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Dangers of flying over water
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8183 68 2017-12-28
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Bulldog
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Can the community please tell me why flying over water can be hazerdous. I know if you crash, it's gone. But I want to discuss the other issues such as radio problems. All help would be welcomed, as I fly a fair amount over lakes. Thanks everybody.
2017-12-28
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ny300z
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Besides the obvious you mentioned there are no other dangers. 95% of my flights the last 3 years have been over water since I am on a island and the open water is good for reception if anything.

go for it man
2017-12-28
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Griffith
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Just beware that winds over the ocean may be different than over land.  Be prepared to switch to Sport Mode to get the bird back to terra firma.   Make sure you'r height will accommodate swells :-)
2017-12-28
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Jffoto
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And if you fly close to the water surface the down sensors maybe cant read the surface very good so it can be unstable.
2017-12-28
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sica
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flying over water becomes dangerous only at low altitude - below 15Meters when video and ultrasonic sensors are activated. water reflection and waves produce erroneous distance reading from the ground (water in our case) Although the MP is at 8 meters in the air the sensors may mistakenly indicate that you are at 2 meters or vice versa .. at 14 meters. This immediately leads to processor error flight MP .... and CRASH!
2017-12-28
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Swedrone
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Deactivate the downward sensors. And if there are no waves, it´s really flat
2017-12-28
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ny300z
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sica Posted at 2017-12-28 08:38
flying over water becomes dangerous only at low altitude - below 15Meters when video and ultrasonic sensors are activated. water reflection and waves produce erroneous distance reading from the ground (water in our case) Although the MP is at 8 meters in the air the sensors may mistakenly indicate that you are at 2 meters or vice versa .. at 14 meters. This immediately leads to processor error flight MP .... and CRASH!

just curious, if the MP miscalculates its height above water how could that cause it to crash?

I fly mine under 5 meters from the surface a lot with no issues or warnings but curious if thats risky with the MP. I used to fly my phantom 3 a foot above the water.
2017-12-28
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Hitmax
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Hi Bulldog - I fly mine over water a fair bit have a look at this video
2017-12-28
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sica
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Swedrone Posted at 2017-12-28 08:42
Deactivate the downward sensors. And if there are no waves, it´s really flat

Not recommended ! Your own risc ... or not recomended for begginer pilots  !
2017-12-28
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Lamplighter55
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Water overflight gets into 'advanced/experienced' piloting territory the closer you get to the surface. Basically don't think the technology is going to get you out of trouble if things start to play up!
2017-12-28
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Dirty Bird
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I fly over water all the time.  No worries mate!






2017-12-28
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A CW
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Flying at low altitude over water can effect the VPS but if this is switched off or you're flying >15M ASL then the only problem is if you crash the drone is 100% gone! Other than that there are no issues.
2017-12-28
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ny300z
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A CW Posted at 2017-12-28 10:11
Flying at low altitude over water can effect the VPS but if this is switched off or you're flying >15M ASL then the only problem is if you crash the drone is 100% gone! Other than that there are no issues.

how would affecting VPS make the drone crash? i still dont get it. I have VPS on flying under 10 meters from the water all the time without any issue/warning.
opening shot of this video i am no more then 4 feet above the water and i routinely fly this low and even lower.

2017-12-28
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jcgoobee
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I fly over the water (lakes mainly, ocean, rarely) all the time but I do keep a safe distance of 10 meters above the water level, at the minimum. Also, I don't use Sport mode while flying over water too.
2017-12-28
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Griffith
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how would affecting VPS make the drone crash?

If VPS detects surface within a couple of feet or so, it will attempt to land and shut off the props :-(
2017-12-28
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A CW
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ny300z Posted at 2017-12-28 10:14
how would affecting VPS make the drone crash? i still dont get it. I have VPS on flying under 10 meters from the water all the time without any issue/warning.
opening shot of this video i am no more then 4 feet above the water and i routinely fly this low and even lower.

