Critically low battery landing, why ?

[walterbenedikter]

With the battery at 69% and a voltage of 3.74 my phantom 3 Pro decided to land. Problem is that it was 4500 feet in altitude and above water. Due to the sun rising I could not see it until he was only 350 feet from me. As they always do with me, when they decide to go for 'RTH' or 'Landing' they report signal lost in the first seconds after deciding to do their own stint anyway. The good thing is that, although the wind was some 7 - 8 knots at surface, probably stronger higher up, he kept the horizontal position and although I had the boat ready to intercept him I could steer him into my wife's hands and slow him down for an easy catch. Here is the video from the drone's perspective, of course the thriller is in the last 10 seconds.

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Does anybody know the parameters that trigger critically low battery landing ? I only know the 10% figure and have seen them land with defective batteries at 3.4 volts even just 5 seconds after take-off with a 'full' battery. Did not expect this to happen in this situation, was actually more prepared for a RTH action. Actually he decided he wanted to land when the green segment of the battery control bar disappeared. What I also would like to know is if anybody else has experienced loss of signal right after the drone decides to go home or emergency land. In this particular situation I had perfect control and video going up all the way, recaptured signal only after a loooong while ! Do they do it on purpose ?

 

[Deleted member 62848]

Ka wow and wow again
I had auto land one and half miles out which was lucky to cancel at night above some fire breaks on a hill side,,,,I'm thinking it predicted it only enough power to get home,the parameters for battery are normally what you set them at but think mayby SRH had something to do with it
You probably have to upload the log to find out,,good it came down nice for a good catch..I'm still amazed your p3p went up that high,my p4 wouldn't even do that, I had to ly down with remote on me chest,,it probably lost signal and at that height probably took a while to regain ,did you get any option like cancel x on screen ,I could not see one,drone was not happy and thought that's it,im coming home,,,I used magnifying glass to read your height if curious ha
It does say critical low power so I'm guessing it was doing its rth prediction
Hey you know we only allowed 400ft ay
Why go so high,cool but very crazy and very risky

 

[cheddarman]

Blimey, where are you that you're allowed to fly at such altitude? 4500 feet??? Somewhat illegal I'd say, certainly here in the UK where 400ft is our limit!
You'll need to analyse your flight logs data to establish what triggered this episode.
Maybe you were "interfered with" by some government agency thinking you were a UFO at that altitude.

 

[Deleted member 62848]

?Yeh 400ft in NZ,and sure that's world wide rule ?

 

[cheddarman]

Probably ianzone as commercial/private planes have a low ceiling of 500ft!
Great view from up there though!!

 

[walterbenedikter]

Blimey, where are you that you're allowed to fly at such altitude? 4500 feet??? Somewhat illegal I'd say, certainly here in the UK where 400ft is our limit!
You'll need to analyse your flight logs data to establish what triggered this episode.
Maybe you were "interfered with" by some government agency thinking you were a UFO at that altitude.

I guess that 400 ft is an international rule, but usually I enjoy dirtbike and drone in a southern region of Russia, close to Chechnya, called Kabardino-Balkaria ... with the highest mountain in Europe and palm beachy resorts just a few hours away. There you drive without tags and fly as you please in most areas. And agencies do not care for anything that happens here. All the buildings you see in the footage are 100% illegal, too !

 

[walterbenedikter]

Ka wow and wow again13210+ mtrs up ,,where were you going lol
I had auto land one and half miles out which was lucky to cancel at night above some fire breaks on a hill side,,,,I'm thinking it predicted it only enough power to get home,the parameters for battery are normally what you set them at but think mayby SRH had something to do with it
You probably have to upload the log to find out,,good it came down nice for a good catch..I'm still amazed your p3p went up that high,my p4 wouldn't even do that, I had to ly down with remote on me chest,,it probably lost signal and at that height probably took a while to regain ,did you get any option like cancel x on screen ,I could not see one,drone was not happy and thought that's it,im coming home,,,I used magnifying glass to read your height if curious ha
It does say critical low power so I'm guessing it was doing its rth prediction
Hey you know we only allowed 400ft ay
Why go so high,cool but very crazy and very risky

Yeah, lying on the back and holding the RC with stretched arms is very important, not too close to the body ! It actually had full video signal and like 4 bars on the control signal indicator up to the moment when I saw the green bar of the predicted battery life shrink fast and actually hovered for the battery to recover. Usually an RTH would follow, and usually it cuts of control and video right after that, to regain after 3 minutes or so and then you can abort RTH and do your thing but this time it was a landing, so no way to abort all the way down. Just with full throttle I could get it to descend slower for the catch and it somehow reacted to direction changes. We had the boat's engine running but as said if the bird would have just landed without GPS and position control but guided by the wind we would not have had a chance.

