I have just started the flight and before even making ang move using the control sticks, the drone flew away in very high speed (~ 50 miter in couple of seconds) and crashed into the water. Tried to control the drone but the control stick s were uresponsive.

Hi,

Best to get help is to uplload your flightlog for this flight.

use this link > https://www.phantomhelp.com/LogViewer/Upload/

post the uploaded link on here, or just put a cloud link to your log one here.

cheers
JJB

Uploaded the flight log.

https://www.phantomhelp.com/LogViewer/N5D0KYLMIG6QIO5D4DT4

Never fly without satellites locked.  I wait for at least 10!
Your bird didn't know where it was when you took off.

ffgf

It was just start of Auto take off. Also even without moving any control it suddenly flew away in extremely high speed, it could have caused some serious injury.

Also since this is happened without any input from the pilot, I am expecting DJI to provide a replacement.

mkh Posted at 10-24 08:57
Uploaded the flight log.

https://www.phantomhelp.com/LogViewer/N5D0KYLMIG6QIO5D4DT4

Hi,

In this log the craft landed normally....are your sure it is the correct  flightlog??

But in this log zero satellites during the entire flight, so Mini2 in OPTI mode.

cheers
JJB

JJB* Posted at 10-24 10:28
Hi,

In this log the craft landed normally....are your sure it is the correct  flightlog??

This is the correct log. I will try to upload the flight map view. Seems like not all the flight details captured in the log. The map view is clearly showing it to fly away in very high speed.
https://youtu.be/dM8q_Ly8U_0

mkh Posted at 10-24 10:46
This is the correct log. I will try to upload the flight map view. Seems like not all the flight details captured in the log. The map view is clearly showing it to fly away in very high speed.

well, the PhantomHelp link shows at the end a ForceLanding.....no fly away speed  in that log.

JJB* Posted at 10-24 11:33
well, the PhantomHelp link shows at the end a ForceLanding.....no fly away speed  in that log.

Here is the map view of the flight
-------
https://youtu.be/dM8q_Ly8U_0

mkh Posted at 10-24 11:35
Here is the map view of the flight
-------

oke, 19 sats and HomePoint recorded,  do open that PH link and see that that link is to a different flightlog.

so it is a yaw compass related fly away or an error to the motors.

Did you check before takeoff the compass heading in the flyapp map view to the actual heading of your drone ?

Video shows file date oct-23, uploaded log oct-7.
cheers
JJB

JJB* Posted at 10-24 11:39
oke, 19 sats and HomePoint recorded,  do open that PH link and see that that link is to a different flightlog.

so it is a yaw compass related fly away or an error to the motors.

It flew away immediately after auto take off..within few seconds …even before I can do anything.

mkh Posted at 10-24 11:49
It flew away immediately after auto take off..within few seconds …even before I can do anything.

yes, your video shows that....now the correct log to see what really happend.

JJB* Posted at 10-24 11:51
yes, your video shows that....now the correct log to see what really happend.

https://www.phantomhelp.com/LogViewer/1BVLY437WMOBXTNYIJCP

Here you go

SnitserNL Posted at 10-24 12:17
[view_image]

At this point the drone already flew away in very high speed and no controls worked.

I think you have a very good case with regards to your latest log view

mkh Posted at 10-24 12:29
At this point the drone already flew away in very high speed and no controls worked.

So you said already.

What direction was your drone facing when you powered up?
What was the surface the drone was sitting on when you powered up?

Labroides Posted at 10-24 16:08
So you said already.

What direction was your drone facing when you powered up?

Drone camera was facing forward.. it was on a large stone surface.

Hello there mkh. I am sorry for the trouble this has caused and thank you for reaching out. Since this unfortunate incident happened and to your DJI Mini 2. I would recommend for you to contact our DJI Support Team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. We will do there best to help and will give out the best resolution for this issue. Again I am sorry and thank you.

DJI Stephen Posted at 10-24 16:40
Hello there mkh. I am sorry for the trouble this has caused and thank you for reaching out. Since this unfortunate incident happened and to your DJI Mini 2. I would recommend for you to contact our DJI Support Team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. We will do there best to help and will give out the best resolution for this issue. Again I am sorry and thank you.

