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Well, I Had Hoped it Would NOT be Inevitable!!
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tvl
lvl.4
Flight distance : 197779 ft
United States
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As careful & cautious as I have been, I experienced my very first crash today. I'm not even sure it was my fault, although I am very aware of the CSC command and what will occur. Here are the facts:

1- I just recently purchased some ND filters and wanted to go out in the back yard and simply take the drone straight up and take a couple of quick videos to see if there was much difference in video quality with the ND 16 filter in place.

2- Ascended to approximately 200 feet and took a couple of quick videos as I rotated the craft a small amount. I then began bringing the craft down and as it reached an altitude of approximately 50 feet, the motors shut off and it naturally fell straight to the ground. It landed about 20 feet from where I stood.

3- Three props were broken.

4- The gimbal took a hard hit! At the top of the gimbal where it attaches to the drone, there is a piece that bends downward 90 degrees and then the camera assembly attaches to the bottom portion of this arm. The arm was actually twisted just where it turns downward. Therefore, if not repaired or replaced, I will most assuredly have a severly tilted horizon.

5- The bottom gray cover just above the gimbal assembly was damaged as it struck the ground, which also broke 3 tabs on the bottom white housing. Therefore, the gray cover can not be reattached firmly because the screws have nothing to screw into.

6- One motor was packed with soil and did not turn easily. I managed to clean it up and the prop seems to spin OK, but I feel it doesn't turn quite as easily as the other 3.

7- I cleaned up everthing, replaced the props and powered it up. The gimbal obviously has some damage; if nothing more than a twisted bracket. It does however make a somewhat audible grind when going through the power up procedure, which was not there before. I did fly the craft for a couple of minutes with a error:  "forward vision sensor calibration error", which may go away if I calibrate everything once again. It did seem to fly OK for the brief checkout and I only ascending to about 15 feet.

8- There may be other damage that I am not aware of, but I think this is it - at least I would hope so!!

Querstion 1 - OK, while I am not saying I didn't make the dreaded CSC command, I honestly don't think I did! But what else would shut off the motors? If it was a fault of the drone, how can it be proved and is this easy? I'm generall very methodical and take my time with everything and feel I was flying the craft properly but ??????

Question 2 - I see where some have uploaded flight logs which some on this site can interpret. Where do these logs reside so that I can collect them and post them if necessary?

Question 3 - What hurts the most is the waste of money because of the somewhat ruined craft and it is ONLY 15 days old. I really don't know the true extent of the damage and if this thing can be trusted to go far at all. It needs to be checked out. And, without a clear "who is at fault", I guess I may have to bear the expense.

Question 4 - What is the process of getting a drone repaired  -  how long does it normally take  -  what is the most it would cost? And more importantly, would my drone be repaired and returned to me OR would I most likely just receive a refurbished unit that may have other issues?

I'm debating whether just to sell everything - everything worked flawlessly up unitl today ............... but, what may be ahead of me now is my main concern! Again, I honestly don't think this was operator error, but if I'm totally honest, I can't be 100% sure. DJI will most likely take advantage of the uncertainty.

Question 5 - Is it easy to sell the remaining "parts" so that the loss isn't so bad?

I'm sorry for the somewhat long post! I'm just "sick" in the gut for now. My intention was to never have a crash or mishap. What a foolish expectation! However, these drones aren't cheap and a crash simply adds more money to the heap!
2017-2-11
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WindSoul
lvl.4
Flight distance : 16 ft
Canada
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Q1. that you were pulling on left stick down, even all way, should not have stopped the motors unless you pressed RTH at the same time. only an analysis of the flight logs could reveal exactly what commands you actullay sent to the drone.
Q2. the telemetry logs should be in the DJI GO 4 app. you should be able to see themif you click on top right corner. there are detailed logs inside an sd card located inside the drone, but those are for service

For the rest of questions, I have no expertise to answer.

I have myself started a poll as to see how people feel about a dedicated switch for start/stop motors. I still believe is important DJI implemented a foolproof method rather than use flight sticks. You may want to visit the poll (on Phantom 4) and contribute with your vote. I have to warn you that you will see lots of uncalled for and bullying in the replies. some including captains, people who are supposed to know better!


