Hello,

New to Forum Thanks! Went out with my 4 month old phantom 4. flying over lake @ Approximately 65 ft AGA,  distance 1434 ft.  Remote lost connection, no return to home,  have flight video, no clues on video, it just stops, like a complete loss of power? Flight record just stops in middle of lake.  Tried to retrieve drone based on last gps coordinates, but water to murky to see bottom.  Why would this happen? Will DJI honor warranty?


I think I attached flight record


Thanks!  

https://healthydrones.com/main?f ... amp;page_id=GENERAL

http://www.phantomhelp.com/LogViewer/EOC7BIKT906X975JVXTB/

The log stops with 1 second to go before you hit the water at 40mph with the throttle full down...

What does the video show?   Must be able to see the water approaching...

Nigel_ Posted at 2017-6-8 16:04
The log stops with 1 second to go before you hit the water at 40mph with the throttle full down...

At an altitude of 76 ft? The Homepoint altitude is on my deck around 39 ft above the water so altitude above the water was approx 37+39 = 76ft above water as on the log? I may not be reading it right? I fly over the lake frequently and 10 ft above the water is -29ft on the DJI GO app.  I think I am reading the flight record correctly?

Nigel_ Posted at 2017-6-8 16:08
What does the video show?   Must be able to see the water approaching...

Nothing, at approx 80 ft then stops,  

fans4d7b4779 Posted at 2017-6-8 16:16
At an altitude of 76 ft? The Homepoint altitude is on my deck around 39 ft above the water so altitude above the water was approx 37+39 = 76ft above water as on the log? I may not be reading it right? I fly over the lake frequently and 10 ft above the water is -29ft on the DJI GO app.  I think I am reading the flight record correctly?

OK, I couldn't tell how far down the water was, that would be be 6 seconds to impact, but as you got close to the water you lost signal, trees in the way?  There are an increasing number of missed samples in the log, the last sample logged is after 9 missed ones.  It should stop due to lost signal after 3 seconds, but in sports mode at full speed forward and full speed down it does not stop instantly, another 3 seconds of braking would put it in the water.   Seems like the most likely explanation.

It appears that your VPS was seeing things when it shouldn't have, do you have anything added like a gimbal guard or landing gear extensions?

Nigel_ Posted at 2017-6-8 16:34
OK, I couldn't tell how far down the water was, that would be be 6 seconds to impact, but as you got close to the water you lost signal, trees in the way?  There are an increasing number of missed samples in the log, the last sample logged is after 9 missed ones.  It should stop due to lost signal after 3 seconds, but in sports mode at full speed forward and full speed down it does not stop instantly, another 3 seconds of braking would put it in the water.   Seems like the most likely explanation.

It appears that your VPS was seeing things when it shouldn't have, do you have anything added like a gimbal guard or landing gear extensions?

Thanks! No add on' s the drone. Where are you  getting all of the data? Off of the phantomhelp log?  I was flying with direct and FPV, I have only 70 hours of flying experience with this drone, but am pretty confident that I was at considerable altitude.   

fans4d7b4779 Posted at 2017-6-8 16:42
Thanks! No add on' s the drone. Where are you  getting all of the data? Off of the phantomhelp log?  I was flying with direct and FPV, I have only 70 hours of flying experience with this drone, but am pretty confident that I was at considerable altitude.

For some reason at the end of the log it rolls a bit as though it got hit by a gust of wind, looks a bit odd but I don't see any possible explanation other than wind.  Everything else seems normal except the loss of signal.

From your viewpoint on the right side of your patio, there is a gap in the trees at the bottom of the garden giving you a view over the water, but towards the end of the log the aircraft seems to be heading behind the trees out on the end of the promontory which look reasonably tall, I assume that is what caused the signal loss, are they tall enough to have blocked line of sight at low altitude?

The last line in your flight data shows that you were on the edge of losing signal and it's highly likely that you did lose signal after that.
At the time you had been flying in Sport Mode with the left stick hard down for 26 seconds and getting closer to the water at a rate of 12 ft/sec.
The Phantom had a horizontal speed of 40 mph as well as the vertical component.
This doesn't leave much room for alternative outcomes.
It looks like you flew into the lake at speed.

Promontory...I am definitely using that when I sell my house. We call them peninsulas here:> View is quite wide of the lake Just check another log when I landed on the ice and the actual lake altitude is -42.6 ft relative to the deck I launch from.  The view of the lake from the deck is quite wide, but yes the drone was behind the promotory when the incident happened probably right at the tree line.

