MM gains altitude over water?

[Sprucegoose]

So I was flying and doing some filming Sunday with my son and had an interesting experience. I was shooting some footage through some pretty open wooded trails along the river here in FL. And decided to take the mini through a large opening and out over the water only about 30 feet out and only at an altitude of about 7 feet to shoot back at us and everything was fine but as I was turning back to come in the mini was slowly gaining altitude all on its own with no input. I was in C mode and had to add quite a bit of down stick to keep it from rising into the overhanging limbs and get it back safely. If I went hands off to hover it would go up.
had no other issues the whole day, any way taking it over the water could have any cause in this? Low wind day and was high enough I think to be out of any wash but?
That was enough to shake me a bit as a new pilot so thought I would just ask.

 

[Fadly]

Mine slowly loosing altitude instead. I think the choppy water may have confuse the bottom sensor.

 

[blakamin]

Page 16 of the manual...

"The Vision System works best between 0.5 and 10m..."
"the Vision System cannot work properly...
c. Flying over water or transparent surfaces"

https://dl.djicdn.com/downloads/Mavic_Mini/Mavic_Mini_User_Manual_v1.0_en_0.pdf

 

[Matto1981]

I was flying over a pond today, 10-15 feet above the water and the Mini had no altitude changes.

 

[Sprucegoose]

Page 16 of the manual...

"The Vision System works best between 0.5 and 10m..."
"the Vision System cannot work properly...
c. Flying over water or transparent surfaces"

https://dl.djicdn.com/downloads/Mavic_Mini/Mavic_Mini_User_Manual_v1.0_en_0.pdf

Interesting, our water is far from transparent and I instinctively would understand it having a loss of altitude over clear water if the drone couldn’t differentiate the top of the water VS the solid bottom but gaining altitude? Maybe a reflection issue? it was rather calm. The St. John’s river is brackish and quite dark brown.

 

[Fadly]

I wonder what's that smaller circle in between the two Vision System cameras under the MM? Is it a laser?

 

[blakamin]

Maybe a reflection issue? it was rather calm.

Read the rest of page 16... There's a whole list of things.
I'm not typing it out for you!

 

[TDZHDTV]

Was you flying into the wind? The MM gains height when flying against the wind, it does it in all modes, it’s more pronounced in S mode.

 

[old man mavic]

in the manual as stated above it lists all the conditions where the downward vision system can be fooled yes fooled, if you look at the size of the sensors then it is amazing that they work as well as the do,but they rely on what the surface you are flying over ,and that can give them a false perception of what it is and the drone will react to that perception

 

[chriscuk]

/\ and I'd rather the drone gains altitude a bit when it's not sure rather than dropping!

 

[Shaw10]

Had the same issue flying over a river that had rapid flowing areas. The rapid spots confused the sensors. Fly above 20ft over water, especially fast flowing.

 

[russellg]

Read pages 15 and 16 of the user manual, using the Downward Vision System.

 

[pmshop]

Flying over water with VPS you need to be prepared for the VPS drop.
You got lucky and it rose.
I am so glad I heard about this before I attempted with a Spark and Mavic Air.
Sure enough, my Spark headed for the water but I was ready.

 

[Sprucegoose]

Read the rest of page 16... There's a whole list of things.
I'm not typing it out for you!

Oh come on...Cut- copy - paste! No need to type it out! J/k
I did, read the whole list before posting, and I can understand why many outdoor settings may be less than ideal for the sensors but that list reads more like a CYA and can apply to a host of situations that are not 100% ideal for flight that one may find themselves in or that may cause some sensor issues I was just hoping for more experience type situations (which I appreciate those that have shared them) from members than I was a reference to the manual. Sorry if that point was missed in the original post.
I will certainly use caution with lower than suggested altitude over water!

 

[Sprucegoose]

Flying over water with VPS you need to be prepared for the VPS drop.
You got lucky and it rose.
I am so glad I heard about this before I attempted with a Spark and Mavic Air.
Sure enough, my Spark headed for the water but I was ready.

Yeah, I am certainly ok with the rise in altitude in retrospect. Thanks for sharing that.

 

[Sprucegoose]

Read pages 15 and 16 of the user manual, using the Downward

Had the same issue flying over a river that had rapid flowing areas. The rapid spots confused the sensors. Fly above 20ft over water, especially fast flowing.

Thank you, yeah it looks like the height was a determining factor here, if it happens again I will try a rise in altitude to see if it corrects.

 

[Sprucegoose]

Was you flying into the wind? The MM gains height when flying against the wind, it does it in all modes, it’s more pronounced in S mode.

It was rather calm coming back would have been with the breeze.

 

[Sprucegoose]

Page 16 of the manual...

"The Vision System works best between 0.5 and 10m..."
"the Vision System cannot work properly...
c. Flying over water or transparent surfaces"

https://dl.djicdn.com/downloads/Mavic_Mini/Mavic_Mini_User_Manual_v1.0_en_0.pdf

Yeah, I think height was the determining factor.

 

[netsonic]

I wonder what's that smaller circle in between the two Vision System cameras under the MM? Is it a laser?

This is a pinhole video camera used for downward looking and pattern recognition. This is the same technology also used in other drones. The camera looks down and is used for stability (keep the mini hoovering) without drifting front-back or sideways.

The two vision cameras you've mentioned are in fact just LED's used to transmit and receive light.

 

[chriscuk]

Today was my first time of seeing how much height it gains when in the wind.

I took it to the beach and was about 15m up, every few moments it'd visivibly shoot up maybe 2-3m then all of a sudden it just climbed 10-15m which was very obvious as it was very close to me at the time.

Honestly thought I had a fly away!