 

[Deleted member 62848]

After reading this what's your battery warnings at,,mayby it calculate from 69% down to your in app battery warnings and thought it better land,,that's all I can think of but again speculation on that


I delete other post cause I muddle it all up as usual lol...
I thought auto land can be cancelled but not when its critical, it cant be cancelled

 

[Meta4]

Here is the video from the drone's perspective, of course the thriller is in the last 10 seconds.

The video is no help working out what happened.
The recorded flight data would be needed if you want any information.

Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report on the flight data.
Come back and post a link to the report it provides.

 

[svoneil]

The higher up you go the less oxygen you have. Lift becomes more problematic and harder to come by which in turn uses more battery. The drone then works harder to continue to rise so not surprised by the battery not lasting.

 

[GFields]

I'm wondering if the OP posted this to see what kind of reactions he'd get about the 4500 AGL.

 

[Capt KO]

No sympathy. Insane! ?

That said, nice boat and heck of a view.
Wife's a keeper, good catch....and good catch

 

[Andy9]

Well, be serious. It was 4300 ft that's about 1400 m. No oxygen problem there and electric driven motors do not need oxygen. LOL.
But of course he seriously violated several safty flying rules. Besides the altitude which was more than 10 times over the law limit, he could not see the drone also. Even his boat is hard to spot from that hight.
Ascending so high surely drained the batt. more than it would be at normal flight and the calculation algorythm estimated that the battery is almost enough to imediately land. Descending is much slower than elevating so it take longer time and the battery as well. If it used 31% for uplifting then for going down would be atleast 30% or more and because he didn't know where exactly the drone is and he mentioned the substantial wind, we can count at least 10-20% for finding it and so you quickly come to 10% which is the level when the landing procedure is triggered by default. So no mystery here.

 

[walterbenedikter]

Well, be serious. It was 4300 ft that's about 1400 m. No oxygen problem there and electric driven motors do not need oxygen. LOL.
But of course he seriously violated several safty flying rules. Besides the altitude which was more than 10 times over the law limit, he could not see the drone also. Even his boat is hard to spot from that hight.
Ascending so high surely drained the batt. more than it would be at normal flight and the calculation algorythm estimated that the battery is almost enough to imediately land. Descending is much slower than elevating so it take longer time and the battery as well. If it used 31% for uplifting then for going down would be atleast 30% or more and because he didn't know where exactly the drone is and he mentioned the substantial wind, we can count at least 10-20% for finding it and so you quickly come to 10% which is the level when the landing procedure is triggered by default. So no mystery here.

Thanks for the analysis. As you said, the forced landing I would expect at a battery status in the range around 10%, or in case of a faulty battery if the voltage drops to something around 3.4 volts. The data suggest that a RTH might have been indicated, as the green portion of the battery life was disappearing, but two questions arise. Why is it, and it happened every single time to me, that as soon as some return or landing procedure is triggered the RC loses control signal only to regain it so long time after that moment. Typical example, drone wants to return home when you fly against the wind, the signal is 100%, it happened to me every single time that if he starts RTH and I abort, a few seconds after I abort the app notifies signal loss. Looks to me it was by design. Second question: Descending obviously took much less battery then you might think, when I regained control I had a very healthy battery readings and a long green portion. There is an 'x' button to abort landing with no effect. Why? Is it meaningful that the drone is so smart in so many occasions and then dull enough to keep its uncontrolled descent without giving the RC the chance to intervene? Choosing the landing spot, or descending at a higher speed would be just two of the things I could think of that would not hurt.

 

[walterbenedikter]

The video is no help working out what happened.
The recorded flight data would be needed if you want any information.

Go to DJI Flight Log Viewer | Phantom Help
Follow the instructions there to upload your flight record from your phone or tablet.
That will give you a detailed report on the flight data.
Come back and post a link to the report it provides.

