FYI if you ever fly near restricted airspace:

Checked B4UFly app, showed airspace was clear. Checked battery level after turning drone on, 60%. No alerts about interference, compass issues. Takeoff to about a meter before moving away from me through trees over cliff where ocean water was about 20m below. After about 30-60 seconds of flight time message appeared: “Landing Immediately”, I canceled and attempted to move the aircraft to no avail. Moments later the message appeared again: “Landing Immediately”, I canceled and attempted to move the aircraft to no avail. “Return to Home” appeared and since I’ve always RTH manually, myself, I canceled that as well. It would have had to navigate trees blocking a direct flight path back. At this point it is only about 10m away from me. It begins descending, I believe it did the RTH one more time but since I’ve always been able to over ride that in the past I canceled it. I tried to turn the camera down so I could see landing options, it did not respond therefore it slowly descended straight down into the ocean.

Reading the flight log I see at 39.5 seconds into the flight that I was in a no fly zone and it was landing immediately. Re checking the airspace I was at the edge of restricted airspace but not precisely in it. The GPS in the log gives an approximate location so I’m deeming that to be the reason it auto landed.

I suppose I've never flown that close to restricted airspace so I've not had experience with auto land, unfortunately it was an expensive way to learn the lesson.

The GPS in the log gives an approximate location so I’m deeming that to be the reason it auto landed.
Why do you think the GPS location data is approximate ??

Reading the flight log I see at 39.5 seconds into the flight that I was in a no fly zone and it was landing immediately.
The most likely explanation for the incident is that you launched before acquiring GPS.
If you launched from outside with GPS, the drone wouldn't have flown into the restricted area.
If you launched from inside with GPS, the drone would not take off.

If you post your recorded flight data, that might shed some light on what actually happened in your case.

Go to http://www.phantomhelp.com/LogViewer/Upload/
It has instructions to find the .txt file from your phone or tablet which you can upload to that site
Upload it and it gives you a summary of the flight data.
Post a link to that summary.

Or just post the .txt file

I can't comment on the airspace aspects of the flight but I would ask how long ago was the battery charged?
From my flying I am left with the impression that a days or weeks old charge does not 'hold up' under use as well as a recent charge that is few hours old.
If you have no concerns about showing the location of the flight then it might be useful to post the txt flight log and if you have it the DAT flight log.

Also no mention of home point being set.

Labroides Posted at 4-12 16:54
The GPS in the log gives an approximate location so I’m deeming that to be the reason it auto landed.
Why do you think the GPS location data is approximate ??

This message after takeoff is why I though GPS location is approximate (in the log file): Weak GPS signal. Positional accuracy may be compromised. Please fly with caution.

Log appears to have GPS throughout flight.

https://www.phantomhelp.com/logviewer/9U37U8CLSQYPTXWBENL3/

Thanks for helping me understand what went wrong.

Sean-bumble-bee Posted at 4-12 17:01
I can't comment on the airspace aspects of the flight but I would ask how long ago was the battery charged?
From my flying I am left with the impression that a days or weeks old charge does not 'hold up' under use as a recent charge that is few hours old.
If you have no concerns about showing the location of the flight then it might be useful to post the txt flight log and if you have it the DAT flight log.

60% battery on takeoff, 55% on crash. Charged 3 days earlier.
These show location from B4Ufly, it appeared good for takeoff, the other image shows an expanded view showing restricted airspace off shore, I didn't zoom out and see that at takeoff. It still seems to appear that I wasn't in restricted airspace unless that includes any water, this was over a small inlet. Not that I'm going to chance that in the future.




Flight log: https://www.phantomhelp.com/logviewer/9U37U8CLSQYPTXWBENL3/

Mobilehomer Posted at 4-12 17:40
Also no mention of home point being set.

From the log file:
0m 23.8s        P-GPS        8satellites        9.2ft        10.8ft        2.7mph        2.3ft        59%        13.993V        3.52V        3.50V        3.48V        3.51V        0.039V        Home Point Recorded. RTH Altitude:  30m.

This was after liftoff so is that a reason for this, that the home point was not recorded while still on the ground?

