I do not want to create alarmism but it is right that the circumstance is taken into account both by the MAVIC 2 pilots and by DJI whom I am forwarding this message to.

I'll tell you what happened to me with two mavic Zoom (but I read in the network of other cases similar to mine)

In early October, purchase the Mavic 2 Zoom from a well-known shop.

I update drone and remote controller to the most recent version of that time, v. 1,000,000 and installed the latest DJI GO V4 application for Android (v. 4.3.2.) on my XIAOMI MI PAD 4 LTE 4gb / 64gb

I turn on the AIRCRAFT and RC, made the pre-check list (RTH at 50 meters, RTH in case of loss of signal, battery status and cells etc. etc.) and after hooking 18 satellites start flying without any anomaly.

At a certain distance from me (but no long range), I lose the signal between Radio and Drone and on the display of the radio control, the word "Connecting" appears to me.

After a few seconds, seeing that nothing happens, I start to move and hang up the connection. The Mavic had stood still in the air for a good 40 seconds. It never started the Return To Home. Obviously the application was (as always) configured to return to the take-off point and not hovering.

I landed the drone, immediately I go to analyze the flight data and I am disconcerted, since having seen that the Mavic 2, without any connection with radio control, has NOT STARTED the RTH. It was me, as soon as the connection was reestablished, to activate the RTH.

Since the drone was less than 6 days from the purchase, I went to the dealer who replaced it with another sealed one.

I take the new drone, I upgrade to the FW 1,000,000 and yesterday, with a day without the sun, I finally managed to fly.

All apparently working, apart from an error message VPS Obstacle avoidance sensors errors, immediately gone ... however I was flying in P mode (as always) and without any other automation.

Taken up a lot of courage (mindful of the previous experience), I bring the drone in an uninhabited area, about 35 meters away from me and about 40 meters high and I decide to test the FAILSAFE of Mavic 2 for loss of signal, so I turn off the radio control: in this case, like all drones, the Mavic 2 would have to return to the starting point: but in reality it was not. At first the Mavic 2 turned towards my direction and started to approach the take-off point (and so far everything is ok); then suddenly it stopped, turned around 15 ° and moved from a take-off point; then it turned again and started to rise rapidly. At that point I immediately switched on the remote controller and gained control over the drone: As soon as the connection appeared on the display appeared the word gohome and then also on the tablet, with 19 hooked satellites that I had left shortly before, at take-off. On the display map the H was correctly shown and placed; in all this few time the drone had already reached the height of 125 meters, although I had set the RTH to 50 meters (I also checked after landing and the set value was always 50 meters). There was no sun and therefore no interference with the sensors.

I can understand that at most it may seem that I have made a madness (and maybe it was) but according to me, in a drone the first thing that must work, without any doubt, it is the FAILSAFE RTH.

That is, if I was flying a little more distant (but respecting the limits) and suddenly for any reason, if the connection between drone and radio control had been lost, what would have happened?

After what has happened to me, of course, I will not be able to fly calmly.

At this point, it would be advisable to verify that this is a (serious) bug in the firmware or software and especially to bring it to the attention of DJI so that, if confirmed that it is a bug, fix it.

Nicely done - thanks again for sharing.

So far I haven't had this issues with my Mavic 2 thankfully.  I've had 2 incidents where I lost all connection even with the controller and it did it's normal RTH but I got control prior to it actually landing and manually landed it.  Both times where from me flying near the cemetery by my house which happens to have a massive Cell tower right there which I assume is the cause of my disconnects. Never had it happen anywhere else.

Hi Lukappaseidue. Thank you for sharing this information to us. To have a safe flight please try to have a pre flight checklist by checking the drone itself and the environment where you are going to fly the drone. Make sure that if you will fly the drone check if you have enough satellites, make sure to record the home point and check the surroundings if there are structures that can cause interference the signal from your remote controller to the aircraft. Have a safe and happy flying.

Hiya,

What a story to tell us....is it possible to upload your flightrecords ? before and after the RC connecting.

cheers
JJB

DJI Stephen Posted at 11-1 10:27
Hi Lukappaseidue. Thank you for sharing this information to us. To have a safe flight please try to have a pre flight checklist by checking the drone itself and the environment where you are going to fly the drone. Make sure that if you will fly the drone check if you have enough satellites, make sure to record the home point and check the surroundings if there are structures that can cause interference the signal from your remote controller to the aircraft. Have a safe and happy flying.

