Hey there,

some days ago my DJI Mini 3 Pro ditched into the ocean despite I was pushing the up-stick.
Because I saw some whales nearby the beach I was very excited and ran to get my drone, quickly started it and took off from a place I used for take off on the days before. At this moment I was very excited about the whales, so I forgot to check if the drone had received GPS Signal.
After take off I flew the drone in sport-mode with full forward movement towards the whales above the ocean in an estimated height of about 3-5m. I did this kind of flying the days before without any problem, too.
Suddenly I received a red warning on the remote that the drone was flying in ATTI-Mode. I was surprised by that, because I never experienced this behavior before. At this moment I also realized the drone was loosing altitude without me pulling the stick to sink. As a countermeasure I pushed the left stick to raise the altitude but nothing happened. I thought that maybe through the steep forward angle the drone could not gain altitude so I stopped the forward movement of the drone by releasing the forward stick. After this I pushed the left stick again to gain height. But again nothing happened. I released the left stick again to give a new impulse to climb, but again nothing happened. this also was the moment I saw the drone ditching into the water. After some few seconds the signal to the drone was lost.
Sadly I could not retrieve the drone from the ocean so all I have is the flight log from the controller. I already uploaded it to Phantomhelp.com but I can't figure it out what happened wrong in this accident.

The whole flight only lasted about 40s, and everything went really quick.

Here is the link to my flight-log analysis.
https://www.phantomhelp.com/logviewer/0YAAXEGDWX1HW403HTPV/#

In this folder I uploaded the original flightlog .txt file and the exported .csv file.
https://www.dropbox.com/scl/fo/r8oe5hgtpf5inzj15mjyb/h?rlkey=hf4wud500yq0qhrecfl4jqefq&dl=0

I didn't file a fly-away case at DJI yet, because I first want to understand with your help what happened and what I may have done wrong, and if there may is a case of technical malfunction of the drone itself.
So I really appreciate your help. If you need any further information just tell me and I will supply them asap.

FYI:
This case is also a thread in the mavicpilots.com forum and can be found here:
https://mavicpilots.com/threads/dji-mini-3-pro-uncontrolled-sinking-leads-to-ditch-into-ocean-despite-countermeasures.143932/#post-1620231

I think I see the issue, sports mode and being so low, whilst in sports mode, the drone can drop in altitude, add that to any swell and its time for a swim. FYI, I also notice that you didnt wait for the homepoint to be recorded, this can be a recipe for disaster. especially above water

Hi there. We're deeply sorry to know the incident happened in your unit. If your unit is within the warranty period and after you decided that you will now request a Fly away case, feel free to contact our team at https://www.dji.com/support and we will do our best to help you determine the main cause of the incident. Should you have other inquiries, feel free to contact us. Thank you.

Hi,

You started this flight without a GPS lock, zero GPS sats!
After manual takeff your Mini3Pro used the vision to stablize.

Changed Flightmode to Sport.

At 18s into ATTI mode beacuse Vision lost its reference, so no more Vision assist to keep craft stable in the horizontal path.
In sport mode with full stick forward drone has difficulty to keep height steady, this in a GPS mode and apparanly also in ATTI mode.

Did you screen record your flight? So you can look back the warnings on the screen!

See my charts of your data.

As you already know ; always wait for the white GPS icon top left FlyApp screen. White = sat lock + HP set.

Flying away with a RED icon will result in ATTI mode when Vision gets out of range or cannot get good rererence to the surface below the drone, loosing reference above water happens more that loosing reference above a 'ground' surface.

In ATTI mode drone is not really limited in pitch up or down angles, your drone somepoint 40 degrees nose down at 100% forward stick, reaching max speed 16.1 m/s.Last speed in log before ATTI mode = 15.6 m/s.
Forward stick to zero and 100% up stick does not mean that drone will climb at the same time, it looses height before climbing.
Flying low above water, not enough free air below drone the recover and climb.
Height is controlled by the barometric sensor, also in ATTI mode. But height is not always steady with large and rapid RC inputs.