From DJI's manual: - The performance of the Forward and Downward Vision Systems are affected by the surface being flown over. Ultrasonic sensors may not be able to accurately measure distances when operating above sound-absorbing materials and the camera may not function correctly in suboptimal environments. The aircraft will switch from P-mode to Atti mode automatically if neither GPS nor Forward and Downward Vision Systems are available. Operate the aircraft with great caution in the following situations:
Flying over monochrome surfaces (e.g. pure black, pure white, pure red, pure green).
Flying over a highly reflective surfaces.
Flying at high speeds of over 22mph (36kph) at 2 meters or over 11mph (18kph) 1 meter.
Flying over water or transparent surfaces.
Flying over moving surfaces or objects.
Flying over inclined surfaces that will detect sound waves away from the aircraft.
Flying over small objects (e.g. tree branches and power lines).
Flying in an area where the lighting changes frequently or drastically.
Flying over extremely dark (lux < 10) or bright (lux > 100,000) surfaces.
Flying over surfaces that can absorb sound waves (e.g. thick carpet).
Flying over surfaces without clear patterns or texture.
Flying over surfaces with identical repeating patterns or textures (e.g. tiling).
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ny300z
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Griffith Posted at 2017-12-28 10:20
how would affecting VPS make the drone crash?

If VPS detects surface within a couple of feet or so, it will attempt to land and shut off the props :-(

The mavic auto lands when its within a couple feet of the ground? i never heard that or saw that happen.
As far as i know the mavic lands when very close to the ground and you HOLD the left stick down. It never autolands
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ny300z
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A CW Posted at 2017-12-28 10:22
From DJI's manual: - The performance of the Forward and Downward Vision Systems are affected by the surface being flown over. Ultrasonic sensors may not be able to accurately measure distances when operating above sound-absorbing materials and the camera may not function correctly in suboptimal environments. The aircraft will switch from P-mode to Atti mode automatically if neither GPS nor Forward and Downward Vision Systems are available. Operate the aircraft with great caution in the following situations:
Flying over monochrome surfaces (e.g. pure black, pure white, pure red, pure green).
Flying over a highly reflective surfaces.

thanks for posting that but correct me if i am wrong, it says the only thing that could happen is it can switch to ATTI mode but ONLY if you have neither Vision System or GPS.
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A CW
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ny300z Posted at 2017-12-28 10:26
thanks for posting that but correct me if i am wrong, it says the only thing that could happen is it can switch to ATTI mode but ONLY if you have neither Vision System or GPS.

It basically increases the risk that the VPS will not detect the water so at low altitude flying over water it can cause issues. A gust of wind pulling the drone downward and it's the last time you'll ever see it. There are many scenarios where you will increase the risk. The VPS can also malfunction trying to scan the 'ground' - there are many videos on YT of drones suddenly reacting adversely over water and being lost. Also note that DJI care refresh does NOT cover total loss - the drone needs to be returned. I guess thats why the manufacturer who built your drone advises against it...
2017-12-28
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ny300z
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A CW Posted at 2017-12-28 10:33
It basically increases the risk that the VPS will not detect the water so at low altitude flying over water it can cause issues. A gust of wind pulling the drone downward and it's the last time you'll ever see it. There are many scenarios where you will increase the risk. The VPS can also malfunction trying to scan the 'ground' - there are many videos on YT of drones suddenly reacting adversely over water and being lost. Also note that DJI care refresh does NOT cover total loss - the drone needs to be returned. I guess thats why the manufacturer who built your drone advises against it...

that makes sense. Its basically has a few associated risks which is common sense and DJI is just covering their a$$ but does it work OP? yes, 100%.

lets be real, that list is a little ridiculous. Most people fly in most those conditions all the time.