I have created a case .. https://repair.dji.com/mycase/casedetails?CaseNo=CAS-7492092-G9P1T1

Thanks.

mkh Posted at 10-24 16:14
Drone camera was facing forward.. it was on a large stone surface.

Drone camera was facing forward..
That's not helpful.
It's pretty hard for the camera to face any other way.

What compass direction was the drone facing?

Ow….
That was really unfortunate….

Hope it will be fixed soon

mkh Posted at 10-24 12:02
https://www.phantomhelp.com/LogViewer/1BVLY437WMOBXTNYIJCP

Here you go

Hi mkh,

After takeoff the compass heading slowly changed value.
At take off heading : 152 degrees, changing anti clockwise to the opposite heading...see your data in my chart.
Wich heading was your drone facing at startup ? facing toward the water (hdg approx 150-160) or facing towards land (340 or so...)

When the compass value is changing directly after takeoff ; this indicates to a yaw/compass error, as the corrections made to the motors are sent to the wrong motors : fly away.

Just after takeoff 2 warnings:
1- Aircraft max power load reached. Decrease altitude and fly with caution. If this issue persists; land immediately.  Max power load reached. Fly with caution.
2-  Motor error. Check propellers and fly with caution.
Normally with a compass fly away speed increases to the max, that is why max power load messages are in the log.

So IMO the yaw/compass error is the cause of the fly away.

BUT #2 After takeoff the vertical speed indicates a negative value, as it it is decending while height did increase.
Baro height after the initial climb at takeoff went into large negative number, up to minus 267 meter!
This can happen as the IMU is in error too....

Hope that DJI can make a good assesment, if there is more than a compass error (often a user mistake) than mayby a warranty claim.

As said earlier, the most important check before takeoff is to check if the blue drone arrow in the flyapp map view shows the same heading as the actual heading of your drone.
If not the same : do not fly.

cheers
JJB

mkh Posted at 10-24 18:02
I have created a case .. https://repair.dji.com/mycase/casedetails?CaseNo=CAS-7492092-G9P1T1

Thanks.

Thank you for your information. We will keep an eye on your case. Sorry again for the incident caused.

JJB* Posted at 10-24 23:05
Hi mkh,

After takeoff the compass heading slowly changed value.

Thank you for the insights, but I am still wondering why it would fly away without any pilot input? For any type of system malfunction, shouldn't it either hover or fall down rather fly away in extreme high speed. It could have seriously injure some one.

mkh Posted at 10-25 05:02
Thank you for the insights, but I am still wondering why it would fly away without any pilot input? For any type of system malfunction, shouldn't it either hover or fall down rather fly away in extreme high speed. It could have seriously injure some one.

Hi,

To keep a drone in a steady hover it need 2 type of data ; GPS and Compass.

Try to make it clear for you.

- Put your drone in front of you at a table, camera facing you, its is flying there...
- Push it backwards, away from you, push back was the wind....
- Position drone is changed (GPS data), need to go forward to correct position
- Knowing the correct compass heading ; it now know wich motors to give more power to fly fwd

- BUT now assume that compass drone is 90 degrees offset to the real heading at your table (camera still facing you)
- push it back again
- to correct it back to the original position other motors get more power., now its flying 90 off the push back position, needs more correction, more power, etc etc  = fly away

That is why the MOST important check for DJI drones is to check compass before takeoff !

cheers
JJB

mkh Posted at 10-25 05:02
Thank you for the insights, but I am still wondering why it would fly away without any pilot input? For any type of system malfunction, shouldn't it either hover or fall down rather fly away in extreme high speed. It could have seriously injure some one.

For any type of system malfunction, shouldn't it either hover or fall down rather fly away in extreme high speed.
Because it couldn't hover.
Your drone was trying to hover, but with it's gyro sensors initialised with incorrect compass data, every small move it made to get back in position, put it further away ... so it corrects again and gets further away , over and over many times each second.