Log file: https://www.phantomhelp.com/logviewer/9U37U8CLSQYPTXWBENL3/

Hello there patrick. I am sorry to read and to know what happened to your DJI Mavic 2 Pro and thank you for reaching out. Since this unfortunate event happened to your DJI Mavic 2 Pro, I would recommend for you to contact our DJI Support Team at https://www.dji.com/support?site=brandsite&from=nav for further assistance with regards to this matter. We will do there best to help you and give out the best resolution for the said issue. Again, I am sorry and thank you.

patrick@patrickbennett.com Posted at 4-12 20:08
From the log file:
0m 23.8s        P-GPS        8satellites        9.2ft        10.8ft        2.7mph        2.3ft        59%        13.993V        3.52V        3.50V        3.48V        3.51V        0.039V        Home Point Recorded. RTH Altitude:  30m.

Hi Patrick

About the HP setting ;

Flight started without a GPS lock.

• 7 satelites but bad on reception, so no GPS lock and ofcourse no HP set.
• Manual takeoff, your Mavic2 stable because of the vision active.
• Flying in OPTI mode away from your start point, at 17s 8 sats and better reception ; so now in GPS mode
• But still no HP set, as the GPS reception is not that good
• At 23s HPS is set, so HP not set at your starting point!
• At 33s countdown for autolanding ; flying  in a resticted zone.
  

See your flight summary in my chart.

Flying away from start point without a GPS lock and not wait for HP to be set is not wise thing to do.

At 15s in flight the warning "Weak GPS signal. Positional accuracy may be compromised. Please fly with caution" At this time receiving 8 satelites with a low GPS 'health' ; changing mode from OPTI to GPS mode but position recordings can be bit incorrect.

And, when having a GPS lock at start, your drone knows if it is in a no fly zone, if outside that it is not possible to fly into a no fly zone.
Flying without GPS into a restricted zone and GPS is kicked in than, as you know, it does an autoland.


See the GE map ; shows where the HP was set. flight line starts where the GPS LatLon was recorded.
cheers
JJB

patrick@patrickbennett.com Posted at 4-12 19:51
This message after takeoff is why I though GPS location is approximate (in the log file): Weak GPS signal. Positional accuracy may be compromised. Please fly with caution.

Log appears to have GPS throughout flight.

This message after takeoff is why I though GPS location is approximate (in the log file): Weak GPS signal. Positional accuracy may be compromised.
Weak GPS signal, is DJI's clumsy way of saying that you don't have GPS at all.

Log appears to have GPS throughout flight.
Think again.
In your flight data, the columns for latitude/longitude are blank for the first 17.9 seconds.
The drone started to get GPS data at 18 seconds, but the flight controller wasn't satisfied with the quality of the location data until 23.4 seconds and it recorded a home point at 23.8 seconds.
You had been flying forward since 11.1 seconds, but we can't tell how far you flew because there was no GPS data.
The autolanding warning appeared at 34.3 seconds and after that it was game over.

If you had waited for GPS and for the home point to be recorded, the drone would have known where it was.
If it was inside the NFZ, it would have refused to launch.
If you launched outside you could fly towards the NFZ, but it would have been like hitting a soft, invisible wall.
You could have flown along or up and down the wall, but not through it.

With the Mavic 2, you need to wait until the app tells you that it has acquired GPS and recorded a homepoint.
You see the top of your screen turns green with this message when this happens and you hear the lady telling you that the homepoint has been recorded.

Labroides Posted at 4-13 02:21
This message after takeoff is why I though GPS location is approximate (in the log file): Weak GPS signal. Positional accuracy may be compromised.
Weak GPS signal, is DJI's clumsy way of saying that you don't have GPS at all.

Great information a couple days late. Thanks so much for explaining this, I wasn't in any hurry to take off and just never had this happen before, a perfect storm of mistakes.

It was only about 10 meters away from the takeoff point but that was enough to put it out over the water, and your interpretation of the data explains why I couldn't bring it back with the controller. I'm guessing my canceling the return to home didn't change the fact that it thought home was where it was, not the actual takeoff point. I won't forget this lesson.

JJB* Posted at 4-12 22:50
Hi Patrick

About the HP setting ;

Great info, thanks for explaining in such detail. I can see I had a perfect storm of mistakes, lesson learned.

fans7807bce2 Posted at 4-13 10:20
Great info, thanks for explaining in such detail. I can see I had a perfect storm of mistakes, lesson learned.