2017-12-28
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A CW
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ny300z Posted at 2017-12-28 10:25
The mavic auto lands when its within a couple feet of the ground? i never heard that or saw that happen.
As far as i know the mavic lands when very close to the ground and you HOLD the left stick down. It never autolands

The Mavic has 'landing protection' built into the VPS and if it detects a level surface with no reflectivity it WILL land to the ground and shut down. If it can not detect the surface (doesn't know its there) it will land in the sea...
2017-12-28
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ny300z
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A CW Posted at 2017-12-28 10:37
The Mavic has 'landing protection' built into the VPS and if it detects a level surface with no reflectivity it WILL land to the ground and shut down. If it can not detect the surface (doesn't know its there) it will land in the sea...

If thats true then thank you i did not know that and will look into it. It seems far fetch but maybe I have just been lucky because my drone has been hovering feet off the water watching surfers and never auto landed.
2017-12-28
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A CW
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ny300z Posted at 2017-12-28 10:36
that makes sense. Its basically has a few associated risks which is common sense and DJI is just covering their a$$ but does it work OP? yes, 100%.

lets be real, that list is a little ridiculous. Most people fly in most those conditions all the time.

No, if you wish to be 'real' flying a drone at an altitude of less than 15M with VPS engaged over large bodies of water may lead to you losing the drone for good as the VPS may malfunction. How would DJI make $$$£££ advising not to do it if their insurance doesn't cover it. You've been lucky but it's not best practice to advise new pilots on here to fly their drones against what is clearly stipulated as safe flight in the manual...
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Griffith
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ny300z Posted at 2017-12-28 10:25
The mavic auto lands when its within a couple feet of the ground? i never heard that or saw that happen.
As far as i know the mavic lands when very close to the ground and you HOLD the left stick down. It never autolands

I think what happens is that if VPS finds ground within a couple of feet and has sufficient  closing  velocity, it will attempt to autoland to avoid an imminent crash. (Can't remember if the props actually shut down w/o sticks, but I think they do)  Closing  velocity can be due to either downward AC movement or rising surface.  I've actually replicate this, but it's been a few months (and versions) ago.
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A CW
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Griffith Posted at 2017-12-28 10:45
I think what happens is that if VPS finds ground within a couple of feet and has sufficient  closing  velocity, it will attempt to autoland to avoid an imminent crash. (Can't remember if the props actually shut down w/o sticks, but I think they do)  Closing  velocity can be due to either downward AC movement or rising surface.

It does autonomously disarm the motors upon landing.
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ny300z
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A CW Posted at 2017-12-28 10:42
No, if you wish to be 'real' flying a drone at an altitude of less than 15M with VPS engaged over large bodies of water may lead to you losing the drone for good as the VPS may malfunction. How would DJI make $$$£££ advising not to do it if their insurance doesn't cover it. You've been lucky but it's not best practice to advise new pilots on here to fly their drones against what his clearly stipulated as safe flight in the manual...

well the OP should make his own conclusions based off multiple opinions not just the manual. Hence why he asked here rather then just reading the warnings in the manual.

Good to state your opinion to him but dont want to scare a new pilot into never using his drone outside a wide open field either. I was just looking for clarity in the statements made.

have fun flying, so will I
2017-12-28
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A CW
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ny300z Posted at 2017-12-28 10:47
well the OP should make his own conclusions based off multiple opinions not just the manual. Hence why he asked here rather then just reading the warnings in the manual.

Good to state your opinion to him but dont want to scare a new pilot into never using his drone outside a wide open field either. I was just looking for clarity in the statements made.

