flying over water

[Meta4]

I gave second thought to the issue, trying to analyze system response, so we have GPS altitude measurement and the sensors facing down. I think we can safely assume that those measure actual distance from the water surface reflection as well as the bottom below and safety system get "confused". So if my theory is right this wavering is more pronounced lower the drone fly towards the surface and depends of actual depth and translucency of the water

Two points to factor into your thinking:
1. The drone only uses GPS for horizontal position data. It uses a barometric sensor to measure altitude.
2. The VPS is a combination of visual and ultrasonic sensors.

 

[beach_Dr]

I only turn off forward sensors when flying over water, no obstacles out there, wont get confused with the sun, and can fly a lot faster without having to engage sport mode.

I've never had problems with downwards sensors. I can imagine landing protection will only cause a problem if you are descending and VPS thinks you are lower than you are, so starts a landing procedure.

I fly mainly over ocean though, not much experience flying over still clear waters.

 

[Rusty in Bend]

Actually the river could have messed with VPS if it was low enough. It nearly happened to me.

One thing I learned recently that I hadn't realized is that the distance above the ground is measured at takeoff, and I don't believe it updates. That means as you fly "up-river", your elevation will increase, your altitude will decrease, and eventually, you will ... (blub blub blub)

 

[Meta4]

One thing I learned recently that I hadn't realized is that the distance above the ground is measured at takeoff, and I don't believe it updates.

All heights shown are relative to the launch point.
It that what you're trying to say?

 

[Mike_Flys]

Mavic Pro/Platinum use a sonic sensor to help with low altitude flight.
Mavic 2s use an infrared sensor instead of the sonic sensors.
My testing shows the Mavic 2 has a harder time holding altitude when close to the water than the Mavic Pro.

Here is a video of a low altitude hover test over water sensors on with the Mavic 2. at one point it goes from 3 feet to nearly 10 feet and the controller still says 3ft.
It does seem to drift more.

 

[Meta4]

Mavic Pro/Platinum use a sonic sensor to help with low altitude flight.
Mavic 2s use an infrared sensor instead of the sonic sensors.

The original Mavic has visual and ultrasonic downward facing sensors.

My testing shows the Mavic 2 has a harder time holding altitude when close to the water than the Mavic Pro.

The manuals warn you that the downward sensors can have trouble if flying close to the water's surface.

 

[Mike_Flys]

The original Mavic has visual and ultrasonic downward facing sensors.
The manuals warn you that the downward sensors can have trouble if flying close to the water's surface.

Both the Mavic Pro and the Mavic 2 have visual sensors on the bottom. They help with positioning at low altitudes and indoors.

Yes the manual does and so does the DJI website. DJI recommends turning off the Vision Positioning sensors (bottom sensors) for flying over water. I explained all this in a Facebook group & youtube channel, but for whatever reasons people like to know what happens. So since I have the ability to land on water, which means I can safely fly low over the water I did a low altitude hover video for the groups youtube channel.

I have hundreds of water landings/take offs on Mavic drones, and two successful water crash recovery's. over the past couple of years.

 

[Huge Bama Fan]

I fly over rivers and Waterfalls a lot. As mentioned above the sensors can get confused. Cut them off if you are flying low over rough water. Also be mindful and have a plan if things go wrong.