Hello everyone,


In this thread, I would like to share a bad crash experience and the bad quality of the DJI customer services.
Let me explain why.


Situation



1) Take-off, then set up of the camera position. (during approx. 30sec)
2) Slow advance of the drone (not in sport mode)


3) Strange motor sound and altitude loss, then the aircraft speed raises abnormally. The aircraft doesn’t respond well to the remote.
I decide to make the drone come back as simply as possible. In reverse.

4) After a while, the aircraft finally change of way and seems to come back (in reverse).
But quickly the motors make noise and the speed increase.


I release the buttons on the remote control, but the aircraft continues to come with high speed in my direction.
I try to touch again the button to see if the aircraft behavior change, but too it’s to late...
5) The aircraft crashed into the wall behind me, just next to my face

Important note:
From 2 to 3, the spark displacement lasted 18 seconds. (in straight line) From 3 to 5, the aircraft displacement lasted 8 seconds. (in straight line)


In the aim to explain the situation to DJI, I create my own report to explain why I'm not responsible of the crash. (see attachment) Rapport_drone_v1.pdf (192.18 KB, Down times: 1)

2020-9-18 Upload

Click on the file name to download attach
own report
The whole problem comes to the automatic ATTI swtich (when GPS is weak).
I noticed that when ATTI mode happen, the motors power (=motors speed) highly increase, even if you are not in sport mode.
The result is that it's impossible to avoid a crash when it happened between step 4 and 5, especially 2 sec before the crash... Human reaction can't be so quick when you expect nothing...


See below the flight recording :

On the third graph:ATTi mode = 0
GPS mode = 1


We notice that
a) from 30sec to 43 sec everything is ok
b) at 43 sec ATTi mode automatticaly switch, then instantanelly the speed highly increase (more than the 2 m/s of the P mode)
We also notice that in GPS mode the Motor Power < Power motor in ATTI mode // (Tension is constant and P=UI),
It show that there is no wind because with wind the motors need to compensate, if they compensate, power increases.
It's not the case here. (I also have the flight video who show that in every mode the Spark stay in straight line, no deviation of direction)

c) at 48 second we see that I asked to the spark to flight in reverse (to not distabilize it) // Step 4 of my first drawing
everything become normal again cause we switch again in GPS mode

d) at 54 second (2 sec before the crash) ATTI mode switch automatically again, it's too fast and too late to react! Please note that at this moment, all the remote controls were released!!!
The spark (without wind) highly accelerates and crashes in the wall behind me, next to my face.
The fact that the aircraft flight just next to my face is important, because it show that there is no wind, come and go are on the same trajectory.



I sent all my observations to DJI.
Then after a lot of exchanges, they stay on their position, which is:
As the crash happens in ATTI mode, it's the customer fault.
See in attachemnt the DJI report.

(You will also notice that all the checkboxes are written in a sense where all the damage that can possibly happen are not due to DJI, funny right?)
Data Analysis Report.pdf (782.35 KB, Down times: 4)

2020-9-18 Upload

Click on the file name to download attach
DJI report

Last thing: in my User Manual, I noticed a verry interesting thing:
It seems that if you goes in ATTi mode on purpose you have to sign something saying that you will loose your warranty.
But nothing concernig the autoswitch in ATTI mode.??



To be noted: The notice extract, in the DJI report, has been updated by DJI.
Because I checked in MY manual, supplied with MY aircraft and the new text doesn't apprears anywhere.
Another proof showing there is something not clear with DJI ATTi mode... Why the update otherwise.
It's also interesting to note that SPARK models are not for sale anymore they have been replaced by Mini Mavick...

Please don't hesitate to share in case you had the same bad experience, without any help of DJI to repair the aircaft.
They refuse to use the warranty, it's a shame!!!

Thank you

Hi there, I'm so sorry about the accident, I have managed to get your case number via your forum account, according to the data analysis result, the accident was caused by the improper flight environment, so no warranty service provided.
However, I'd like to help you escalate your situation to our supervisor team, we'll have someone contact you within working hours. Thanks for your patience.