I still cannot figure out how you are are getting all of this data from either of my links i.e. rolls a bit and, sensor data?

Thanks for your help   

fans4d7b4779 Posted at 2017-6-8 17:47
Promontory...I am definitely using that when I sell my house. We call them peninsulas here:> View is quite wide of the lake Just check another log when I landed on the ice and the actual lake altitude is -42.6 ft relative to the deck I launch from.  The view of the lake from the deck is quite wide, but yes the drone was behind the promotory when the incident happened probably right at the tree line.

I still cannot figure out how you are are getting all of this data from either of my links i.e. rolls a bit and, sensor data?

Here, a peninsula tends to be a mile or ten long, promontories are normally under a mile, although they should have some high land at the end.  If it didn't have the trees on it then I would probably call it a "spit".

My information isn't all correct - you were sitting on a deck, not a patio!  

I don't think there is going to be a way to prove what happened without the log from the drone itself, and since it landed in water that may have got corrupted anyway.   Altitude from the barometer isn't always accurate over time, if the air over the water was substantially warmer or colder than the air over the land then it could have been 10 or 20ft out by the end of the flight and it was going to be close if you add another 3 seconds + braking distance to the last record.  Also I find that when you do a sudden stop from full forward in sports mode you tend to loose a little extra height.

So without proof of a fault and a good possibility of hitting the water I don't think there is any chance of a warrantee claim, especially as you had flown it out of signal range.

You were heading for the water, hitting it seems the most likely explanation, unless someone can come up with a better explanation...

Nigel_ Posted at 2017-6-8 18:38
Here, a peninsula tends to be a mile or ten long, promontories are normally under a mile, although they should have some high land at the end.  If it didn't have the trees on it then I would probably call it a "spit".

My information isn't all correct - you were sitting on a deck, not a patio!  

I guess I'll go with your expertise, it's hard for me to wrap my head around 81 feet of altitude loss after lost signal, even at 40 mph horizontal and 10 mph vertical speed.  When maneuvering in at similar speeds and letting go of sticks it doesn't seem like  it continues for that distance.  That is like the height of our tallest trees.

Thanks for all of your input!

fans4d7b4779 Posted at 2017-6-9 06:15
I guess I'll go with your expertise, it's hard for me to wrap my head around 81 feet of altitude loss after lost signal, even at 40 mph horizontal and 10 mph vertical speed.  When maneuvering in at similar speeds and letting go of sticks it doesn't seem like  it continues for that distance.  That is like the height of our tallest trees.

Thanks for all of your input!

Like you say, 81 feet would be like the height of your tallest trees, in which case it would not have lost signal by going behind those trees out on the promontory which are standing on ground around 30 foot below your control location.  But it did loose signal so was probably below 81 foot...

You can synchronise your flight in the Go App, contact DJI support, and request they take a look at the log, maybe they will see something we have missed and send a free replacement, maybe they will just be nice and give you a discount on a replacement. I guess they will come to the same conclusion and say it's not a warranty issue.

Nigel_ Posted at 2017-6-9 07:44
Like you say, 81 feet would be like the height of your tallest trees, in which case it would not have lost signal by going behind those trees out on the promontory which are standing on ground around 30 foot below your control location.  But it did loose signal so was probably below 81 foot...

You can synchronise your flight in the Go App, contact DJI support, and request they take a look at the log, maybe they will see something we have missed and send a free replacement, maybe they will just be nice and give you a discount on a replacement. I guess they will come to the same conclusion and say it's not a warranty issue.

Agree, here was a similar flight where I ended up finding the drone upside down on the ice. Do the logs have an explanation for what happened here? Thanks!

http://www.phantomhelp.com/LogViewer/MEX9J75UIQRYIXQL3MED/

Slalom Posted at 2017-6-10 11:46
Agree, here was a similar flight where I ended up finding the drone upside down on the ice. Do the logs have an explanation for what happened here? Thanks!

http://www.phantomhelp.com/LogViewer/MEX9J75UIQRYIXQL3MED/

You took off, gained height to 3m (10ft) and set off across the ice.

The aircraft maintained the 3m barometer height, but I guess the air out on the lake was warmer than on the land resulting in the barometer reading a little too high so the aircraft dropped to maintain the barometers 3m altitude.