Let say you are flying at 10 meter baro height, in sport mode fly max forward to max aft stick with other inputs (not UP) as well. Do not think that a MINI3Pro will fly steady at exactly 10 meter during all those rapid RC inputs. In Atti mode attitude changes are more rapid than in a GPS mode.
Baro height indication can show incorrect height values due to rapid pitch changes as well. So height values in the log does not always show the actual height.

IMU error?  don`t think so, but wait for DJI to make their assesment.

cheers
JJB    [ Charts by FRAP ; the 'best' software for data and visual flightlog analysis (www.jjbfrap.eu) ]

Heyhey,

thank you all for your comments and analysis of this case!

I'm very sure there was no wave or something else that catched the drone. On the RC I saw the camera coming closer and closer to the water surface.

In flight I also hat the thought that the full forward pitch of the drone could be a reason for loosing altitude. Therefore I stopped to forward movement and tried to push it up.
@JJB* you mentioned I could not expect the drone to ascent after the break of forward movement. Why not? As I interpret the data I stopped the forward movement at about 29s and then tried to ascent, but nothing happened and the drone fell into the water. For me, right now, it sounds logical that you push the left stick up and the drone will follow this command. But I'm not an expert so I really love to learn more of these connections.

I now filed the fly-away case at DJI and wait for the response of the Supportteam. I will keep you updated!

matzeulrich Posted at 2-2 04:12
Heyhey,

thank you all for your comments and analysis of this case!

it sounds logical that you push the left stick up and the drone will follow this command.
Yes ... but in your case there was obviously a serious problem that meant the drone didn't respond to throttle input and kept descending.

matzeulrich Posted at 2-2 04:12
Heyhey,

thank you all for your comments and analysis of this case!

Hi,

at 17.9s from Vision to ATTI mode, speed 15.6 m/s, craft pitches down with 29 dgerees
In ATTI with full forward stick craft pitches more down, to 40 dgerees. speed same or more...
There is a limit to keep steady height with high pitch angles....
So drone starts to decsend.
If baro height indication is valid than drop from more than 10 meters. ....does not fits to your guessed height in your post.
Forward stick to zero at 29s. with full UP stick. Baro height from below zero to 5 meter.
Vertical speed does not show higher value than 0.2 m/s though.
UP stick for appox 5 seconds, so 5 meter baro height is not correct.

At 35.7 IR height indicates now 4.9, next records shows decsend.
Again full UP stick, after 2 secs positive value for rate of climb, but drone already at water level.

Why did your drone did not move direct UP with UP input?  must be combi of areodynamics and computing power drone....

From 40 degrees pitch down to no fwd input, in ATTI mode no braking, so speed only slows down a bit.
With 40 degrees pitch down software wants to keep drone height steady = more revs on motors.
Rapid from 40 degrees to flat pitch, still wants to keep height steady = less revs to the motors.
If this is not computed 100% correct than drone climbs or decsends...in your case it went down.
With UP stick it needs some time to stop the decsend and starts to climbs. For this you need some free height below the drone.


In my experience barometric height does not show always the correct changes in height due to press changes to the sensor caused by 'wind' through the drone.
Minor press changes shown at indicated height. ( 1 mbar = 8 meter difference ).

cheers JJB

These guys can work the data, anyone else can read your first post - you rushed the launch, then straight over the ocean

Today I received an answer from DJI regarding my flyaway case:

"Flight time: 2024-01-27 22:13:04 GMT+8

MC SN: XXXXX FLY(90) BAT SN: XXXXX


1. The aircraft worked under Sport mode after took off.

2. Flight Time T=00:40, Relative Height H=5.0m, The GPS signal was weak, affected its positioning accuracy, the aircraft came into contact with the water.


3. Please wait until the aircraft gained enough GPS signal to operate the aircraft.

As a result, it was determined that the incident was due to a non-manufacturing defect. We therefore regret to inform you that this case is not eligible for a free replacement under the warranty."


For me this isn't the answer I hoped for. I thought there would be some information about the cause that led to the ditching.
If it is really just my piloting mistake I would love the hear the specific reason to learn from this for the next time, but as far as I don't understand why the drone didn't react to my RC commands I can't believe that it's just a piloting error.
What do you guys think?