Thank you very much for your reply,
I am not novice: Every time i fly I always pre flight check list:
I fly always with more than 14 satellites
checking RTH height
drone behaviour in case of lost signal
the "H" home point is well recorded and no interferences near the place
I also check sensors status, health of the battery
The issue occur randomly amd only when the SIGNAL CONTROLL IS LOST, and the only way to check what the drone do in case of signal lost, is switching off the remote controller
Its all.
The strange was that, when switched on the remote controlle, the GOHOME message appeared on remote controller display and device too, and the drone start return home. So only when signal is lost, RTH  is not so safe

JJBspark Posted at 11-1 11:42
Hiya,

What a story to tell us....is it possible to upload your flightrecords ? before and after the RC connecting.

Yes of course, but not in public, I can sent you my airdata CVS files

DJI Stephen Posted at 11-1 10:27
Hi Lukappaseidue. Thank you for sharing this information to us. To have a safe flight please try to have a pre flight checklist by checking the drone itself and the environment where you are going to fly the drone. Make sure that if you will fly the drone check if you have enough satellites, make sure to record the home point and check the surroundings if there are structures that can cause interference the signal from your remote controller to the aircraft. Have a safe and happy flying.

Hi have uploaded Flight log from DJI Assistant and DJI GO V4 too.
Any news, please?
I have fear to fly

I also tested the test, I turned off the controller to verify the fail safe rth ........ fear !! ... my Mavic 2 zoom in more than one occasion went away from a completely different part ...... for me this is a situation of an absurd gravity ..... very very dangerous. I just hope it's a software / firmware problem and not hardware because otherwise it would be unsolvable. I flew with both drone and controller updated to the latest firmware available ...

fansb31b12c6 Posted at 11-4 05:29
I also tested the test, I turned off the controller to verify the fail safe rth ........ fear !! ... my Mavic 2 zoom in more than one occasion went away from a completely different part ...... for me this is a situation of an absurd gravity ..... very very dangerous. I just hope it's a software / firmware problem and not hardware because otherwise it would be unsolvable. I flew with both drone and controller updated to the latest firmware available ...

"my Mavic 2 zoom in more than one occasion went away from a completely different part "

How far did it go before you switched on RC again ?

When the RC is switched off and the aircraft cannot see a signal, then it will retrace the route it has taken to get to that point, in the hope of reconnecting to RC, it will not immediately fly back in a straight line.

So if you fly behind a tall building (higher than RTH height) and loose signal, the aircraft will then retrace its path back the way it came round building to try and reconnect to RC.

fansb31b12c6 Posted at 11-4 05:29
I also tested the test, I turned off the controller to verify the fail safe rth ........ fear !! ... my Mavic 2 zoom in more than one occasion went away from a completely different part ...... for me this is a situation of an absurd gravity ..... very very dangerous. I just hope it's a software / firmware problem and not hardware because otherwise it would be unsolvable. I flew with both drone and controller updated to the latest firmware available ...

When you switched off RC or lost signal, your aircraft will first start to fly the route it has just flown on its RTH , if it regains signal it will stop and hover waiting for controller to take over, failing to take over by controller after 10 seconds aircraft will begin RTH journey with normal straight RTH , I’m afraid Lukaappaseidue version is somewhat lost in translation but I think he may be confused by what he thinks RTH with loss of signal is, but if he has given jjb his log it should be cleared up.
I can tell you haven’t tested RTH in all modes it works correctly and safely.

I also hope that JJB will be able to shade some light on what has actually happened in this case.

Wachtberger Posted at 11-4 09:35
I also hope that JJB will be able to shade some light on what has actually happened in this case.

Yes, i have seen the logs.

1) RTH procedure was OK when the RC was switched off
2) Drone, for some unknown reason, started to climb and climb....far above the RTH height.

Flightlogs were sent to me in private, i will not publish them.

cheers
JJB

hallmark007 Posted at 11-4 07:46
When you switched off RC or lost signal, your aircraft will first start to fly the route it has just flown on its RTH , if it regains signal it will stop and hover waiting for controller to take over, failing to take over by controller after 10 seconds aircraft will begin RTH journey with normal straight RTH , I’m afraid Lukaappaseidue version is somewhat lost in translation but I think he may be confused by what he thinks RTH with loss of signal is, but if he has given jjb his log it should be cleared up.
I can tell you haven’t tested RTH in all modes it works correctly and safely.

