Hi, all,

This is my first post in this forum, so first of all I'm sorry if I ask any basic thing or if I forget to share important data.

Last Saturday I was flying my drone and --with enough battery and time left to come back--, it didn't. And when I realized what was happening it was already too late and it ended up crashing in the water. I do have a Refresh Care insurance, but I couldn't find the drone so it doesn't apply in this situation.

I wanted to know you opinion about this accident. I know for sure that I could have handled the situation better, I think I was just too relaxed thinking the drone would come back when I hit "Return to home" as it always did before. I started to notice something weird was happening, but I wasn't sure what it was and of course that's on me (please don't be rude, I acknowledge this in advance). But besides that, what I don't get is why it stopped coming back (around minute 12).

This is the log: https://www.phantomhelp.com/logviewer/74IG4XQ22FC63MATOCZL/

The weather seemed to be ok: https://app.airdata.com/share/OHfefT

Thank you all in advance!

Hello there. I am sorry for the trouble this has caused and thank you for reaching out. Since this unfortunate incident happened and you have lost the said DJI drone. 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 have a team that will do there best to help you and give out the best resolution for the said issue. Again, I am sorry for your loss and thank you.

My first thoughts is it was you error.
First i wouldnt adventure going that far with a lock on just 13 satellites. If it loses some of them things can go bad quickly, loose lock, and then is unable to return home.
Second when you hit return home button you only had 42% battery thats just insuficient. You should ALLWAYS return home with at least 55%/60% , i wouldnt risk with less than that. And you also have to take wind direction into account.

DJI Stephen Posted at 5-24 02:48
Hello there. I am sorry for the trouble this has caused and thank you for reaching out. Since this unfortunate incident happened and you have lost the said DJI drone. 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 have a team that will do there best to help you and give out the best resolution for the said issue. Again, I am sorry for your loss and thank you.

Hi,

First setting a RTH height to 120 meter is not a good idea, or you must have known some obstacles flying above that lake....

At 9m57s your MINI into RTH (flying at 49 meters height)
Distance out 1058 meters, MINI started to climb to 120 meters
At 54 meters lost contact and after some time it was connected again, now at 117 meters height
At 10m30s it started to fly home in RTH mode with a speed of about 8 m/s.
Batt level 39% that time, distance out 1016 meter.

BUT at 11m3s, at 827 meters away the speed towards home to ZERO!
Only few degrees pitch down, why ??
See my chart for all your data.
At 120 meters you did enter a no fly zone, warning shown earlier in your flight " Aircraft entered Geo Zone. Return to Home may be affected. Exit zone promptly",  this zone with a height limitation of 60 meter! That is the reason your MINI stopped forward flying!
At 18m33 at 55 meters height your forward input was "allowed" again, MINI started to fly forward.

If it was the wind at 120 height suddenly got stronger....nope, because that case the pitch down angles must be about 25 - 30 degrees down.Your MINI was not fighting against the wind, it was 'fighting' against a no fly zone.
Between 11m02 and 18m33 you lost 30% of unused battery %, no RC input to solve the problem.

If you had lower your craft earlier yourself under the 60 meters height limitation, and had applied full forward it could have made home.
See the distance line in the top chart.

Upper box = 150, lower box = 60 meter height limitation.

PS if you like post a cloudlink to your DAT file for this flight, its FLY058.DAT. (more data in there)
cheers
JJB

JJB* Posted at 5-24 03:18
Hi,

First setting a RTH height to 120 meter is not a good idea, or you must have known some obstacles flying above that lake....

Great analysis JJB*.  

JJB* Posted at 5-24 03:18
Hi,

First setting a RTH height to 120 meter is not a good idea, or you must have known some obstacles flying above that lake....

Thank you SO MUCH for your analysis.

I have to say I don't remember setting the RTH to 120 mts. I haven't used the drone in some months, but last time I remember I put it on 50 mts. No sure what to say here about that.