I answered the DJI mail with the specific questions about the drones missing reactions to my RC commands and why this could have happened.
Let's see

matzeulrich Posted at 2-6 13:24
Today I received an answer from DJI regarding my flyaway case:

"Flight time: 2024-01-27 22:13:04 GMT+8

Hi. Thank you for reaching out. I was able to find your ticket number using your Forum account. I will coordinate this with our relevant staff to provide additional assistance. Rest assured, this will be addressed and handled appropriately. Please keep an eye on your inbox for future updates. Thank you.

DJI Diana Posted at 2-6 17:53
Hi. Thank you for reaching out. I was able to find your ticket number using your Forum account. I will coordinate this with our relevant staff to provide additional assistance. Rest assured, this will be addressed and handled appropriately. Please keep an eye on your inbox for future updates. Thank you.

Thank you for your assistance!
If it's possible me and some other would love to see the corresponding .DAT File (in my case the actual filename is "FLY090.DAT") for a better self-analysis of the flight data.
Could you also help getting this file?

matzeulrich Posted at 2-7 01:52
Thank you for your assistance!
If it's possible me and some other would love to see the corresponding .DAT File (in my case the actual filename is "FLY090.DAT") for a better self-analysis of the flight data.
Could you also help getting this file?

You may need to PM this request to a mod or email the request directly to customer service.
I would also suggest that you stress you just want a copy of the DAT and that you are not asking for an analysis of the DAT.

matzeulrich Posted at 2-7 01:52
Thank you for your assistance!
If it's possible me and some other would love to see the corresponding .DAT File (in my case the actual filename is "FLY090.DAT") for a better self-analysis of the flight data.
Could you also help getting this file?

You're welcome. I have replied to your DM regarding this inquiry. Kindly check. Thank you!

matzeulrich Posted at 2-6 13:24
Today I received an answer from DJI regarding my flyaway case:

"Flight time: 2024-01-27 22:13:04 GMT+8

Hi,

I understand that you are not happy with the DJI analysis results, pilot error on not.
Only a remark about GPS and craft in contact with water.....
GPS is for the horizontal positioning, not for the vertical stability!

So the part "affected its positioning accuracy" needs more explantion from DJI.

But DJI will do a re-assesment, so hope for better explanation what really happend.

cheers
JJB

JJB* Posted at 2-8 12:11
Hi,

I understand that you are not happy with the DJI analysis results, pilot error on not.

Yes, I really hope for a more detailed and deeper explanation about what happened in this case!

Sadly DJI says, they can't send me the .DAT file, because they don't have it, too. They "only" have the flight log, that the RC uploaded to the DJI servers. I don't know what kind of file this is, but they say, it's not the .DAT file.
And they also mentioned, the .DAT files wouldn't be deleted after synchronization of flights with the DJI server. I can't test and control what is true about this topic, as I don't have my drone anymore. But I read a lot about the topic that .DAT files would be deleted after sync with DJI servers.

This morning I received an email from the DJI support team saying that the drone will now be replaced free of charge.
The reason given by the engineers is as follows:

"They [the engineers] have investigated whether there was a possibility that the drone may have had engine power saturation. Taking these considerations into account, they have decided to change the outcome to a free replacement under warranty as we truly value you as our customer."

Im very happy about the free replacement but the but the explanation for the possible crash is still not really clear to me. What can I imagine by a "engine power saturation"? Someone has an idea? I also asked this question back to DJI and wait for some more details.

matzeulrich Posted at 2-9 02:33
This morning I received an email from the DJI support team saying that the drone will now be replaced free of charge.
The reason given by the engineers is as follows:

Hi,

Good news, to get a replacement free of charge!

Lesson learned i guess, DJI drones operate best with a good sat lock, not with 40 degrees pitch down low over water loosing height due to rapid pitch changes.

So imo you are lucky that DJI is so generous, or mayby there was a power error.....  ;-)

Happy many landings,
Cheers
JJB

Today I received my replacement Mini 3 Pro.
Thanks to all, who helped me!