Hi Hallmark007, is  it possible that translating what I want to say, I lost somewhat (I apologize)
How do you expect the Return To Home to work? As far as I know, the only way to voluntarily get the Return to Home Falisafe is to turn off the radio control: and I, in fact, turned off the controller. I set the minimum height of the RTH to 50 meters. So I took the drone 40 meters away from me and 40 meters in height, holding it to my sight. The moment I turned off the radio control I would have expected the drone to rotate to the starting point, reach the minimum height set (50 meters) and then return to the take-off point. But this did not happen. the drone first turned towards the take-off point, then began to go towards them, then it suddenly stopped and turned away from the other side and then began to climb up to about 125 meters in height (I I remind you that the height of the RTH was set at 50 meters).
I had to turn on the radio control and at the exact moment when the connection was reestablished, the drone correctly performed the RTH.
Instead, If I hit the RTH button on remote controller or on the display of my device, the RTH is working right.

I hope everything is clearer now.
If anyone else wants to help me, since DJI is not yet answering me, I can share my flight diary.
Thank you all.

Lukappaseidue Posted at 11-4 13:53
Hi Hallmark007, is  it possible that translating what I want to say, I lost somewhat (I apologize)
How do you expect the Return To Home to work? As far as I know, the only way to voluntarily get the Return to Home Falisafe is to turn off the radio control: and I, in fact, turned off the controller. I set the minimum height of the RTH to 50 meters. So I took the drone 40 meters away from me and 40 meters in height, holding it to my sight. The moment I turned off the radio control I would have expected the drone to rotate to the starting point, reach the minimum height set (50 meters) and then return to the take-off point. But this did not happen. the drone first turned towards the take-off point, then began to go towards them, then it suddenly stopped and turned away from the other side and then began to climb up to about 125 meters in height (I I remind you that the height of the RTH was set at 50 meters).
I had to turn on the radio control and at the exact moment when the connection was reestablished, the drone correctly performed the RTH.

I think you might to put up your log, when turning off RC this will cause Aircraft to go into RTH failsafe for loss of signal, this is different RTH than just pressing RTH , and it seems you expected aircraft to proceed the same way.
Loss of signal RTH is different, while you say it climbed to 125 metres, that is different case I can only think of one or instance why it might climb and that is if it was directly flying into the sun.
But there is a difference between normal RTH when implemented by you and loss of signal RTH .

hallmark007 Posted at 11-4 14:07
I think you might to put up your log, when turning off RC this will cause Aircraft to go into RTH failsafe for loss of signal, this is different RTH than just pressing RTH , and it seems you expected aircraft to proceed the same way.
Loss of signal RTH is different, while you say it climbed to 125 metres, that is different case I can only think of one or instance why it might climb and that is if it was directly flying into the sun.
But there is a difference between normal RTH when implemented by you and loss of signal RTH .

Thank you hallmark,
No sun, cloudy day.

here my logs

https://drive.google.com/open?id ... tZfjvHK3ONS6PN-fGuX

JJBspark Posted at 11-4 11:07
Yes, i have seen the logs.

1) RTH procedure was OK when the RC was switched off

"2) Drone, for some unknown reason, started to climb and climb....far above the RTH height."

Does that suggest that there might be a problem with RTH on that unit, or perhaps just a glitch, cause unknown ?

davidmartingraf Posted at 10-29 04:18
Nicely done - thanks again for sharing.

David might be time to quit the ridiculous replies all over the forum, I’m sure your not helping anyone or are you trying to prove a point ?

Lukappaseidue Posted at 11-4 14:23
Thank you hallmark,
No sun, cloudy day.

Had a look at your log it’s unexplained why it climbed so high, maybe you will need to download .dat file ask a moderator here to get engineer to check the .dat file , it’s a pretty big file and you will need to download and put in Dropbox or similar and PM a moderator, I’d suggest dji Mindy or dji Susan , they should be able to get some results privately for you. Sorry I can’t be of more help .

hallmark007 Posted at 11-4 14:56
David might be time to quit the ridiculous replies all over the forum, I’m sure your not helping anyone or are you trying to prove a point ?

I don't think we're always going to provide the best answer or advice here, perhaps there was a question or two where you didn't provide the best answer? I'm only human and make a good faith effort to do my best, that's all one can ask.

