Hi folks, I had a flyaway Saturday and lost my connection to the drone, from the "Find My Drone" function I found a coordination so I went to the location hoping I could find my drone, with no luck.
After coming back home, I pulled out the flight record from my phone and checked it on Airdata.com, realized at that location, the drone was 20 meters high in the air.

Based on the manual, I have heard the mini would activate the RTH function, but before I lost the connection, I had tried to activated the RTH, all I got was the strong wind warning and it could not be done.

From the flight record I realized when I totally lost my signal, at the same time the flight log said the battery was at the maximum distance, is it the possible reason why I lost my signal?

Does anyone have the experience of this type of situation? Was there any chance the drone lost signal, and it couldn't RTH so it had landed somewhere?

Any input would be appreciated!

Here is the log I have put on airdata.comhttps://app.airdata.com/flight/e ... 92e/GENERALOverview

Generally if the drone has lost signal to the RC it would RTH if set to do so in the app but in your case if you was getting strong wind warnings the drone must have been fighting winds to get back hence it did not make it. if you post your flight log here some guys might look at it and provide a deeper insight as to what happened.

Suren Posted at 9-28 22:19
Generally if the drone has lost signal to the RC it would RTH if set to do so in the app but in your case if you was getting strong wind warnings the drone must have been fighting winds to get back hence it did not make it. if you post your flight log here some guys might look at it and provide a deeper insight as to what happened.

Thanks, will put the log on.

I doubt if it was trying to come back, since I tried to activated but it was canceled automatically by the drone.

fans16b87ee6 Posted at 9-28 22:22
Thanks, will put the log on.

I doubt if it was trying to come back, since I tried to activated but it was canceled automatically by the drone.

I don't have the link anymore for phantom helper but maybe someone will post it here. it gives a better description of the flight logs and events

Mate - This app was screaming at you that the wind was too much for that drone from the time you took off, you should have not flown.

This part here shows the RTH engaged but the esc errors shows this poor little drone battling against some strong winds, at the height you was the gusts must have been heavy

Suren Posted at 9-28 22:32
Mate - This app was screaming at you that the wind was too much for that drone from the time you took off, you should have not flown.

[view_image]

Yeah, I learned the lesson the hard way, for the beginning I was trying to keep it low and right above me, and drone was still until around 2 minutes, suddenly I assume the wind caught it, then all the pitch back or roll to side operations were not working. There was a lake below so I was afraid of falling into the lake so I was trying to move to the side, and waited until it had passed the lake then lower the drone, unforturnately I didn't have enough time to low it all the way down before I had lost the link.

I did a IMU calibration before take off, I don't know if that made some difference.

fans16b87ee6 Posted at 9-28 22:40
Yeah, I learned the lesson the hard way, for the beginning I was trying to keep it low and right above me, and drone was still until around 2 minutes, suddenly I assume the wind caught it, then all the pitch back or roll to side operations were not working.

I did a IMU calibration before take off, I don't know if that made some difference.

A bit of an expensive lesson, but you said you know the location of the drone, go get it and be careful the next time. Use UAV Forecast to let yo know if weather is good to fly.

Suren Posted at 9-28 22:44
A bit of an expensive lesson, but you said you know the location of the drone, go get it and be careful the next time. Use UAV Forecast to let yo know if weather is good to fly.

I had been searching the drone for a few hours without finding anything, then I realized the location I had on the App was the last location the drone communicated with the controller, 20 meters in the air.
So now I wish to get some help guessing the trend of the drone, then go and look for it.

fans16b87ee6 Posted at 9-28 22:46
I had been searching the drone for a few hours without finding anything, then I realized the location I had on the App was the last location the drone communicated with the controller, 20 meters in the air.
So now I wish to get some help guessing the trend of the drone, then go and look for it.

JJB is normally good at that, hopefully he can tabulate a location with the direction of the wind. Maybe send him a PM to look at your thread.

Suren Posted at 9-28 22:50
JJB is normally good at that, hopefully he can tabulate a location with the direction of the wind. Maybe send him a PM to look at your thread.

Thanks for the advice, I'll try to find how to PM him. I am still new to the forum.

fans16b87ee6 Posted at 9-28 22:58
Thanks for the advice, I'll try to find how to PM him. I am still new to the forum.

Cool bananas

Hi,

Had a look at your flight too, too much wind for your MM this day.

It is hard or impossible to give a good estimate where it has landed/crashed (at the orange marker)

At the end your MM was at a height of 19 meters, drifting away approx heading 060.
Last speed (height 18) 5.5 m/s but before that about 9 m/s. (height 30).

If MM had the power to keep the height steady than it will drift further, batt level 66%.
In my calculation MM will fly for 670 seconds before landing, distance drifing away > 5 km.

See the chart, if MM drops in height it will crashed into the hill. (or high trees ...)

Guess it is finding a needle in a hay-stack.

