Caution when bottom sensors are off

[Bzzz]

Hi

When flying low over water the bottom sensors should be turned off. My mavic does not maintain altitude otherwise. BUT, that is in the manual. What is not apparent is that when back over land and you land, the feature that hovers 2 ft off the ground prior to touch down is off. This makes it really easy to smack your plane into the ground very hard and very fast. I only did this once but would rather have thought it through in advance

Just fyi for those that have not learned this yet


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[Xcel]

I've smacked it into the ground the same way but with the sensors on. Luckily it wasn't too hard but it was very unexpected.

The reason was I had just flown two batteries when I was asked to do an interview for a local newspaper. In my haste to demonstrate the Mavic to the reporter I put it down on a patch of soft snow before taking off. The snow stuck to the bottom cameras and Ultrasonic sensor. So when I landed a bit later I ended up smacking it lightly into the ground due to the clogged sensors. Luckily there was no damage, apart from to my ego.

Lesson learned always clear the starting area from snow or just take off from my hand.

 

[JLane]

I think DJI should keep the two functions separate. ie. The Visual Positioning System, as the name implies, should only enable/disable the visual sensors used for positional stability. Disabling the VPS should not, in my opinion, also disable the ultrasonic sensors used for measuring ground clearance.

They're actually halfway there, by now allowing us to enable/disable the ultrasonic sensors separately through the Landing Protection option, but they should also unbundle the ultrasonic sensors from the VPS option.

 

[niclariv]

Hi

When flying low over water the bottom sensors should be turned off. My mavic does not maintain altitude otherwise. BUT, that is in the manual. What is not apparent is that when back over land and you land, the feature that hovers 2 ft off the ground prior to touch down is off. This makes it really easy to smack your plane into the ground very hard and very fast. I only did this once but would rather have thought it through in advance

Just fyi for those that have not learned this yet


Sent from my iPhone using MavicPilots

How bad is the altitude variation when flying over water? I've flown over water a bunch of times leaving the sensors on and only once had a problem. It wasn't altitude though, it was drift. I think the sensors saw the movement of the waves below and though it should lock on to them (as in it thought the waves were stationary landmarks). I wasn't low to the water though. I tried a while ago to find out if there's a risk of the drone dropping in to the water if flying low over it and couldn't find any examples of that.. so have you experienced altitude gains and drops over water yourself?


iPhone 6S

 

[Bzzz]

How bad is the altitude variation when flying over water? I've flown over water a bunch of times leaving the sensors on and only once had a problem. It wasn't altitude though, it was drift. I think the sensors saw the movement of the waves below and though it should lock on to them (as in it thought the waves were stationary landmarks). I wasn't low to the water though. I tried a while ago to find out if there's a risk of the drone dropping in to the water if flying low over it and couldn't find any examples of that.. so have you experienced altitude gains and drops over water yourself?


iPhone 6S

It only happens when flying low over water. < 30 ft is what manuals say. I am flying under a lot of bridges, usually 10 - 15 ft. What i see is it starts to sink down slowly loosing its altitude a ft or so every few of seconds. Nothing fast but very unsettling when so low over flowing rivers.




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[JLane]

It only happens when flying low over water. < 30 ft is what manuals say. I am flying under a lot of bridges, usually 10 - 15 ft. What i see is it starts to sink down slowly loosing its altitude a ft or so every few of seconds. Nothing fast but very unsettling when so low over flowing rivers.

And are you sure that vertical drift isn't due to weaker GPS signals while under the bridges? Does turning off the VPS definitely fix the vertical drifting?

EDIT: Or perhaps even a change in air pressure due to fast moving waters and confined spaces under the bridges?

 

[Bzzz]

And are you sure that vertical drift isn't due to weaker GPS signals while under the bridges? Does turning off the VPS definitely fix the vertical drifting?

EDIT: Or perhaps even a change in air pressure due to fast moving waters and confined spaces under the bridges?

Its not gps because both times i noticed well before i put it under bridges. I was over fast moving water so perhaps air. I now turn off sensors and do not notice any drift. When it happened, I remembered manuals warning on it and assumed it was sensors on water. Cannot be definitive.


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[JOHNNYBRAVO]

Okay sorry, why do the senors not detect the water? Is it they see through it to the ground below in shallow water? Sorry I'm a noob.

 

[JLane]

Its not gps because both times i noticed well before i put it under bridges. I was over fast moving water so perhaps air. I now turn off sensors and do not notice any drift. When it happened, I remembered manuals warning on it and assumed it was sensors on water. Cannot be definitive.

And which setting exactly are you switching off?