2017-2-11
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Labroides
Captain
Flight distance : 9991457 ft
Australia
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Go to http://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record from your phone/tablet.
Come back and post a link to the report it provides and it may shed some light on the incident.
2017-2-11
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tvl
lvl.4
Flight distance : 197779 ft
United States
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WindSoul stated:  "that you were pulling on left stick down, even all way, should not have stopped the motors unless you pressed RTH at the same time"

Without a doubt, I am 100% certain I did not push on the RTH button. And naturally, the left stick was being pressed in a downward position to return the craft to its landing position. I do recall nudging the right stick a small amount during the descent to re-position the craft a small amount since it had drifted just slightly. But that is about it!
2017-2-11
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Odan
Second Officer
Flight distance : 182913 ft
United States
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What you need to do is cool down and take a breath.  Send it in for repair. I've seen some pretty screwed up drone crashes on
this forum and I don't think I've seen a repair bill more then $250.oo
You don't really understand how easy it is to have your thumbs go crazy and you don't even know it.
Having learned on RC Heli's  I have had my share of "DUMB THUMBS"  that's the term for it.
I read you made some last minute adjustments @ 50ish feet.  Your thumbs might have moved faster then you think.
It's happened to me way too many times with helis.
Wait and see what DJI tells you before you start slashing them.
You have a 50-50 chance because it is either a PE or equipment.
As for selling the junk...None of it could be trusted....who would buy it anyway ?
Get it fixed and see how you feel later  
2017-2-11
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Labroides
Captain
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Australia
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tvl Posted at 2017-2-11 16:04
WindSoul stated:  "that you were pulling on left stick down, even all way, should not have stopped the motors unless you pressed RTH at the same time"

Without a doubt, I am 100% certain I did not push on the RTH button. And naturally, the left stick was being pressed in a downward position to return the craft to its landing position. I do recall nudging the right stick a small amount during the descent to re-position the craft a small amount since it had drifted just slightly. But that is about it!

Without data, it's all (mostly incorrect) guesswork.
Accidentally shutting down the motors in flight is one of the most unlikely possible explanations.
I'd be more interested in the condition of the battery during the flight.
Post the flight data and it may help solve the mystery.
2017-2-11
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tvl
lvl.4
Flight distance : 197779 ft
United States
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Wait and see what DJI tells you before you start slashing them.

My comments weren't meant to trash/slash DJI and I apologize if they were taken that way. However, unless one can prove without a doubt this was OR wasn't a CSC error, I feel somewhat confident that DJI will take the same course that even you have seemingly taken ............. "Dumb Thumbs". Maybe it was "Dumb Thumbs", but I honestly feel like I was being way more careful and attentive than to make that mistake. But anyway, can DJI or someone view the files from the craft and positively tell if I made the error OR will the files simply show there was a loss of power ................... which would likely make one assume the operator cut power somehow, whether it be intentionally or unintentionally?? And that is all I am saying, unless there is absolute evidence one way or the other, what chance do I have in prevailing!
2017-2-11
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tvl
lvl.4
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I'd be more interested in the condition of the battery during the flight.

I will post the flight data shortly. But just before takeoff, the battery indicated about 90% if I recall correctly. The entire flight had a duration of approximately 4 minutes.
2017-2-11
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Labroides
Captain
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Australia
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tvl Posted at 2017-2-11 16:52
I'd be more interested in the condition of the battery during the flight.

I will post the flight data shortly. But just before takeoff, the battery indicated about 90% if I recall correctly. The entire flight had a duration of approximately 4 minutes.

Had the battery been sitting for days since charging?
What was the weather like ... cold?
We'll see battery voltage data in the flight data - it's often a critical piece of data for fall-from-the-sky incidents.
2017-2-11
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Oldmaninwva
First Officer
Flight distance : 8726381 ft
United States
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You can also view a REPLAY of the last few flights from the saved data right on the phone or tablet... You can also see what your stick positions were at each point...  I use an iPad myself but I would think android would be similar...  open the app, click on the "Flight Record" (ipad in both the lower left and in the upper right pull down... Select the flight listed at the top of the right hand column then a google earth map with playback controls at the bottom and it will run thru the flight....  To the left of the start and stop playback buttons you will see an icon that ;looks like a controller.  Press that icon for the control stick overlays to the left.  you will see just what you did for the "Sticks"

2017-2-11
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tvl
lvl.4
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Well, if everything was done correctly, here is the link to the flight that ended up losing power about 50 feet above ground


Link has been removed

2017-2-11
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Nigelbrinkmann
First Officer
Flight distance : 586391 ft
Australia
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Hi, sorry to here about the crash,
Just a thought, did you have a gimbal guard fitted, this can cause the motors to stop if only the left stick was pulled right down 100% to desend.
Also as mentioned above, play back the flight records and enable the stick overlay and check if you did a CSC.
2017-2-11
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Labroides
Captain
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tvl Posted at 2017-2-11 18:37
Well, if everything was done correctly, here is the link to the flight that ended up losing power about 50 feet above ground

http://healthydrones.com/main?share=rXhOMo

Healthydrones doesn't show the info that's necessary to investigate.