Cool and I trust we won't see you on here if you lose your drone flying at 10M above the sea claiming that the drone malfunctioned and you want it covered by the warranty as it won't be - that will be pilot error!
Happy new year!
2017-12-28
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ny300z
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Griffith Posted at 2017-12-28 10:45
I think what happens is that if VPS finds ground within a couple of feet and has sufficient  closing  velocity, it will attempt to autoland to avoid an imminent crash. (Can't remember if the props actually shut down w/o sticks, but I think they do)  Closing  velocity can be due to either downward AC movement or rising surface.  I've actually replicate this, but it's been a few months (and versions) ago.

thanks, i plan on testing asap by just taking off then coming down and hovering below 5 feet and see if it autolands without me doing anything
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A CW
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ny300z Posted at 2017-12-28 10:51
thanks, i plan on testing asap by just taking off then coming down and hovering below 5 feet and see if it autolands without me doing anything

It only works using RTH... I suggest you read the manual.
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ny300z
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A CW Posted at 2017-12-28 10:51
Cool and I trust we won't see you on here if you lose your drone flying at 10M above the sea claiming that the drone malfunctioned and you want it covered by the warranty as it won't - that will be pilot error!
Happy new year!

haha no need because i have insurance on the drone that covers anything unlike the DJI refresh.

OP have fun flying but beware of fake news.
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Griffith
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ny300z Posted at 2017-12-28 10:47
well the OP should make his own conclusions based off multiple opinions not just the manual. Hence why he asked here rather then just reading the warnings in the manual.

Good to state your opinion to him but dont want to scare a new pilot into never using his drone outside a wide open field either. I was just looking for clarity in the statements made.

I hope he is not scared off.  He wanted to know the limits of safety.  Basically communication is good, but watch the winds stay away from the surface until you have experience and know the limitations of the AC.  
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ny300z
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A CW Posted at 2017-12-28 10:54
It only works using RTH... I suggest you read the manual.

autoland only works in RTH? then why are we talking about it
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A CW
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ny300z Posted at 2017-12-28 10:55
haha no need because i have insurance on the drone that covers anything unlike the DJI refresh.

OP have fun flying but beware of fake news.

Well the OP may not have insurance so again, best to give sound advice by knowing your subject.
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Griffith
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ny300z Posted at 2017-12-28 10:41
If thats true then thank you i did not know that and will look into it. It seems far fetch but maybe I have just been lucky because my drone has been hovering feet off the water watching surfers and never auto landed.

my drone has been hovering feet off the water watching surfers and never auto landed.

I presume you're speaking of 5-10 feet above the surface - plenty of safety margin.  Curious - do you also have VPS disabled?  
I sometimes do a fast skim of the shoreline in Sport Mode at about 5 feet, but over the open water I like to be a little higher :-)
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A CW
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ny300z Posted at 2017-12-28 10:57
autoland only works in RTH? then why are we talking about it

Post number 15 I believe.
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Griffith
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ny300z Posted at 2017-12-28 10:51
thanks, i plan on testing asap by just taking off then coming down and hovering below 5 feet and see if it autolands without me doing anything

Try a relatively slow decent  to ground.  As I recall, the autolanding kicked in at about 2 feet and there had to be sufficient closing velocity. Otherwise it can hover at 2 feet all day (or all battery) without any autonomous intervention.
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AG0N-Gary
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Yes, it will land if it is too close to the ground.  YES, you can override it if you are paying attention and see it happening.  Just give it full up throttle.  When you get it up there again, it will fly normal again until you get too low.  Many a drone took a bath from this "feature".
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ny300z
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Griffith Posted at 2017-12-28 11:03
my drone has been hovering feet off the water watching surfers and never auto landed.

I presume you're speaking of 5-10 feet above the surface - plenty of safety margin.  Curious - do you also have VPS disabled?  

yes around 5 feet no less usually. VPS not disabled
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ny300z
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Griffith Posted at 2017-12-28 11:15
Try a relatively slow decent  to ground.  As I recall, the autolanding kicked in at about 2 feet and there had to be sufficient closing velocity. Otherwise it can hover at 2 feet all day (or all battery) without any autonomous intervention.

thanks, that is what I was asking about, i didnt think it would just land if hovering or flying low.
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rolling56
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Here's something to throw in the mix
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