Flying over water

[Smokey5159]

Hi guys,
I know this topic has been bandied around a little, but I am out camping near a lake, and I want to report my experience. This morning I rose at sunrise to fly and record, and the water was smooth and flat with some dead trees dotted around - the making of a great scene. I took off (to over 10 metres to get home point) with everything normal and then descended to about 3 feet before venturing to the lakes edge. The MP went fine for a few feet but then rose abruptly by itself as if had sensed something under it.
Is this a case of the water causing confusion to the sensors? Would you recommend disabling OA whist doing this kind of filming?

 

[Parman]

It's a known issue that water confuses the sensors. Disable them and you should be fine.

 

[YngveN]

I would say yes and yes.

 

[bravo kilo]

Maybe it did sense something. Are there any lake monsters in your area?

 

[Smokey5159]

Thanks guys - thought so, but just wanted clarification. [emoji106]

 

[Drone Master]

As Parman said, there are known issues. Most report that the Mavic descends and can drop right into the drink. You absolutely want to disable VPS when flying low over water. Turn on again for assistant landing if need be.

 

[Smokey5159]

No monsters that I know of - though the fish have been jumping so I'd better beware! [emoji16] No Obstacle Avoidance for me then!

 

[BorisTheSpider]

It's not forward OA you want to disable, it's the downward facing visual positioning sensors

 

[boone]

I dont even know that I’d call it an “issue”. There are sensors that face downward. Water reflects. Even if it isn’t reflecting and there are waves, the sensors pick up a change in the elevation of what they’re seeing below. Not even sure how DJI would go about “fixing” that or if I’d even want them to.

As a result of the location I live in, I fly over water nearly exclusively. If I’m going to fly low (below ten feet like you were doing) I turn off the downward facing sensors. If you fly above fifteen feet, though, they are not going to be enabled anyway, so no need. What you experienced is “normal” compared to my own personal experiences. And from everything I’ve read and learned, nothing is actually “going wrong” here. Just my own opinion.

 

[Spanishcop]

Screen shot of where to disable this sensor?

 

[boone]

Here you go

 

[Spanishcop]

Thanks. I will use that option. I was recording some waterfalls and was having similar issues described.

Thank you

 

[boone]

Thanks. I will use that option. I was recording some waterfalls and was having similar issues described.

Thank you

Just learn where it is in the UI and get comfortable switching it on and off. You’ll want to enable it again when you’re done with the low flight. Or at least, I prefer to do it that way.

 

[boone]

Thanks. I will use that option. I was recording some waterfalls and was having similar issues described.

Thank you

Woah, also just realized you said “waterfalls”. Be careful. There is at least one video I’ve seen of a mavic taking a nose dive into the water around the base of a short waterfall.

 

[Smokey5159]

Oh yeah - thanks for steering me right. I'm mixing my terms....
Downward sensors are not the same as forward vision sensors - my bad!!!

 

[ablack]

I dont even know that I’d call it an “issue”. There are sensors that face downward. Water reflects. Even if it isn’t reflecting and there are waves, the sensors pick up a change in the elevation of what they’re seeing below. Not even sure how DJI would go about “fixing” that or if I’d even want them to.

As a result of the location I live in, I fly over water nearly exclusively. If I’m going to fly low (below ten feet like you were doing) I turn off the downward facing sensors. If you fly above fifteen feet, though, they are not going to be enabled anyway, so no need. What you experienced is “normal” compared to my own personal experiences. And from everything I’ve read and learned, nothing is actually “going wrong” here. Just my own opinion.

Are you saying that even with excellent GPS signal the VPS will also be used when flying low? I thought VPS was only used for indoor flying in OPTI mode or for precision landing.

 

[mildim]

As far as i know , Downward VPS is used all the time if activated.

 

[Spanishcop]

Are you saying that even with excellent GPS signal the VPS will also be used when flying low? I thought VPS was only used for indoor flying in OPTI mode or for precision landing.

I do know it uses vps in low flight. I've tried to fly low and it would stop at a given distance not let me go lower than about 3 or 4. Trying to lower would cause landing

 

[1-2-hak]

I have also experienced the climb over rapids and waterfalls. Freaked me out for a minute and if you push down too much when it does it it could force autoland. That would be a very bad thing on v01.03.0500.
Turn off if over water!

 

[Mavicsailor]

Hi guys,
I know this topic has been bandied around a little, but I am out camping near a lake, and I want to report my experience. This morning I rose at sunrise to fly and record, and the water was smooth and flat with some dead trees dotted around - the making of a great scene. I took off (to over 10 metres to get home point) with everything normal and then descended to about 3 feet before venturing to the lakes edge. The MP went fine for a few feet but then rose abruptly by itself as if had sensed something under it.
Is this a case of the water causing confusion to the sensors? Would you recommend disabling OA whist doing this kind of filming?

You state you were flying around sunrise. The Mavic could have falsely sensed the sun low on the horizon as an obstacle using the forward OA sensors, where it may have attempted to climb over it. It's a known Issue. Turn off OA, or quickly flip into sports mode which does the same thing.

There is also an issue using where using full down throttle in some situations, where the downward sensors are tricked into an autoland, even at high altitudes. With the latest FW this can't be canceled using throttle up, and the AC could continue descend into the water. Workaround on this is to flip between gps and fast mode using the slide switch (or reverse), or better yet, just turn off landing protection. (Thanks BudWalker). With landing protection off it won't stop at .5 meters and will wait for landing confirmation, but you will have full control all the way to landing. Even with full downward throttle, it will slow to a soft landing.