How much wind?  well,  if you fly your MM 100% stick forward in sport mode and it drift backwards with 7.4 m/s...Normally in sport mode a MM reach a pitch anglee down of 25-30 degrees, your MM only about 20 degrees.
Less power to speed up but to keep height steady.
Must be about 14 m/s headwind flying at 70 meters height.

cheers
JJB

JJB* Posted at 9-28 23:15
Hi,

Had a look at your flight too, too much wind for your MM this day.

Thanks for the replying!

Actually, the direction it flow to is a down hill, my take off place's altitude is at 1400m, the last recorded location is around 1355m, that means the MM was in the air for around 70m high, the estimated location you got on the map, is around 1300m. It was on a farm land so I assume it won't be caught by any tree when flying.

Do you think it could land itself before running out of battery? or lower its flight height since there was no signal from the controller or  chance of RTH?

JJB* Posted at 9-28 23:15
Hi,

Had a look at your flight too, too much wind for your MM this day.

Thanks JJB, I hoped you would come by this post, always a pleasure to see your analysis of logs

fans16b87ee6 Posted at 9-28 23:26
Thanks for the replying!

Actually, the direction it flow to is a down hill, my take off place's altitude is at 1400m, the last recorded location is around 1355m, that means the MM was in the air for around 70m high, the estimated location you got on the map, is around 1300m. It was on a farm land so I assume it won't be caught by any tree when flying.

It will fly until reaching low batt landing value.

In a RTH it will climb to the RTH setting (if flying lower than the setting), but at the end you lowered the MM to about 18 meters. At this height it will fly further.
18 meters ofcourse reference to the takeoff height.
Distance last known point to estimate landing position = 5463 meters!   not 1300m.
Updated the GE chart, now the distance are right at the bottom height part. (left of chart = last known position, richt side chart = 'landing' )
Third hill peak at 3300 meters is same height as takeoff height, so it should fly over that hill.Bit if it lowers height in flight due to lesspower, a area to check for your MM too.

cheers
JJB

JJB* Posted at 9-28 23:32
It will fly until reaching low batt landing value.

In a RTH it will climb to the RTH setting (if flying lower than the setting), but at the end you lowered the MM to about 18 meters. At this height it will fly further.

Sorry I didn't make it clear, I meant the altitude of marked locations are around 1300m high.

5km further would be in nowhere. It's hard to image how come it could go this far before really doing the mathematic.

Thank you again for the analysis

fans16b87ee6 Posted at 9-28 23:46
Sorry I didn't make it clear, I meant the altitude of marked locations are around 1300m high.

5km further would be in nowhere. It's hard to image how come it could go this far before really doing the mathematic.

i adjusted the speed to the last speed, than it will fly only for 715 secs - 3931 meter

JJB* Posted at 9-29 00:07
i adjusted the speed to the last speed, than it will fly only for 715 secs - 3931 meter

Thanks! These locations look easier than last estimated ones since they are in the farm.

One more question if you don't mind, the low battery auto landing time, is it a time that we can customize or the drone decides by itself?

fans16b87ee6 Posted at 9-29 06:21
Thanks! These locations look easier than last estimated ones since they are in the farm.

One more question if you don't mind, the low battery auto landing time, is it a time that we can customize or the drone decides by itself?

The critical low battery is 5% for a MM, cannot be changed.

But craft calculate time needed for safe landing....so when you fly at 500 meters height 5% battery level is too little for a safe landing, so it will start an autolanding at a value > 5%.  

cheers
JJB

Suren Posted at 9-28 23:31
Thanks JJB, I hoped you would come by this post, always a pleasure to see your analysis of logs

Hi Suren,

This is also a vey interesting flight.

https://forum.dji.com/forum.php?mod=viewthread&tid=225394

if only 'pilots' always check their compass before take-off   and wait for good GPS reception....

cheers
JJB

JJB* Posted at 9-29 07:49
Hi Suren,

This is also a vey interesting flight.

Thanks JJB, some pilots need to create a pre check before take off, I almost always check my emu and compass before take off then go to 6.2 meters up and leave there for about 10 seconds to see if any issues while checking compass again and ensuring RTH is set in app for low battery and RC disconnect. We cannot afford to be carless when so much of money is floating in the air.

Suren Posted at 9-29 09:43
Thanks JJB, some pilots need to create a pre check before take off, I almost always check my emu and compass before take off then go to 6.2 meters up and leave there for about 10 seconds to see if any issues while checking compass again and ensuring RTH is set in app for low battery and RC disconnect. We cannot afford to be carless when so much of money is floating in the air.

I did the same thing as you did, just before the wind gust took control of the MM, then everything went out of control.

What kind of the maneuver do you think is the best after it went out of control?  IMO I should run to the drone fast (it was blown into a private property and I don't want to trespass onto it) and lower it down before the signal connection went off.

JJB* Posted at 9-29 07:44
The critical low battery is 5% for a MM, cannot be changed.

But craft calculate time needed for safe landing....so when you fly at 500 meters height 5% battery level is too little for a safe landing, so it will start an autolanding at a value > 5%.  