Regarding your analysis, I'm thinking about three things:

1) I wasn't looking at the screen all time but at the drone (which, I think, is what you are supposed to do, at least in theory), so I didn't see the "Entering GEO zone, RTH may be affected". Of course, I see that in the video now, but my question is: if that is so important, why the alert didn't stay on the screen? I had other important alerts before (winds, battery, propellers rotating too fast, etc), and they of course stay in the screen so you can see them. If that was that important, why it didn't stay visible so I could change the settings or the fly path?

2) If the drone can't RTH because of a Geo Zone situation, shouldn't it let me know somehow that's the case? Something like "Aircraft cannot RTH because of altitude limit". Because staying there at zero speed for so long without letting me know doesn't seem a very good software design.

3) Same idea: if my RTH altitude is higher than the height the drone can RTH, should it let me know something like  "your RTH is set to X meters, which is higher than the limit the aircraft can RTH"? I am a software developer, so if I had a situation where I have to stop a process because of something like that, I would let the user know, mostly thinking we are talking about a 500€ device (or it was when I bought it).

But as I said, thank you for your very clear and good analysis. And of course I am not the most experienced user of drones, as you can see. I wouldn't be in this situation right now if I were.

Cheers and thanks again.

You make excellent points - the software should always protect the user, to the point that it should have automatically changed the max return home altitude to the geo-capped height.  

I don't care for the way DJI handles the geo zone situation.  And I don't trust them to have my  best interest at heart.  I really like their hardware; but the software seems a lot like an after thought.  Sorry for your loss - my experience with my drones is always assume the worst will happen and keep one eye on the AC and one on the screen (LOL)
(also excellent analysys JJB, per usual).

fans87df5be5 Posted at 5-24 13:25
Thank you SO MUCH for your analysis.

I have to say I don't remember setting the RTH to 120 mts. I haven't used the drone in some months, but last time I remember I put it on 50 mts. No sure what to say here about that.

Hi,

My pleasure to help if i can....

1) Question for DJI to answer, but i agree ; for important warnings/messages the FlyApp should vibrate/sound a beep.  So remote pilots are alarmed to look at the screen.

But before flying a remote pilot must know the fly area for geo zones ect, high obstacles ect.
Part of the before flight checks, same for checking compass before flight and checked the RTH height setting.

2) Would be nice, but a remote pilot can or must check the RTH progress by checking the decreasing distances in the app. (if low at speed cancel RTH and swith to sport mode, or lower height if possible if drone is fighting head-wind or.....)
You did loose minutes of doing nothing, while the screen had all the info available.

3)
Would be nice, but you was informed in the FlyApp:
at 6m02 > "Max altitude reached (Altitude limit: 60m))"
at 6m30s > "Aircraft entered Geo Zone. Return to Home may be affected. Exit zone promptly

If you had known the geo-zones (60 and 120 limit) you probably had made different choices.

cheers
JJB

JJB* Posted at 5-24 23:05
Hi,

My pleasure to help if i can....

JJB,

Thank you again for your answer.
Maybe one difference between your previous analysis is that it was objective (you explained very very well what happened), but now we are in the realm of opinions. Basically, you are saying that my proposals would be nice, but that I should have known better. And even if I agree with that (of course, for instance, NOW I know better), the app should be better too. In particular:
1) We agree the alert should have remained there. That would have given me the opportunity to change things and learn from that. A flashing notification that disappears (we get tons of them all the time) cannot be one carrying that vital information.

2) The crucial point here is the drone stopping without letting me know why. You said that all the information was on the screen, and in a way you are right: but the main point was to let me know that at that altitude wasn't going to come back, and it didn't say that clearly and consistently. That's a very important alert the software didn't communicate as, for instance, "propellers rotating too far", that I got a couple of times and I landed the drone immediately and replaced the propellers right away. Instead, the drone stayed there burning battery (as a side point, it didn't actually stayed there: it starting drifting to the east, which is weird for a drone known for its stability).

I do have many other apps to check the conditions, but none of them would have informed me the RTH was stopped because of this.
I think it is important to emphasize that the reason I know now that the RTH was halted is because of YOUR analysis. Nothing in the log says that clearly. You did, because you have the knowledge and the experience, and you took the time to share that with us.