Labroides Posted at 10-25 06:57
For any type of system malfunction, shouldn't it either hover or fall down rather fly away in extreme high speed.
Because it couldn't hover.
Your drone was trying to hover, but with it's gyro sensors initialised with incorrect compass data, every small move it made to get back in position, put it further away ... so it corrects again and gets further away , over and over many times each second.

As far as I remember the compass reading in the app display was not showing any anomaly. Otherwise it should have alerted before or during auto take off. After auto takeoff, It hovered for few seconds like normal hover before it flew away without any input. Why would it hover normally with a compass issue ( if we assume that is the case) and then suddenly flew away without any pilot input.   

There should be an option at least, to select "Do not fly away even if you (the drone) believe you are disoriented"
It's incredibly stupid of DJI to assume that their "intelligence" is superior to the pilot in-place!

Johnny_J Posted at 10-25 07:27
There should be an option at least, to select "Do not fly away even if you (the drone) believe you are disoriented"
It's incredibly stupid of DJI to assume that their "intelligence" is superior to the pilot in-place!

I agree, it should not allow to Auto take off if it realizes there is some issue with the compass or any other settings. Even after auto take off ( where it hovers above a small height) if it fell it will have less chances of damage or probability of losing it.

mkh Posted at 10-25 07:23
As far as I remember the compass reading in the app display was not showing any anomaly. Otherwise it should have alerted before or during auto take off. After auto takeoff, It hovered for few seconds like normal hover before it flew away without any input. Why would it hover normally with a compass issue ( if we assume that is the case) and then suddenly flew away without any pilot input.

well, the main question is : wich heading was the front of your drone facing on the ground before takeoff?

JJB* Posted at 10-25 08:09
well, the main question is : wich heading was the front of your drone facing on the ground before takeoff?

Towards the water (the direction I was facing), but it flew away in a trajectory towards ~ 90 degree left of the initial direction it was facing during auto take off  / hover. It crossed the water body and a road and fell into another water body.

A question for the likes of JJB and Labroides.
What is the situation if VPS is available?
Indoors my mini etc. fly perfectly well without GPS, relying on the VPS to hold position and are cm perfect. I assume the compasses are working to the drones' satisfaction as I have no compass warnings but your posts have me wondering what would happen if a compass was awry, that pressumes a drone would take off with a wonky compass.....will it?.

mkh Posted at 10-25 08:28
Towards the water (the direction I was facing), but it flew away in a trajectory towards ~ 90 degree left of the initial direction it was facing during auto take off  / hover. It crossed the water body and a road and fell into another water body.

Hi,

Shortly after takeoff drone moved in the direction approx 060.
But compass heading the opposite.

To fly back to yout start position, that means fwd pitch, wich it did!  see the pittch, roll and moving data.
But drone direction was 060 (so facing that direction), so more fwd pitch to correct...and more...

Typical yaw/compass error resulting in a fly away.

Hope that DJI find more in the log, baro height and vertical speed totally incorrect.



cheers
JJB

Sean-bumble-bee Posted at 10-25 11:03
A question for the likes of JJB and Labroides.
What is the situation if VPS is available?
Indoors my mini etc. fly perfectly well without GPS, relying on the VPS to hold position and are cm perfect. I assume the compasses are working to the drones' satisfaction as I have no compass warnings but your posts have me wondering what would happen if a compass was awry, that pressumes a drone would take off with a wonky compass.....will it?.

Indoors, without GPS but with enought light and good visual reference ; drone fly s in OPTI mode.
Not in ATTI, in OPTI mode braking does work ; if you release all sticks drone will stop and hover.
But when GPS and compass are available then it uses GPS for positioning.
And things goes wrong if compass/gyro`s are not in sync.

About the compass flying indoor ; never experienced myself indoor flying a compass error, not 100% sure if compass data is used in OPTI mode.Actually i do not think so, bc pretty sure that in OPTI mode no RTH is possible (wich needs compass data), plus ofcourse no GPS so so HP is set.