Improper flight environment?
Did you read what I explained?
The flight environment was pretty ok...

I have a DJI mail admitting that there is no wind, see below:

Dear Custmoer,
Thank you for your message.
Wind was just an example in which I wanted to illustrate how badly the loss of GPS and the kicking in of ATTI-Mode can and will affect your flight due to the lack of sensors and active balancing of the unit.

Thanks for sharing

Never_Again_DJI Posted at 9-19 02:25
Improper flight environment?
Did you read what I explained?
The flight environment was pretty ok...

Hi there, I fully understand your situation, your concern has been forwarded to the related team to follow up. If there is anything else I can assist you with, please feel free to let me know, thanks.

DJI Natalia Posted at 9-19 21:27
Hi there, I fully understand your situation, your concern has been forwarded to the related team to follow up. If there is anything else I can assist you with, please feel free to let me know, thanks.

And here is the compressed video of the flight showing the rectilinear trajectory without any problem related to the environment conditions: Video.zip (990.48 KB, Down times: 4)

2020-9-19 Upload

Click on the file name to download attach
video

Never_Again_DJI Posted at 9-19 22:31
And here is the compressed video of the flight showing the rectilinear trajectory without any problem related to the environment conditions:

Hi,

Sorry for your crash.  Do you mind to upload your flightlog, using this link > https://www.phantomhelp.com/LogViewer/Upload/

BTW  Spark (pilots) cannot be switched manual to ATTI.

cheers
JJB

Yes of course, See the flight log below.

Never_Again_DJI Posted at 9-20 02:29
Yes of course, See the flight log below.

Thanks, but i mean uploading not a screenshot.

There is more in the log to be seen, so if you like  use the link

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

cheers
JJB

JJB* Posted at 9-20 04:52
Thanks, but i mean uploading not a screenshot.

There is more in the log to be seen, so if you like  use the link

Good morning,

Find in attachment the whole file: 20-08-25-01-31-46_FLY115.zip (210.32 KB, Down times: 2)

2020-9-21 Upload

Click on the file name to download attach

Good morning too,

a data error in the CSV, but is it possible to use this link : https://www.phantomhelp.com/LogViewer/Upload/

Upload your flightlog.txt file into the link, after that post a link on here. (or sent your flightlog.txt in a zip)

cheers
JJB

JJB* Posted at 9-21 01:39
Good morning too,

a data error in the CSV, but is it possible to use this link : https://www.phantomhelp.com/LogViewer/Upload/

https://www.phantomhelp.com/LogViewer/L408HY8TGGUXGNTK1DHC

Never_Again_DJI Posted at 9-21 03:09
https://www.phantomhelp.com/LogViewer/L408HY8TGGUXGNTK1DHC

Hi,

Your flight was started in OPTI mode, no GPS satellites and no GPS signal reception.

In OPTI mode Spark is stabilized in position if the bottom sensor received signal, wich it did, but not the whole flight.

at 8 8.2 seconds in flight : message "Signal GPS faible. La précision du positionnement pourrait être compromise. Volez avec précaution."at 32s :  Altitude de vol maximum atteinte. Ajustez l'altitude dans les paramètres de contrôle si nécessaire.

this because height is limited if not flying in a GPS stabilized mode.

at 44 and 54s again : " Signal GPS faible. L'appareil est en mode Attitude et le vol stationnaire pourrait être instable. Volez avec précaution."

So whole flight in OPTI and, guess due to not enough ground reference, in ATTI !

In ATTI mode Spark will fly 'away', as there is nothing to keep Spark in a stabilized position (Hover)
Only to counter steer Spark will stop the motion, but this needs experience and free space for your Spark, it is somehow difficult to do!
Plus it needs a very quick reaction to steer and command the correct RC stick input.

Spark was never in a P-GPS mode, as the GPS reception during the whole flight was ZERO.
(P-GPS is shown, mayby wrongly decrypted from the txt file to csv file, or a DJI mistake)

Guess if you knew this all before, you had waited for sure to get a good GPS lock before starting this flight.

cheers
JJB

JJB* Posted at 9-21 05:44
Hi,

Your flight was started in OPTI mode, no GPS satellites and no GPS signal reception.