Another lesson learned! Thanks!

fans16b87ee6 Posted at 9-29 15:59
Another lesson learned! Thanks!

fans16b87ee6 Posted at 9-29 15:59
I did the same thing as you did, just before the wind gust took control of the MM, then everything went out of control.

What kind of the maneuver do you think is the best after it went out of control?  IMO I should run to the drone fast (it was blown into a private property and I don't want to trespass onto it) and lower it down before the signal connection went off.

For me, I use the UAV app, if wind speed is more than my drone can fly in sport mode for example my drone can do up to 72km in sport and wind speed is 50 kmh, I would not fly, if I do have to fly I will keep it very low.

Suren Posted at 9-29 20:07
For me, I use the UAV app, if wind speed is more than my drone can fly in sport mode for example my drone can do up to 72km in sport and wind speed is 50 kmh, I would not fly, if I do have to fly I will keep it very low.

Yes that's true, I use UAV as well, it was 5m/s which I thought it was OK, I switched it to sport mode once it stayed in the air, but I didn't expect the gust came in so strong.

Once I realized MM was drifting, then no roll or pitch maneuver was working. That's my main problem.

I should like you said keep it low so I could fly it back to ground quick enough.

Always learn something new when bad things happen.

Hello there. I am sorry to read and to know that your DJI Mavic Mini was lost and thank you for reaching out. Since this unfortunate event happened I would recommend 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 check what happened to the said drone and will give out the best resolution for this issue. Again I am sorry for the trouble and thank you for your understanding.

DJI Stephen Posted at 9-29 20:39
Hello there. I am sorry to read and to know that your DJI Mavic Mini was lost and thank you for reaching out. Since this unfortunate event happened I would recommend 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 check what happened to the said drone and will give out the best resolution for this issue. Again I am sorry for the trouble and thank you for your understanding.

Thank you, I have reported and have a case number now.
Waiting for the email.

fans16b87ee6 Posted at 9-29 20:16
Yes that's true, I use UAV as well, it was 5m/s which I thought it was OK, I switched it to sport mode once it stayed in the air, but I didn't expect the gust came in so strong.

Once I realized MM was drifting, then no roll or pitch maneuver was working. That's my main problem.

Hi,

"Once I realized MM was drifting, then no roll or pitch maneuver was working. That's my main problem."

Your MM did react to all your input, see the chart.

At ID 1500 your yawed the MM to the home direction, full forward etc.
Problem is that due to to the wind it was drifting backwards (see the red line bottom chart)

What to do if wind takes the MM ;

Don`t wait to long for some action!
If possible lower height,
Yaw MM towards home direction, **
In sport mode fully forward,
Check distance decreases in the app ; if not, find a spot to land before loosing connection.

** if you not sure how to yaw craft to the correct home direction, engage RTH, after turning to HP disengage RTH (than sport+100%fwd)
** or view map view and fly arrow onto the line-to-home

cheers
JJB

JJB* Posted at 9-29 22:56
Hi,

"Once I realized MM was drifting, then no roll or pitch maneuver was working. That's my main problem."

"Check distance decreases in the app ; if not, find a spot to land before losing connection"

This is so true
For recovering my drone I think my biggest mistake was not trying to land it before losing connection. if landed at least I could have the approximate coordination.

BTW JJB, what software do you use for getting all this informations? They are very useful.

fans16b87ee6 Posted at 9-30 04:24
"Check distance decreases in the app ; if not, find a spot to land before losing connection"

This is so true

Hi,

If you are a Window user, use FRAP.

https://forum.dji.com/forum.php?mod=viewthread&tid=203659

cheers
JJB

JJB* Posted at 9-30 04:34
Hi,

If you are a Window user, use FRAP.

Thanks for your work. I am downloading.

fans16b87ee6 Posted at 9-30 04:36
Thanks for your work. I am downloading.

if any question, just ask   how to contact me ; in FRAP.

JJB* Posted at 9-30 04:49
if any question, just ask   how to contact me ; in FRAP.

Thanks! FRAP is very useful!


Update. I talked to the farm owner, he told me this is the busy season for a farm but he would keep an eye on it.
Plus the grass is high at this time, so he suggested if he couldn't seen the drone in the next 2 months, then come back, most of the grass will be eaten by the cows by then and it will be easier to do a searching work.

fans16b87ee6 Posted at 10-1 07:09
Thanks! FRAP is very useful!

Thanks, i know FRAP is very usefull !   

If you load DAT data into FRAP then the wind data is also shown in few charts. Cool feature i must say.....

Hope you will find your drone one day.

cheers
JJB

fans16b87ee6 Posted at 9-29 20:51
Thank you, I have reported and have a case number now.
Waiting for the email.

Hi there. You are very much welcome and thank you for the reply. It is great to know that you were able to get in touch with out DJI support team for us to be able to help you further with regards to this matter and the proper resolution will be given after the assessment. Please keep us posted fro further help and thank you.