Go to http://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record from your phone/tablet.
Come back and post a link to the report it provides and it may shed some light on the incident.
2017-2-11
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tvl
lvl.4
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AlecW Posted at 2017-2-11 18:47
Upload a log to the link Labroides provided in post 3.  It has a lot more info. to help.

OK, here you go:

http://www.phantomhelp.com/LogViewer/7FMY48UJ2QGN3YEAON32/
2017-2-11
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tvl
lvl.4
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Nigelbrinkmann Posted at 2017-2-11 18:42
Hi, sorry to here about the crash,
Just a thought, did you have a gimbal guard fitted, this can cause the motors to stop if only the left stick was pulled right down 100% to desend.
Also as mentioned above, play back the flight records and enable the stick overlay and check if you did a CSC.

Nope, I always remove the guards. I have a warning label attached to them to remind me. However, I have never forgotten to remove either piece before flight!
2017-2-11
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tvl
lvl.4
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I'm using an iPhone 7 and would love to see the stick positions for this extremely short flight. It would set my mind at ease to know if I did make a mistake or not. I still have to believe I did NOT make a CSC error. So, how do I view the stick positions. I need a little more info other than what was in the one post above referring to an I Pad.
2017-2-11
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Mark The Droner
Captain
Flight distance : 2917 ft
United States
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You say the craft dropped at about 50 feet, but the log ends at 160 feet.  So it's hard to say what happened.  The voltage does seem to spike a bit at the end of the log, but apparently that's not related since the trouble didn't start until you descended an additional 110 feet.  But why did the log end at a height of 165 ft?  Could it be the craft actually fell from 165 feet?

Could it be the battery wasn't quite fully inserted?  

2017-2-11
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tvl
lvl.4
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tvl Posted at 2017-2-11 18:59
I'm using an iPhone 7 and would love to see the stick positions for this extremely short flight. It would set my mind at ease to know if I did make a mistake or not. I still have to believe I did NOT make a CSC error. So, how do I view the stick positions. I need a little more info other than what was in the one post above referring to an I Pad.

Hot dog, I found the flight log on my iPhone and played back the flight. It is remarkable how everything is logged! Anyway, here is what I observed:

1: The drone fell from a higher height than I thought. The flight log ends at 164 feet. So, I am assuming it fell this distance also!

2: The flight stick simulator shows without a doubt the right stick was not being used just before the unit powered off. Therefore, I'm hoping this rules out a CSC error on my part.

What is the next step? What can you guys see from the records? Can you folks also see the controller stick orientation during the flight?

UPDATE: I just went back and played through the short flight two more times. Again, this definitely wasn't a CSC error ......... at least according to the simulation that played with the control sticks being displayed!!!  Will my other flight records I posted tell you folks the real cause of the power failure? If not, then what should I expect out of DJI warranty. I'm still thinking that without concrete evidence for the power failure, I don't have a chance at getting this repaired under warranty. Or will the controller stick playback stand as proof that there was no CSC error on my part. And from there, I would have absolutely no idea what else could have cut power ............... at least not from operator error!
2017-2-11
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Nigelbrinkmann
First Officer
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Australia
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tvl Posted at 2017-2-11 18:59
I'm using an iPhone 7 and would love to see the stick positions for this extremely short flight. It would set my mind at ease to know if I did make a mistake or not. I still have to believe I did NOT make a CSC error. So, how do I view the stick positions. I need a little more info other than what was in the one post above referring to an I Pad.

On i Phone 7, open, dji app,go to the P4, top left press the triangle looking icon, tap on the flight, it will open as a map, then in your play bar at the bottom you will see the controller icon press it and the overlay will come onto your screen.
Edit, looks like you found it.
2017-2-11
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Labroides
Captain
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tvl Posted at 2017-2-11 18:53
OK, here you go:

http://www.phantomhelp.com/LogViewer/7FMY48UJ2QGN3YEAON32/

Thanks ... the most common cause of a Phantom dropping from the sky is flying with a partially charged battery,
Yours was fine and can be discounted as a factor as it had better than 4V in each cell at the end of the flight.
You had the throttle down and stable for the last 6 seconds with minor corrections with the rudder control.  The right stick stayed centred.
It's very unlikely that you used the RTH button at the same time.
DJI chose this combination because it's so unlikely to hit by accident.