Thank you for the observations.
But I think we agree on the fact the problem remains the same.

All the flight was pretty much under my control, except for the last 2 seconds.
The aircarft was at few meters from me (maybe 1 or 2 meters) when suddenly ATTI modes comes back, and speed increased from nearly 2 m/s to more than 10m/s !
You will also agree on the fact that, as you said, at 8.2s the spark was in OPTI mode. (because next to me on the dirt road) .
But at the end, for the 2 last seconds, the spark was on the same position, just above the same dirt road.
Why hasn't the "OPTI" mode been activated?

So we finally agreed on the fact that it's impossible to avoid a crash in these conditions!
So it's not due to environment conditions or bad piloting! But it's due to the fact that when ATTI mode is activated, the speed increased highly, (even if no control buttons are pushed)

DJI Natalia Posted at 9-19 21:27
Hi there, I fully understand your situation, your concern has been forwarded to the related team to follow up. If there is anything else I can assist you with, please feel free to let me know, thanks.

Still no reply from DJI... Silent...
It's really quite,

maybe you count on someone else to do the job?

Never_Again_DJI Posted at 9-21 05:56
Thank you for the observations.
But I think we agree on the fact the problem remains the same.

Hi,

Guess we disagree a little.

DJI drones are made for flying in a GPS stabilized modes.
Flying in OPTI is taken a great risk, when for some reason craft enters ATTI ; well, almost 99% a loss of control and loss of craft if not flown in a wide open area free of obstacles.

You took the risk, and lost.

I have no idea why at the end it went into ATTI again, no reference or not enough for the ground sensor i guess.
Speed in the log in ATTI is often mis-calculated, but ofcourse it did speed up. But not sure about the speed values though.

a Pilot error ?  NO, just hard to act and control a Spark in ATTI...( i owned one, few times in ATTI and i have some experience....)
a Pilot error ? YES, if you take this risk.

DJI drones can go into ATTI, pilots should be aware of this and fly a mission such that the risk of entering ATTI is minimal.This means not to fly away in OPTI mode. (well, just my 2-cents)

So i do not think DJI will grant you a garanty.
cheers
JJB

JJB* Posted at 9-21 06:34
Hi,

Guess we disagree a little.

It's pretty surprising to see someone defending as much DJI.

Maybe you are the "someone" that DJI is waiting for.
But I think you are well connected to DJI.
Netherlands, same place as DJI repair center... What are the odds...
I say that, I say nothing...

Like you said. It was never written OPTI but GPS...
How would I know that DJI drones are not able to react properly (in ATTi).
I've never had  a drone that accelerates by itself (even the Banggood ones)!

Never_Again_DJI Posted at 9-21 06:47
It's pretty surprising to see someone defending as much DJI.

Maybe you are the "someone" that DJI is waiting for.

haha, nope  i do not work for DJI.
You probably will not believe me, never mind.  Just trying to be helpfull and explain your log.

BTW DJI logs are encrypted, so we will never know if the decrypting or DJI is wrong in their P-GPS.

EDITFound the reason [ not mode2 but mode3 on the RC ] why it accelerate so much ; the moment the drone changed mode into ATTI you were pushing 100% stick forward.This in ATTI will accelerate the SPARK to max speed!  (max angle down), see your data in the chart.
same for the last rapid speed increase, full aft stick = 30 degrees up = going for high speed!

All the best,
cheers
JJB

JJB* Posted at 9-21 07:00
haha, nope  i do not work for DJI.
You probably will not believe me, never mind.  Just trying to be helpfull and explain your log.

My remote was in P mode and never in Sport mode! I prove this point in my first message. And I will appreciate you stop saying wrong things without knowing!!



You stop the data before the event...
It appears the 2 last seconds...
Your analysis are just wrong...
I think you didn't notice but I use the full DAT file for my analysis. So I have the whole data...