Thanks for the reply, I will do so as soon as I get home to Moscow. Here I am working only with my cell phone and do not have the tools to extract the flight data, I guess. Was hoping to find some information about what are the parameters set by the producer to trigger an immediate landing, as said I would have counted on a RTH that was enabled. Critically low battery landing I so far only experienced with batteries at 10% or nor charged right that have a voltage drop to below 3.5 volt. In my case it was frustrating to see the bird come down at slow speed and battery data ok, but no chance to control what he was doing. Of course it was nice to see him come down more or less to the spot where he started. Simply put, if as I heard you can abort emergency landing by switching the flight mode, why can't you abort it by pressing the abort button?

 

[walterbenedikter]

No sympathy. Insane! ?

That said, nice boat and heck of a view.
Wife's a keeper, good catch....and good catch

Thanks Captain ! We like the boat for day cruises too, just upgraded the engine to an old Mercruiser 7.4 Bravo Three. Not much electronics and much power is what I personally like in a boat. And sure thing I love my wife. Since our drones so often start and land on beaches, or snow, she is used to catching and providing a manual launch pad.

 

[walterbenedikter]

Lol well I must have read the distance traveled,I write 13210 mtrs which turns out staggering 43,339 859ft ,,it was late and I did use magnifying glass to read little digits, off to the space station I reckon,,

@Andy9 you spot on I think,,I totally agree,,I had feeling it was estimating the flight and preset values
And seriously these sort of flights give us all a bad name so bit of shame on the op ,,he dosen't seem to mind since he metion everything else below is illegal

Not getting a bad name for drone pilots is very important to me, and to avoid that I never fly close to people ... and with close I mean fly anywhere there might be people. My drones always stay miles away from people, that is why I fly in the wilderness and at odd times where you would not expect anybody to be bothered. My take is that flying in the neighborhood over other people's houses or in cities is what bothers people involved and gives us more of a bad name, don't you agree ?

 

[Deleted member 62848]

Well dispite the great view yes you made yourself look irresponsible and broke rules that we cant
This does make you look bad for drone pilots
What's the purpose of this flight--fun and games,it had no real purpose, remember planes can come out of nowhere, what if it done the worst and wind carry it off somewhere, terminal velocity of a brick be pretty dangerous,,who cares if it was over water,seems you know the rules but flaunt them cause everything is illegal there and no one cares,probably lucky no one report you,lots of eyes on this forum,,
As for flying over houses it does make a few unhappy and always a risk of major like errors that shut your drone off in flight which myself and others have experienced first hand,,my p4 only freefall from 72ft and smashed concrete roof tiles on my own house luckily but goes to show things can go bad..also you not following rules of flight sets bad example since you dont want to give drone pilots a bad name,you have achieved that by showing a flight that breaks all the rules and for the world to see..I'm no drone police and cant tell you what to do but dont put others at risk for your enjoyment, your sort of lucky it autoland and not drift away with high winds that rth cant fight,man be careful ay,,I respect all but yes slight moan at you,sorry for that but your flight shows lot of risk and to get your drone back is a fluke,take care out there ?

 

[Andy9]

Not getting a bad name for drone pilots is very important to me, and to avoid that I never fly close to people ... and with close I mean fly anywhere there might be people. My drones always stay miles away from people, that is why I fly in the wilderness and at odd times where you would not expect anybody to be bothered. My take is that flying in the neighborhood over other people's houses or in cities is what bothers people involved and gives us more of a bad name, don't you agree ?

Correctly! You are right. Only that aircraft fly at such altitudes.

 

[walterbenedikter]

Correctly! You are right. Only that aircraft fly at such altitudes.

Yeah, I am a pilot myself and sometimes I fly around 3 k or 4 k feet altitude when I just need to fly away my yearly hours to keep the license alive. Commercials you would see here under 6000 only close to landing or take off and during pilot training, when they have a bunch of pilots on board and repeat landing and take off and return right back to the approach for the next one to go ... but that you would have only near airports. And of course helis you will find in these slices.

Maybe I have mentioned this before, the only reason I flew up from the boat is that some friends of local politicians built their houses near a beautiful public beach and thus the beach became only accessible by boat. I wanted to see for myself which private roads they built and how they fenced the area off. I had tried to fly from their gates towards the beach, as their houses are ALWAYS abandoned but could not find the beach. Rest assured I do not do this just for fun and normally I have the altitude limit set at 120 m. Except I fly up along a mountain but then keep under 120m from the ground, not the takeoff position. And there I am really far away from people and planes, altitudes above sea level 4000 to 5000 meters where I love to trek.

Thanks for your opinion! Fly safely.