Happy flying.

Lukappaseidue Posted at 11-4 13:53
Hi Hallmark007, is  it possible that translating what I want to say, I lost somewhat (I apologize)
How do you expect the Return To Home to work? As far as I know, the only way to voluntarily get the Return to Home Falisafe is to turn off the radio control: and I, in fact, turned off the controller. I set the minimum height of the RTH to 50 meters. So I took the drone 40 meters away from me and 40 meters in height, holding it to my sight. The moment I turned off the radio control I would have expected the drone to rotate to the starting point, reach the minimum height set (50 meters) and then return to the take-off point. But this did not happen. the drone first turned towards the take-off point, then began to go towards them, then it suddenly stopped and turned away from the other side and then began to climb up to about 125 meters in height (I I remind you that the height of the RTH was set at 50 meters).
I had to turn on the radio control and at the exact moment when the connection was reestablished, the drone correctly performed the RTH.

Hi Luka,

The RTH was performed as it should be ; craft retraces its route first and does not fly back to home in a straight line. After some time when no connection it start to turn home and fly home.
See the manual about this.

cheers
JJB

hallmark007 Posted at 11-4 15:51
Had a look at your log it’s unexplained why it climbed so high, maybe you will need to download .dat file ask a moderator here to get engineer to check the .dat file , it’s a pretty big file and you will need to download and put in Dropbox or similar and PM a moderator, I’d suggest dji Mindy or dji Susan , they should be able to get some results privately for you. Sorry I can’t be of more help .

Thank you hallmark, instead you helped me.
You have understood the unexplained behaviour of my mavic 2 zoom.
Now I hope that some DJI moderator read this thread and help me

JJBspark Posted at 11-5 03:10
Hi Luka,

The RTH was performed as it should be ; craft retraces its route first and does not fly back to home in a straight line. After some time when no connection it start to turn home and fly home.

Hi JJBspark, thank you for your reply.
Only 2 things that have to be marked:
1) i set the RTH height to 50 meters and  drone arrived at 125 meters hight, when i switched on the remote controller (perhaps I i swithced some seconds later, it could fly higher and higher)
2) Only when the remote controller was connected, the DRONE start the REAL RTH, but not before.

Lukappaseidue Posted at 11-5 07:22
Hi JJBspark, thank you for your reply.
Only 2 things that have to be marked:
1) i set the RTH height to 50 meters and  drone arrived at 125 meters hight, when i switched on the remote controller (perhaps I i swithced some seconds later, it could fly higher and higher)

Hi Luka,

1) true, drone started to climb and to wich height?? we don`t know that!
2) nope, i think you are wrong. Read and see my charts. Drone did a proper RTH, only not what you expected to happen. Its all in the manual.if you do not have my charts i will upload theme here if you do not mind.

cheers
JJB

Lukappaseidue Posted at 11-5 07:19
Thank you hallmark, instead you helped me.
You have understood the unexplained behaviour of my mavic 2 zoom.
Now I hope that some DJI moderator read this thread and help me

This is the failsafe that might be confusing.

JJBspark Posted at 11-5 07:42
Hi Luka,

1) true, drone started to climb and to wich height?? we don`t know that!

Thank you.
1) this is really strange!
2) The drone has set 50 meters high and not more: there was no sun in front (or back) of the drone, so no sensor issue.  

I have done another test and this last time the drone worked like I expected: When I switched off the remote controller, after few seconds, the drone (far from me 40 meters and at the height of 40 meters) rotate to the home point, than rise to 50 meters high, and than start to fly to home point and then land (This is for me RTH Failsafe)
Anyway, next time, if I ever will test RTH FAilsage, I will wait more than 40 seconds

Lukappaseidue Posted at 11-5 08:22
Thank you.
1) this is really strange!
2) The drone has set 50 meters high and not more: there was no sun in front (or back) of the drone, so no sensor issue.  

1) true really strange, DJI should answer this behaviour.
2) Direct sunlight might effect the (fwd) sensors, obstacle sensing.
I cannot think why sunlight would interfere with a barometric height sensor, only think that mayby the VPS height sensor is affected and when VPS height is indicating this height got higher prio than the baro height. But than that value is written in the file and it was not.

I always fly with a screen recorder active, this way you can re-fly your mission. Beacuse we have only 2 eyes ; hard to watch the screen and watch the drone at the same time.

cheers
JJB