Do I need to turn off downward VPS flying over water?

[niclariv]

I see in some old (pre-Mavic) posts online that you should turn off downward VPS when flying over water, but the Mavic manual doesn't mention it. I've seen a couple of videos now where people had their Mavic quite low over water - even in the ad video DJI made for Mavic it ends with it hovering quite low over water.

Those people who flew low over water, did you disable VPS?


iPhone 6S

 

[f3honda4me]

I would not turn it off, I know of no reason to turn it off flying over water.

 

[john94si]

What does VPS stand for?

 

[f3honda4me]

vision positioning system

 

[niclariv]

I would not turn it off, I know of no reason to turn it off flying over water.

Older posts (related to phantoms) recommend to turn it off because the drone can get disoriented by the moving surface of the water.


iPhone 6S

 

[Logger]

Page 25 of the Mavic manual...
"Forward and Downward Vision Systems may not function properly when the aircraft is flying over water"

I take this to mean it is not saying turn it off. Just that it may not work and not to rely on it.

 

[niclariv]

That's what I figured but I thought I'd ask if anyone has had any bad experiences leaving it on while flying low over water


iPhone 6S

 

[Logger]

Altitude is governed by pressure sensors (barometric altimeter) so flying over water will not be effected directly. However Terrain avoidance using the ultrasonic sensors below 45' or whatever the height is, will probably not protect you if you blindly descend like you can over land. So my technique has been to carefully set the height over water I want and then to fly level not descending. Further if you were to lose GPS or end up in ATTI mode and try to hover over water it will most likely drift. The visual position sensing may well have difficulty sensing drift over water.

 

[Andrew F]

Altitude is governed by pressure sensors (barometric altimeter) so flying over water will not be effected directly. However Terrain avoidance using the ultrasonic sensors below 45' or whatever the height is, will probably not protect you if you blindly descend like you can over land. So my technique has been to carefully set the height over water I want and then to fly level not descending. Further if you were to lose GPS or end up in ATTI mode and try to hover over water it will most likely drift. The visual position sensing may well have difficulty sensing drift over water.

Visual positioning system will absolutely not work over water.

 

[Logger]

Visual positioning system will absolutely not work over water.

I beg to differ. It MAY work over a shallow kiddies pool with a distinct and clear pattern visible through the water. Or over any very shallow body of calm water with a clear pattern visible beneath. As long as the pattern is constant and clearly visible. OTOH over a featureless body of water or one that is motion, No of course it will not work.
I see the lack of vertical height sensing as a bigger issue above water. If you carelessly descend the unltrasonic sensors will probably not detect the water to avoid a collision.
Not game to test this though.

 

[Andrew F]

I beg to differ. It MAY work over a shallow kiddies pool with a distinct and clear pattern visible through the water. As long as the pattern is constant and clearly visible. OTOH over a featureless body of water or one that is motion, No of course it will not work.

Are you being serious? If so, Hahaha Haha. If not, haha haha. Clearly we were talking about water as in lake, river, ocean, etc. You are correct. For all those flying over kiddie pools with pictures on their floors, and no wind or sun glare, it will likely work.

 

[Logger]

There are very few absolutes in this world ;-)

Visual positioning system May not work over water.

 

[Andrew F]

There are very few absolutes in this world ;-)

Visual positioning system May not work over water.

Haha. You actually got me. There mostly are no absolutes. Saying "there are no absolutes" is clearly oxymoronic. )

 

[MavicPilotTS]

Thank you guys you made me confident again for flying over water.

Back here in Switzerland we have a lot of lakes with mountains around it and that's perfect for filming. But with those old Phantom posts it made me really nervous but now because of you, thank you, I will fly over the lake completely relaxed.

I'll just leave VPS on because Mavic is going to stabilize itself to GPS / GLONASS primarily when in GPS Mode right? And I guess then just fly like you would on land. Not to low... better some clearance

 

[Gary cato]

ok so there are people with Mavics who have already posted about this. When flying above 5 meters the drone would fly fine but in hover at less than 5 meters the drone would descend slowly towards the water. In each case i read on here the pilot caught the drift before it managed to turn the Mavic into a duck,. It was recommended that in hover, the downward sensors are turned off if you are flying very very close to the surface.

edited to add in the same way the sun can cause the mavic to go into obstacle detection when flying into the sun. the sensors are not foolproof.

 

[Robbyg]

Turn off VPS when flying over large bodies of water. And then turn it back on when your getting ready to land.

There seems to be enough evidence to suggest that the Mavic during hovering over water will often be fooled and start to depend on false info from the VPS. The craft will think it is at a level height when in fact it is descending lower and lower towards the water. Not enough is known on why this happens, but enough cases have happened to make it prudent for people to turn off the VPS.
This does not apply if your flying 60ft above the water and out of the VPS range.

Rob

 

[mlaczek]

Haha. You actually got me. There mostly are no absolutes. Saying "there are no absolutes" is clearly oxymoronic. )

piggy nose smile [emoji1]

 

[Blucenturion]

Turn off VPS when flying over large bodies of water. And then turn it back on when your getting ready to land.

There seems to be enough evidence to suggest that the Mavic during hovering over water will often be fooled and start to depend on false info from the VPS. The craft will think it is at a level height when in fact it is descending lower and lower towards the water. Not enough is known on why this happens, but enough cases have happened to make it prudent for people to turn off the VPS.
This does not apply if your flying 60ft above the water and out of the VPS range.

Rob

Great post, Rob.

 

[mlaczek]

Turn off VPS when flying over large bodies of water. And then turn it back on when your getting ready to land.

There seems to be enough evidence to suggest that the Mavic during hovering over water will often be fooled and start to depend on false info from the VPS. The craft will think it is at a level height when in fact it is descending lower and lower towards the water. Not enough is known on why this happens, but enough cases have happened to make it prudent for people to turn off the VPS.
This does not apply if your flying 60ft above the water and out of the VPS range.

Rob

thank you for this info!

what do you think Rob, the VPS just above the cristal clear water doing wrong metering, or above the dirty water too?

 

[Robbyg]

thank you for this info!

what do you think Rob, the VPS just above the cristal clear water doing wrong metering, or above the dirty water too?

Honestly there is not enough data to make that call.

Rob