The inaccuracy of the barometer varies a bit as you fly out over the lake but from the ultrasonic sensors we can see that it starts off at 2.9m (9.5ft) and when you put it into sports mode near the end it is at 1.3m (4.3ft), reaching 0.7m (2.3ft) at one point on the way.

When you put it into sports mode, the speed increase seems to affect the barometer and it looses more height.  I think it is inevitable that high speed is going to affect the air pressure measured by the barometer a little, the aerodynamics are always going to make it hard to keep a perfect measurement, I think most people see a couple of meters inaccuracy on the Phantoms in sports mode.

2 seconds after entering sports mode with full speed forward plus a little sideways on the stick, the barometer is still reading 3.1m (10.2ft), the ultrasonics are seeing 0.4m (3.1ft), but it is leaning forward at 40 degrees due to accelerating to full speed in sports mode, currently at 30mph, so the ultrasonic sensors are not pointing straight down, due to the angle it will have been lower than 3.1ft off the snow/ice.

Then one of the landing gear legs hits something, maybe only one hits flat ice because you have a little sideways on the stick, but it spins around violently and rolls over, apparently taking only 0.3 seconds to end up upside down, after that the detail is lost due to gaps in the data due to bad reception.   

Not sure why you lost reception at the end, could be due to being too close to the ice and an extremely low angle for the radio waves to travel back, they are being absorbed by the ice even though they are a little above it, or maybe you flew behind one of those trees on the end of the peninsula again.  

Doesn't appear to have fallen, it just flew into the ice/snow at 31mph and 0 altitude while tilted slightly sideways and leaning forwards at 40 degrees.

Ok I am confused on something,,?? in the manual it says that if you fly over water the sensors on the aircraft will not work properly therefore giving false readings according to DJI. On the RTH if you had it set on 80 foot and the trees are 81 and you are over water and confusing the sensors would that have a direct effect on it being able to return? I have mine set at 100 foot giving the trees around the area I am in are about 60-75 feet, this gives unobstructed view to the AC, the only variance is I am not over water except for a river that is not that wide and I do avoid at low level and only cross it side to side.

SargeAF Posted at 2017-6-14 10:59
Ok I am confused on something,,?? in the manual it says that if you fly over water the sensors on the aircraft will not work properly therefore giving false readings according to DJI. On the RTH if you had it set on 80 foot and the trees are 81 and you are over water and confusing the sensors would that have a direct effect on it being able to return? I have mine set at 100 foot giving the trees around the area I am in are about 60-75 feet, this gives unobstructed view to the AC, the only variance is I am not over water except for a river that is not that wide and I do avoid at low level and only cross it side to side.

It is only the downwards vision sensors used for visual positioning (VPS) that have an issue with water, the front vision sensors used for obstacle avoidance will carry on working normally and avoid the tree.

Although it is not a good idea to use them against trees regularly since they aren't guaranteed to see small branches.

The problem with water is that the aircraft may try to hold position relative to waves moving across the water surface so it's actual position may drift.

My advice is don't listen to Nigel he makes a habit of getting to involved in these cases . He feed me the same crap about how false sensor readings are caused by user error. Nigel fly's his drone in a little daisy field. And talks like every thing he says is a fact . When truth is he makes it up as he goes along and the narrative is always the same user error and DJI not at fault. Just surprised he is yet to accuse you of breaking the law

Put in your warranty claim and put your case across .I got a refund through the retail unit I got it from when the sensors failed  . And seek advice from others as unfortunately a handful of dji forum warriors bang the same drum every day on here. Good luck

So I got this response today. Perhaps they can see more data on there flight record analysis then we can see?  I believe the drone must have contacted the water after it lost connection. Like 6 seconds after lost connection. Any ideas of how to escalate a case with DJI?

Thanks for your patience.

For your claimed case CAS-700126-Y8K3W6, we have already finished the analysis, and the result is as follows:

1. The aircraft was fully controlled by pilot during the flight;
2. T=13-27, h=11m, d=437m, flight record was cut off when the aircraft was in Sport mode; Pilot pulled down throttle and pushed pitch forward; the aircraft flew forward and descended into water at 4m/s;


According to the analysis, the incident was not caused by any product malfunction factors. As such, we could not provide warranty service.

Should you have more questions, please feel free to let me know.

Best Regards,


Sophia
DJI Tech Support