Maybe a good analogy is Google Maps: if the app tells you to use one route and the route is closed, of course you can tell the user "you should have known your way home", but that's the reason why I used Google Maps in the first place.

As I mentioned before, I am a software developer and I know for sure that if I make a client losing 500€ (or even 10€) because I stopped a process without him knowing it, he would be very very mad at me.

Sorry if I am too verbose here, but of course I am very frustrated by this situation.

Thank you once again for your knowledge and your time.

All the best,
Milton

fans87df5be5 Posted at 5-24 23:36
JJB,

Thank you again for your answer.

Another side comment: the disappearing "RTH to home may be affected" alert is a very very very light way of saying that the drone won't move.

fans87df5be5 Posted at 5-24 23:36
JJB,

Thank you again for your answer.

Hi Milton,

Yes, i agree with you that the FlyApp is far from perfect in getting important info to the remote pilot.
DJI is always improving their software and this is one subject in wich they can improve.

But having said that ; flying drones is not that easy, and the remote pilot is always in control & responsible, so FlyApp is a need to fly but will not covering all the things that can happen in a flight.....
Writing software is 20%, 80% of the time is needed for handling the exception/specials! or mayby 10/90.

About the drifting slowly to the east, i have noticed that too.
My explanatioon as follows ; to keep a steady hover position a drone must be free in all 4 directions to apply flight corrections. Hovering against the geo border means that a least one direction could not be used to make flight corrections, this resulted in a slow drift along the geo border to the east.

Understand your frustration, loosing a craft so close by in the water.
But few 'mistakes' were made by lack of expereince ; RTH height setting not checked before flight, fly area not checked, not reading warnings about geo zone and not able to fly back in a RTH mode, not checking RTH distance progress (basic knowlegde/practice if i may say so).

Cheers
JJB

fans87df5be5 Posted at 5-24 23:50
Another side comment: the disappearing "RTH to home may be affected" alert is a very very very light way of saying that the drone won't move.

MAY is correct, if the RTH height setting is below the geo zone max height than it will fly back without a problem.

JJB* Posted at 5-24 23:58
Hi Milton,

Yes, i agree with you that the FlyApp is far from perfect in getting important info to the remote pilot.

Hi, just a follow up: DJI reviewed my logs and they established that "Since there was no pilot error discovered, we determined to cover this case under warranty". Not sure if they say that just because of marketing (I mean, as they want to be nice with their customers) or because it's true, but at least they don't seem to think that if I made a mistake it was that important not to give me another unit.

fans87df5be5 Posted at 5-27 04:05
Hi, just a follow up: DJI reviewed my logs and the established that "Since there was no pilot error discovered, we determined to cover this case under warranty". Not sure if they say that just because of marketing (I mean, as they want to be nice with their customers) or because it's true, but at least they don't seem to think that if I made a mistake it was that important not to give me another unit.

well, i am happy for you ofcourse!  many great landings in the future with the replacment MINI2.

cheers
JJB

fans87df5be5 Posted at 5-27 04:05
Hi, just a follow up: DJI reviewed my logs and they established that "Since there was no pilot error discovered, we determined to cover this case under warranty". Not sure if they say that just because of marketing (I mean, as they want to be nice with their customers) or because it's true, but at least they don't seem to think that if I made a mistake it was that important not to give me another unit.

Actually amazing that you get a replacement because you wrote above, "I do have a Refresh Care insurance, but I couldn't find the drone so it doesn't apply in this situation." Sounds like you ALWAYS have to send the drone in, even if the log proves that it is on the seabed (at a depth of 4000 m next to the Titanic ;-) )

jonny007 Posted at 5-27 09:54
Actually amazing that you get a replacement because you wrote above, "I do have a Refresh Care insurance, but I couldn't find the drone so it doesn't apply in this situation." Sounds like you ALWAYS have to send the drone in, even if the log proves that it is on the seabed (at a depth of 4000 m next to the Titanic ;-) )

Hahaha, well, they did, which is pretty good