The flight record just ends with no clues as to why.
This one looks like a case for DJI to investigate looking at the data from internal flight recorder.
2017-2-11
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tvl
lvl.4
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Labroides Posted at 2017-2-11 19:18
Thanks ... the most common cause of a Phantom dropping from the sky is flying with a partially charged battery,
Yours was fine and can be discounted as a factor as it had better than 4V in each cell at the end of the flight.
You had the throttle down and stable for the last 6 seconds with minor corrections with the rudder control.  The right stick stayed centred.

Well, I like your report! Not so much because it favors me, but because I continue to think this was not an accident. It was a very short flight .............. practically straight up and then back down. Everything was basically a "no brainer" - take her up, record a very brief segment, and bring her down. Soooo routine!!! And then a power loss??? I simply could not understand what was occurring! And still don't!

PS:  you stated:  "It's very unlikely that you used the RTH button at the same time"  -  

Absolutely not is the answer as you have implied! Why would I want to do that? And there again, how do I prove that I didn't? I don't want to get blamed for anything unless there is concrete evidence and I still honestly believe there was NO operator error involved today!
2017-2-11
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tvl
lvl.4
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To Mark the Droner:

I had estimated it fell from about 50 feet. Obviously that was not a good estimate. And for the way the gimbal was bent and the fact the housing assembly was damaged also, the fall was definitely from a height greater than 50 feet. Bottom Line:  my height estimate was terrible!

The battery was the first thing I checked before and after the incident. It was firmly locked in place before flight AND even after the fall it was still firmly in place!
2017-2-11
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tvl
lvl.4
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Well, unless someone else can shed some light on the cause, I guess I need to make arrangements to return the unit for repairs.

What is the process?    Primarily:

1- who do I need to contact?
2- where will it be shipped? overseas?
3- what is the general turn around period?
4- have most folks found the process to be honest & straight forward. In other words, if there is no clear & concrete reason for failure, the owner gets the benefit of doubt?
2017-2-11
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fansa84fe8a4
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tvl Posted at 2017-2-11 20:06
Well, unless someone else can shed some light on the cause, I guess I need to make arrangements to return the unit for repairs.

What is the process?    Primarily:

1. Start here:  https://www.dji.com/service/repair
2. Probably will go to Carson, CA if you are in USA.
3. 3-4 weeks average with shipping and your location.  Hopefully not a parts backorder wait.
4. Depends on their findings.

Good luck.  Maybe they will find a reason why and grant you a warranty.  However, you may get a refurb back too as that is their option (Along with a lot of consumer products warranty operations.) so be aware of that.
2017-2-11
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DJI Natalia
Super Moderator
Flight distance : 318 ft

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Sorry to hear about the crash and damage.
As mentioned above, you can submit it online for a case number and apply for a pickup if you're located in US: https://repair.dji.com/en/SelfRepair/Area
Our engineers will analyze the data and evaluate the aircraft, then let you know the details.
2017-2-11
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Cobrajet
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I agree, get it fixed.  Would be cheaper than starting over....

BTW, I know it's hard to prove but is there a chance the battery wasn't secured properly and worked its way out a few mm's?
2017-2-11
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Odan
Second Officer
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United States
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Great job of investigating dude. I'm impressed.   This looks like a very clean F/R.  No warnings  no errors
If it were my drone I'd be stumped too.
These things cost money to fly.  I learned that with Helicopters.  I did repairs at a shop and I can tell you
that good repairs aren't cheep.   I can tell you that I have spent nothing compared to Heli's  I regularly had labor fees up to $200.oo on the nicer lines of heli's.
Now if my drone need help...I'll let someone else do all the work.  That's one of the reasons I went for the DJI series.
I hope this goes in your favor,  good luck and keep flying   
I think we all look forward to seeing some great photos and vids from you....Drone on   
2017-2-11
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tvl
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Cobrajet Posted at 2017-2-11 20:47
BTW, I know it's hard to prove but is there a chance the battery wasn't secured properly and worked its way out a few mm's?