MINI has a IMO a 'stupid' place for the power switch!
I always keep my MINI steady horizontal (top up) and not moving at all when powering on.
Only seconds after power on (so initialisation of all systems is complete) i will put my MINI on the ground or do a hand takeoff.
After that a blue arrow compass check (map view) compared to the actual heading.

cheers
JJB

mkh Posted at 10-25 08:28
Towards the water (the direction I was facing), but it flew away in a trajectory towards ~ 90 degree left of the initial direction it was facing during auto take off  / hover. It crossed the water body and a road and fell into another water body.

The zip contains a simulation of your flight from the log data. Notice the difference between Gimbal Yaw (360) and the Mini2 Yaw(360). 2021-10-25-20-37-42.rar (1.73 MB, Down times: 15)

2021-10-25 Upload

Click on the file name to download attach

Thanks.
I have seen the odd compass warning indoors, when I have set the drone down near tools etc. (it doesn't seem to take much in the way of steel to upset it ) but I have never tried to fly it in that state, I have always calibrated it and pushed the tools etc. away. I do not remember if take off was prohibited.

"MINI has a IMO a 'stupid' place for the power switch! " I agree, especially with the camera/gimbal being only mm above 'ground level'.
That said, I often launch from my hand and have developed a habit of switching it on /off from underneath IF I can feel the button.


''But when GPS and compass are available then it uses GPS for positioning.'' taking that to mean when VPS, GPS and the compass are available I am inclined to disagree.
I think VPS over rides GPS positioning. The reason being, I have flown the Mavic Mini (MM) at night where the ground was too dark for the VPS to work and, in the same place and doing the same thing, the MM drifts 'much' more at night than it does in daylight when there is enough light for the VPS to work. In a night time, in the dark, hand catch I would have to either move my hand or walk a step or two as the mini performed the final descent. In daylight I can make the final descent with out moving my hand.

mkh Posted at 10-25 07:23
As far as I remember the compass reading in the app display was not showing any anomaly. Otherwise it should have alerted before or during auto take off. After auto takeoff, It hovered for few seconds like normal hover before it flew away without any input. Why would it hover normally with a compass issue ( if we assume that is the case) and then suddenly flew away without any pilot input.

As far as I remember the compass reading in the app display was not showing any anomaly.
Because there was no anomaly that the compass could detect.
The anomaly was in the direction that the magnetic interference rather than the strength of the magnetic field.

You almost certainly launched from an area close to something steel or magnetic interference.
If the compass identifies the magnetic field as much stronger than the earth's magnetic field, it will warn you.
But if the field is not stronger than the earth's magnetic field, but still enough to deflect the compass and give false directional data, there is no way for the flight controller to know of a problem.

Otherwise it should have alerted before or during auto take off. After auto takeoff, It hovered for few seconds like normal hover before it flew away without any input. Why would it hover normally with a compass issue ( if we assume that is the case) and then suddenly flew away without any pilot input.
When the drone launches and leaves the magnetic influence that  caused the problem, the compass starts to give correct directional data.
But the gyro sensor has been initialised with incorrect data and the drone has a big problem that it is unable to work with.
The drone knows that it is going off position and tries to correct as I explained in my previous post.

It's called a yaw error and similar cases get reported frequently.

Sean-bumble-bee Posted at 10-25 13:20
Thanks.
I have seen the odd compass warning indoors, when I have set the drone down near tools etc. (it doesn't seem to take much in the way of steel to upset it ) but I have never tried to fly it in that state, I have always calibrated it and pushed the tools etc. away. I do not remember if take off was prohibited.

I have seen the odd compass warning indoors, when I have set the drone down near tools etc. (it doesn't seem to take much in the way of steel to upset it ) but I have never tried to fly it in that state, I have always calibrated it and pushed the tools etc. away.
There's absolutely no need to recalibrate the compass in that situation.
There is nothing wrong with the compass that needs "fixing".
All that's needed is to power down, move the drone from the problem the compass is warning you of, and start again.


''But when GPS and compass are available then it uses GPS for positioning.'' taking that to mean when VPS, GPS and the compass are available I am inclined to disagree.
The problem isn't in the drone's ability to know it's position.
The problem is having a conflict between the directional data from the compass and gyro sensors.
The drone knows its position, but when it tries to move to correct itself, the trouble begins because the gyro sensors have been initialised with incorrect directional information.