The Wookiee
lvl.2
Flight distance : 8924 ft
Australia
Offline
|
Sorry to dig up an old thread just ran across this searching for how safe it is to fly over water.
I am a rookie pilot myself, but I think I cracked the code as to what went wrong for this pilot.
I do fly over water a lot but I do not fly low altitude above water as I am also living in fear the drone will somehow sink (more on that in a moment) however competent with technology and networking technologies having done formal training in the fields.
After reading the first OP post and watching the last moments of the drone and roughly the first page of the thread, I have some thoughts.
1. Mavic Air and flying location
Wifi does not perform so great when it must travel through concrete or solid rock formation. The pilot was clearly flying quite close to large bodies of the earth rock without a direct line of sight to the controller IRC.
Exert from Google SearchThe Mavic Air does not have Ocusync, it uses WiFi instead, this could have contributed to the loss of signal suddenly, <------
2. RTH was used
Shocking I know but from the footage, I would feel more comfortable if the drone was told to hover in place as being cavernous and over water, at the low height, I would not trust it to correctly detect the home point due to potential interferences from the rocks and or possible poor GPS signals when flying near the caverns. It may try to fly up and crash into the ceiling as those things do not have collision detection at the rear or the top or sides.
3. Pilot Error
DJI suggested a best practice to disable the Vision Positioning System when flying over water.
Direct Quote from DJI Website
"Disable Vision Positioning System (VPS)All DJI drones come equipped with VPS, a technology that maps the surface below to help position the drone. When flying over water, however, light reflecting off of the surface can cause issues with this technology. Because of this, it’s best to maintain a height of at least two meters above the water. If you have to fly below this height for a special shot, we recommend you turn off the VPS to avoid any unstable actions by the drone. Caution: When you disable the VPS of your aircraft and the distance between water surface and drone is smaller than 2 meters, you should fly the drone with a low speed in your FOV (field of view). Also, the height needs to be adjusted frequently since the aircraft could possibly drift downwards. Be aware that the minimum height has to be above 1 meter when flying over water."
Source:https://store.dji.com/guides/how-to-fly-safely-over-water/
So I think what may have happend here is a combination of loss of wifi signal or short intterupted burst in combination of drone being told to go home while being close proximity to the home point of which GPS accuracy would or may detect as close enough to begin to descend, ontop of a large body of flat water refracting the sensor reading of the VPS under the Mavic Air so it bugged out and procceded to land.
I could very well be wrong but that is just my opinion of the possible event leading to unforunate fate of this poor pilots cool drone.
P.S
I do fly over water though I prefer to fly at higher altittude so that in the event it does something strange I have ample time to manually take over, one other thing I am contemplating getting is water pontoone leg extentsion kit for times where I would be doing arial photography over bodies of water so in the event it tried to land on water it could safely do so provided the water is calm I could then simply just take off again and land it back ashore.
Edit
I see now the other user-posted the issue
"In the range 5-20m, if you want the drone to come back to the Home point safe at +2.5m (as described in the manual) you need to activate the option "RTH at current altitude"
Okay so basically that falls into my the close proximity thing I mentioned where GPS lock reckons it was close enough to descend near the home point. So future reference for me make sure my home point is a good 20m+ away from the body of water and manually set my failsafe and RTH height to something sane which I normally do.
|
|