Well, as I mentioned in an earlier post, I checked the battery before flight and it was snug & locked in position. That was the first thing I checked when I picked up the unit after it hit the ground and once again I found the battery was snug and locked in position. So, I'm assuming the battery can  be ruled out unless there was another not so obvious battery issue.

And, as mentioned in my first post, after I cleaned up the unit and replaced the props, I flew the craft for a very short while up to an altitude of about 15 feet. Naturally, I had some errors and the camera was severely damaged, but it did fly ................. and that I do not understand! Earlier I had lost power and the craft fell to the ground and now it flies again?????  This makes no sense as I would not have expected it to do anything. Puzzling!!!!!!!

PS: I am editing this post as I just realized something after sending the response. I recall checking the battery after the unit fell to the ground as mentioned above BUT, I now also recall the battery was NOT on. At the time, that didn't get my attention possibly because I felt the hard hit had caused it to power off. Now, I am very curious??? Did the battery somehow power OFF during flight???????


2nd edit:  It's early and obvioulsy I'm not thinking very well! My edit indicated I found the battery in an OFF state after the crash. Well duh, I guess so. This is what this is all about!  A loss of power during flight. So, the battery should have been OFF when I checked it. Now, did the battery power itself off OR did something else cause it to power off. That is the question!

2017-2-12
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blackcrusader
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Well do as the DJI rep posted and send in the flight logs.  
Sorry to hear about your issue. Also do not fly the drones directly above you as you can have signal loss.

Very strange you seem to have had a complete power failure.  I've only been flying my drone 3 weeks.  Had one crash from a low height into a tea hedge from around 10m.
No damage the hedge was like a nice soft airbag and drone never hit the ground. Issue, I lost a prop as not screwed on tight enough.
Second crash my fault flew into a pole.  I had turned around to come home and of course when flying facing yourself the stick commands still work.
My brain fade I wanted to reverse away from the pole but hit the forward control.  Not very high up but some damage to the upper housing. Again my fault.

Today took my drone out for a flight with the Argtek Antenna installed and the latest 3.1.3 app and drone firmware. Everything smooth as for a round trip 12000 foot distance flight.

Hope your drone is fixed asap.   No idea how a battery could be turned off in flight as it has to be manually turned on by holding the button in, not once but twice.
2017-2-12
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Nigel_
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Looks like it shut down the motors because it thought it had landed, for the last 2 seconds it thought it only dropped 1m even though the throttle was on full down.

Just before the end, from 2m 51.9s to 2m 52.8s (1 full second) it drops by zero meters, so I think it thought that you had caught it in your hand and the last small movement was just you holding it.

So why did it stop dropping while still 50m above the ground when you had the throttle full down?

Was it very windy near a building and an updraft caught it?
More likely a barometer failure.
Did it appear to be having difficulty coming down?  Most of the full throttle down is nowhere near the 3.5m/s that it should achieve, and at times it is only 0.5m/s.  If it appeared to be descending normally then again barometer failure seems likely.

When you send it in, make sure they know it is a warrantee claim and not a repair and give a description of what happened, I guess you will receive a new one at no cost.

P.S. what aircraft is it?
2017-2-12
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Nigel_
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tvl Posted at 2017-2-11 19:41
I had estimated it fell from about 50 feet. Obviously that was not a good estimate. And for the way the gimbal was bent and the fact the housing assembly was damaged also, the fall was definitely from a height greater than 50 feet. Bottom Line:  my height estimate was terrible!


The log says it was still at 164.4ft, maybe this confirms a barometer failure and it was actually close to 50ft as you thought?
2017-2-12
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s0
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Looking at the bottom of the logs, it seems the engines cut out at 165.4ft. http://www.phantomhelp.com/LogViewer/7FMY48UJ2QGN3YEAON32/

But that log also shows (first message at the top of the log) that home point altitude was set to 50m (=164ft...)!!!

Do you see where I'm going with this? It had reached its home point altitude, and its descent had paused (perhaps a small updraft), so it cut the motors just as it was supposed to do!!!

How can home point altitude ever be anything other than zero, unless a home point was set while in the air (and in this case the log shows it had not yet taken off).

This is not pilot error.

Looks like you are using P4/iOS DJI 4.0.3. That seems like a software bug (setting home point altitude to 50m, when P4 on the ground and not yet taken off). I hope Android DJI GO4 4.02 is OK, as that is what I have!