Hi,

My pleasure to help.

During autoland your drone followed the few RC commands, only not the UP stick.
Guess you had too little time and height to yaw the craft and fly towards dry feet area....

cheers
JJB

fans7807bce2 Posted at 4-13 10:17
Great information a couple days late. Thanks so much for explaining this, I wasn't in any hurry to take off and just never had this happen before, a perfect storm of mistakes.  
It was only about 10 meters away from the takeoff point but that was enough to put it out over the water, and your interpretation of the data explains why I couldn't bring it back with the controller. I'm guessing my canceling the return to home didn't change the fact that it thought home was where it was, not the actual takeoff point. I won't forget this lesson.

I'm guessing my canceling the return to home didn't change the fact that it thought home was where it was, not the actual takeoff point.
2 points ..
The drone was never in RTH for RTH to be cancelled
When landing, the drone knew it was 20 metres from home (where it recorded a home point).

DJI's NFZ mapping shows that where you launched was inside the NFZ and launching would have been prevented if you had waited for GPS.
There is a large NFZ that extends out to the international border to prevent overflying of submarines and other warships.


Another point ... your battery had fallen to very low voltage within a minute of launching.
The battery had been discharging for some time and the % indicator is not accurate unless you start with a full battery.

Labroides Posted at 4-13 13:51
I'm guessing my canceling the return to home didn't change the fact that it thought home was where it was, not the actual takeoff point.
2 points ..
The drone was never in RTH for RTH to be cancelled

Hi Labroides,

Read your text about his batt values, to me looks like normal values, mayby bit lower than 'normal'.
Starting a flight with 60% does not mean that the % indicator is not accurate.
If i start a flight with 100% batt, land at 60%, start next flight with 59%....% indicator is accurate.
When i start this next flight few hours after the first 100-60% flight, still good % accurancy.

See Mavic2 batt values [ range 84-21% ] from a random picked Mavic2 drone and Patricks drone.
Mayby just a little lower cell values but not "verly low" i would say.

Do you know why thi UP command had no effect on this drone? i mean, with a critical low battery landing it is still possible to keep it in the air pushing the UP stick.
Mayby UP command not possible when in an autolanding due to NFZ ??  

cheers
JJB

JJB* Posted at 4-13 23:23
Hi Labroides,

Read your text about his batt values, to me looks like normal values, mayby bit lower than 'normal'.

Read your text about his batt values, to me looks like normal values, mayby bit lower than 'normal'.
The battery cell voltages were down to 3.4V towards the end of the flight and the drone was descending slowly, so not under any heavy load.
I just checked cell voltages from a flight I did yesterday with a fully charged battery.
After 14 minutes of mostly hard flying in a 16 knot wind, the battery indicator showed 23% and cell voltages were still at 3.6V.

Labroides Posted at 4-14 05:13
Read your text about his batt values, to me looks like normal values, mayby bit lower than 'normal'.
The battery cell voltages were down to 3.4V towards the end of the flight and the drone was descending slowly, so not under any heavy load.
I just checked cell voltages from a flight I did yesterday with a fully charged battery.

Oke, guess i use an other definition of "very low voltage", for me values below 3.0 volts = very low.

Your flight with 3.6 volts at 23% is the roughly the same as my random picked M2 battery.
Indeed a high power demand your flight ; 23% after 14 minutes.

cheers
JJB

JJB* Posted at 4-14 05:59
Oke, guess i use an other definition of "very low voltage", for me values below 3.0 volts = very low.

Your flight with 3.6 volts at 23% is the roughly the same as my random picked M2 battery.

Oke, guess i use an other definition of "very low voltage", for me values below 3.0 volts = very low.
The critical low voltage level is 3.2 volts.
3 Volts is lower than low.

Labroides Posted at 4-14 06:06
Oke, guess i use an other definition of "very low voltage", for me values below 3.0 volts = very low.
The critical low voltage level is 3.2 volts.
3 Volts is lower than low.

Thanks both of you for really explaining this, very helpful for the future. Once I replace said drone of course.