When flying over tyhe sea with my Air 2s, I experienced a strange behavoir related to the altitude control. First of all, the sonar altitude stopped working at about 5m altitude (usually it works until 25m). And at certain point, the drone started gently climbing without any input. Here the log:
https://www.phantomhelp.com/LogViewer/0YQMXURHWDDLWKC8H900
  

As you can see, from 2:56 and 3:05 the climbed from 8.2ft to 23.3ft without any input.

In the video I took:   this corresponds to 0:30 to 0:38 and it seems that the altitude is unstable, moving slightly up an down.

At the end of the flight, the precision landing was not accurate: about 30cm form the real home point (usually it lands at no more than 5-10 cm).

I've a limited experience with the Air 2s and I'd like to know if this behavior is int the acceptable range or I should send it back for a check.

Thanks

Hello there FabioV. I am sorry for the trouble this has caused and thank you for giving out these information. Just a friendly reminder that when flying above water, the vision positioning function will turn off automatically and only the GPS and barometer are used for positioning, if affected by the accuracy range, and an accident might happen. In addition I will also post a DJI Forum thread on How to Fly Safely Over Water. Thank you and fly safe always.

https://forum.dji.com/forum.php?mod=viewthread&tid=181878

DJI Stephen Posted at 10-11 00:48
Hello there FabioV. I am sorry for the trouble this has caused and thank you for giving out these information. Just a friendly reminder that when flying above water, the vision positioning function will turn off automatically and only the GPS and barometer are used for positioning, if affected by the accuracy range, and an accident might happen. In addition I will also post a DJI Forum thread on How to Fly Safely Over Water. Thank you and fly safe always.

https://forum.dji.com/forum.php?mod=viewthread&tid=181878

Thanks for replying to my post. If I'm correctly understanding, the behaviour of my Air 2s was normal, because the VPS is automatically disabled. In the post you linked, the automatic VPS disabling is not mentioned, but I assume that the post is quite outdated and related to older models.
I was aware about the risks of flying over the water and I always kept an altitude over 2m. Then the unstable height did not put at risk my Air 2s, only the quality of my videos.

DJI Stephen Posted at 10-11 00:48
Hello there FabioV. I am sorry for the trouble this has caused and thank you for giving out these information. Just a friendly reminder that when flying above water, the vision positioning function will turn off automatically and only the GPS and barometer are used for positioning, if affected by the accuracy range, and an accident might happen. In addition I will also post a DJI Forum thread on How to Fly Safely Over Water. Thank you and fly safe always.

https://forum.dji.com/forum.php?mod=viewthread&tid=181878

Hi Stephen,

And again you post this outdated link!!  why ?

FlyApp drones cannot disable the VPS bottem sensor!!

And the vision positioning is not turned off automatically flying over water!
And what do you mean with "...affected by the accuranct range, an accident might happen" ?? It is so wrong!

I fly many times low over water, VPS bottom sensor does sense alway the correct height.Only when flying slow or hovering low over streaming water the VPS downward sensor gets sometimes "confused"....
Well, just my experience flying many many flights low over water.
And, analyzing logs, you can see that the vision is not used for positioning when the GPS signals are oke. (see the manuals as well ....)

Best for DJI is to change the autolanding protection such that it will automatically turns off with some speed in any direction! This has caused many wet drones....

Cheers
JJB

JJB* Posted at 10-11 01:32
Hi Stephen,

And again you post this outdated link!!  why ?

Hi JJB, any comment about my log ?
Thanks

Hi Fabio,

VPS botten sensor needs good surface below to be able to measure correct distance.

Loosing VPS height is 'normal' when flying low over water, if the suface of the water is real smooth....
Like in your lovely day weather video.

Result of low flying over water and loosing VPS height does have efffect on the flying height.
In you flight happily more Up than Down!
See my chart of your data ; baro height line Yellow = Up, Red = Down (with no RC Up/Dn input ofcoursse)

About the landing precision. After takeoff at 5.4s HP was updated again ; 50 cm away from the first HP.
So your 30cm was mayby just 20 cm....nice performance i think !


BTW steady low flying over water is possible, even with smooth water, just keep the speed down! with higher speed the VPS height sensor will loose its measurement....In the video VPS height = 1 meter.



cheers
JJB

DJI Stephen Posted at 10-11 00:48
Hello there FabioV. I am sorry for the trouble this has caused and thank you for giving out these information. Just a friendly reminder that when flying above water, the vision positioning function will turn off automatically and only the GPS and barometer are used for positioning, if affected by the accuracy range, and an accident might happen. In addition I will also post a DJI Forum thread on How to Fly Safely Over Water. Thank you and fly safe always.

https://forum.dji.com/forum.php?mod=viewthread&tid=181878

Just a friendly reminder that when flying above water, the vision positioning function will turn off automatically and only the GPS and barometer are used for positioning,
How many times are you going to repost this misinformation?
Do you even notice every time that JJB and I tell you it's completely untrue?

JJB* Posted at 10-11 01:51
Hi Fabio,

VPS botten sensor needs good surface below to be able to measure correct distance.

Thank you very much for your analysis. It confirms that the Air 2s is working as expected and it does not need any further investigation. My only concerns is that I would expect more accurate answers from the DJI support: posting outdated (and not true) information is not professional at all.