2017-2-12
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Mark The Droner
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Can you tell us the approx air temp?  
2017-2-12
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Nigel_
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s0 Posted at 2017-2-12 05:00
Looking at the bottom of the logs, it seems the engines cut out at 165.4ft. http://www.phantomhelp.com/LogViewer/7FMY48UJ2QGN3YEAON32/

But that log also shows (first message at the top of the log) that home point altitude was set to 50m (=164ft...)!!!

That is the "RTH Altitude", which seems reasonable, the measured altitude starts at zero as expected.
2017-2-12
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tvl
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sO stated:  "But that log also shows (first message at the top of the log) that home point altitude was set to 50m (=164ft...)!!!"

I will need to look into this further after church. I am new to all of this (less than 3 weeks) and am learning quickly about all of the diagnostic tools and flight records.

If the takeoff altitude was set at 50 meters as you stated, what on Earth would cause that. This is done automatically, correct??????

I have roughly 3 hours on the craft and until yesterday, I had encountered absolutely no issues whatsoever.

Would someone else please take a look at the flight record and see if you would agree with the statement above?
2017-2-12
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tvl
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Mark The Droner Posted at 2017-2-12 05:11
Can you tell us the approx air temp?

It was approximately 70 degrees at the time.
2017-2-12
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Labroides
Captain
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s0 Posted at 2017-2-12 05:00
Looking at the bottom of the logs, it seems the engines cut out at 165.4ft. http://www.phantomhelp.com/LogViewer/7FMY48UJ2QGN3YEAON32/

But that log also shows (first message at the top of the log) that home point altitude was set to 50m (=164ft...)!!!

"But that log also shows (first message at the top of the log) that home point altitude was set to 50m (=164ft...)!!!
Do you see where I'm going with this? "
The recorded home point never has any altitude associated with it.
It's just a lat/long position.

The message you misread says:  Home Point Set; Home Point Recorded. RTH Altitude:  50m.
2017-2-12
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s0
Second Officer
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Whoops, cancel that idea then!
2017-2-12
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Nigel_
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WindSoul Posted at 2017-2-11 15:33
I have myself started a poll as to see how people feel about a dedicated switch for start/stop motors. I still believe is important DJI implemented a foolproof method rather than use flight sticks. You may want to visit the poll (on Phantom 4) and contribute with your vote.


I think maybe what is needed is for DJI to check the accelerometers as the motors come to a stop and if they show a 1G downwards acceleration then restart them immediately!  Needs to be done quickly and maybe only at half power until the throttle is pushed up, otherwise hand catching would become dangerous, but an issue with a single barometric sensor shouldn't cause the aircraft to fall out of the sky at high speed.  Also maybe a mid air CSC would be safer for everything below and the aircraft if it only removed half the power while falling.

Of course power off is probably a lot more complex than just trusting a single sensor so maybe this isn't valid.
2017-2-12
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Aardvark
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Flight distance : 384432 ft
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tvl Posted at 2017-2-11 19:31
Well, I like your report! Not so much because it favors me, but because I continue to think this was not an accident. It was a very short flight .............. practically straight up and then back down. Everything was basically a "no brainer" - take her up, record a very brief segment, and bring her down. Soooo routine!!! And then a power loss??? I simply could not understand what was occurring! And still don't!

PS:  you stated:  "It's very unlikely that you used the RTH button at the same time"  -  

Sorry to hear about your crash, I can't see anything to indicate 'pilot error' in the records you posted. DJI should be able to analyse the file you sent them and perhaps give a reason.

Just to clarify on the motor shut down procedure on a P4 :-

A CSC (Combination Stick Command) involves pushing both sticks fully down and both fully towards centre, or away from centre of RC unit. On a Phantom 4 this will not cause the motors to shut down while in flight. This CSC is used to start or stop the motors when the P4 is stationary on the ground.
Pulling the left stick full down on a P4 while in flight will not cause the motors to shut down.
Pulling  the left stick full down and operating the RTH button on a P4 will not cause the motors to shut down.
Pulling left stick full down and partially to centre and operating the RTH button will not shut down the motors on a P4.
The only thing that will shut down the motors on a P4, as stated in the manual, and can be tested in the flight simulator, is to hold left stick fully down and fully centred (half way between the 3 O'clock and 6 O'clock position) and press the RTH button (the RC also begins 'beeping' rapidly to indicate shutdown command).

Edit:- the above of course 'assumes' that the controller is operting in the default 'Control Stick Mode of Mode 2'. No reason to assume otherwise.
2017-2-12
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