sensors tells the drone wrong values it perhaps can't measure the speed correctly for instance... so yes the speed can become higher no matter of your chosen mode if a certain sensor is messed up.

Plain speaking... if you "blindfold" the drone by denying it sensor values or correct values it don't know what's up or down, left or right, or were north is. If this happens no matter of which the reason is you end up with a really confused drone making really odd stuff usually ending up in a crash.

The only way to prevent this is to learn the logic behind & know where the limits are.

How to design a safety mode to do the right thing if the drone have the wrong sensor outputs ?

 

[Enrico BBB]

Understand your frustration fully but these machines maneuvers by means of sensors, and it is outputs from them the software take decisions on what to do. If someone of the sensors tells the drone wrong values it perhaps can't measure the speed correctly for instance... so yes the speed can become higher no matter of your chosen mode if a certain sensor is messed up.

Plain speaking... if you "blindfold" the drone by denying it sensor values or correct values it don't know what's up or down, left or right, or were north is. If this happens no matter of which the reason is you end up with a really confused drone making really odd stuff usually ending up in a crash.

The only way to prevent this is to learn the logic behind & know where the limits are.

How to design a safety mode to do the right thing if the drone have the wrong sensor outputs ?

Thank you.

When the drone got crazy I saw on the screen a red message "sensor error"! Could it be a sensor failure? Or it's a consequence of the compass setting?
Is it visible on the LOG?

 

[slup]

Thank you.

When the drone got crazy I saw on the screen a red message "sensor error"! Could it be a sensor failure? Or it's a consequence of the compass setting?
Is it visible on the LOG?

From what I can tell the drone have already smacked into the building when the first error occurs ... "Not Enough Force/ESC Error". Have circled in the position for the first error message in the pic.

From the Airdata view it looks like the drone hit the building around mark "E" ... and had at that time reached it's highest speed, after that the barometer altitude rapidly goes down.

Can also see (confirm) that you didn't do any disastrous right stick inputs making it bank sideways (that if you had the sticks to mode 2) ... just some erratic left stick inputs once the drone started to fly away (probably made in panic...).

The only suspicious is what I mentioned before ... your video shows the drone bank right & crash but the log says it banked left. All this indicate a compass error by approx. 180 degrees. Why the compass was offset is another story ... usually that happens when a compass calibration is carried out in an magnetic interfered area.

 

[Prismatic]

i think this is the file we need.... isn't it? thank you all for your precious help.

There are three analysts here whose opinions I would trust in this instance: @Meta4 (who has weighed in), @BudWalker, and @sar104 (already alerted). Few others.
Just my opinion.

 

[slup]

There are three analysts here whose opinions I would trust in this instance: @Meta4 (who has weighed in), @BudWalker, and @sar104 (already alerted). Few others.
Just my opinion.

Yeah, I agree ... those are the guys that have the knowledge to dig deepest into the logs & perhaps reveal something that I can't see in the "top level" Airdata views.

 

[Enrico BBB]

Ok, waiting for the guys then.

Meanwhile I'll buy a new one cause I can't wait til February...