Quick demonstration:

On the way:
Average speed :2 m/s
Time: 47-30 =17sec

Distance=2 x 17 = 34 m

On the way back:
Time until crash=6 sec
Average speed = 34/6 = 5,7 m/s

When you know the main acceleration last 2 seconds.
The final speed is between 6 and 17 m/s...

Never_Again_DJI Posted at 9-21 09:44
Quick demonstration:

On the way:

Oke, in the log no distances ofcourse (no lat lon data)

see the reason why it accelerates in previous edited post, in ATTI mode craft will accelerate tot the max with max RC input and doesn`t stop when sticks are released.
That is how ATTI works.

Thank you but I perfectly know why it accelerates, it's clearly explained in my first message...

The real question is why it accelerate so much!!

Questions for DJI only:
1) Give me one technical explanation on the fact that when ATTi mode activates the speed is multiplicated by 5? (Especially when all the remote buttons are released)


2) Give me the technical reason to explain why OPTI mode didn't worked the 2 last seconds (the ground was at 2m max from the drone)

Never_Again_DJI Posted at 9-21 10:37
Thank you but I perfectly know why it accelerates, it's clearly explained in my first message...

The real question is why it accelerate so much!!

a correction on your chart, you forgot the roll input ; this started the drone to accelerate at the end

JJB* Posted at 9-21 22:52
a correction on your chart, you forgot the roll input ; this started the drone to accelerate at the end

Could you stop trolling my post ?? It's obvious you are DJI...

As usual, your argument don't works, it will imply that when you ask to the drone to go on the left or on the right (slightly) he will accelerate (but not on the left or on the right, but straight)!

Oh my god, yes sure!!!!

Never_Again_DJI Posted at 9-21 23:08
Could you stop trolling my post ?? It's obvious you are DJI...

As usual, your argument don't works, it will imply that when you ask to the drone to go on the left or on the right (slightly) he will accelerate (but not on the left or on the right, but straight)!

Shame on you, questioning the integrity of JJB*!
One of the forum's most valuable members.

Never_Again_DJI Posted at 9-21 06:17
Still no reply from DJI... Silent...
It's really quite,

We are sorry for the delay, I noticed that the teams had contacted you with the solution and you'd replied to the email, we will ask the teams to handle the case asap in working hours.

Haggi Posted at 9-22 14:21
Shame on you, questioning the integrity of JJB*!
One of the forum's most valuable members.

You mean the DJI puppet ?
Yes, it seem's really strange he stops to interact at the exact moment when DJI announced me by email that they accepted my request for financial support…

If I wasn't right, do you really think I would have gotten anything from DJI?
think about that ;)

Good bye!

Never_Again_DJI Posted at 9-24 02:49
You mean the DJI puppet ?
Yes, it seem's really strange he stops to interact at the exact moment when DJI announced me by email that they accepted my request for financial support…

u r thick bro. take your lumps and move on. you crashed your drone and are now blaming everyone else? IMHO seems a bit narcissistic. Its a SPARK buy another and move on. They are pretty affordable these days. but next time wait to launch until at least 9 satelites are locked. flying a spark in opti with the remote on config3 is like playing russian roulette.

Brucestephen Posted at 9-24 08:22
u r thick bro. take your lumps and move on. you crashed your drone and are now blaming everyone else? IMHO seems a bit narcissistic. Its a SPARK buy another and move on. They are pretty affordable these days. but next time wait to launch until at least 9 satelites are locked. flying a spark in opti with the remote on config3 is like playing russian roulette.

Remote was in mode 2 (slow mode)
It's written at least 4 times...

slow mode is TRIPOD MODE. not mode 2 on the controller. controller mode doesnt control the speed, your sticks and the flight mode of the aircraft dictate this so it really doesnt matter what position the remote was in. this has happened to me but i was in an open space and I didnt crash. next time be more patient with gps lock or reserve enough obstacle free area where the drone can be maneuvered properly. when i get a atti switch mid flight i go dead stick so i can see how the aircraft is reacting to current environment. this takes a second or two where the aircraft does its thing I wait and react to the drone, without extra space or altitude this is very difficult.