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Close Call due to Auto Landing above water (video)
469 23 2017-9-12 02:36:03
ShaggyDuck
lvl.1
United States
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Hi all. Looking for any reason my Spark would auto land as seen in the video. Battery was at 17%.
Any help will be much appreciatied.



And here is the Flight Record
http://www.phantomhelp.com/LogViewer/X5WUUY4GSGQKSNO6EDDY/#

2017-9-12 02:36:03
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jksphoto
lvl.4
Flight distance : 12290
Sweden
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I wouldn't still be flying at 17%, usually bring it back at 30%. Good save though, some quick reactions right there.
2017-9-12 02:42:34
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DJI Elektra
Administrator
China
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ShaggyDuck,sorry for you lost, please contact our support and start a case: http://www.dji.com/support
Did you get any reminder from your app that the electricity amount is too low? Auto landing may cause by the electricity amount. If you have doubt about your accident, you can provide your flight data to our support and ask for analysis. Thanks.
2017-9-12 03:22:26
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Wachtberger
lvl.3
Flight distance : 17517
Germany
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Difficult to say what precisely has happened. The flight log viewer from phantomhelp is not reading all messages in the Spark flightlogs and thus is incomplete and not reliable. Had you not been in sport mode, my guess would have been that the tree branches the Spark was heading to made the obstacle avoidance system stop him and land at the point where he was. But this is not activated in sport mode...
2017-9-12 03:22:00
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El Diablo
lvl.2
Germany
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Wachtberger Posted at 2017-9-12 03:22
Difficult to say what precisely has happened. The flight log viewer from phantomhelp is not reading all messages in the Spark flightlogs and thus is incomplete and not reliable. Had you not been in sport mode, my guess would have been that the tree branches the Spark was heading to made the obstacle avoidance system stop him and land at the point where he was. But this is not activated in sport mode...

What has that to do with autolanding at 17%??? It is not in a critical stage yet? Mine did exactly the same in Madeira while flying over the sea at low altitude. I never pushed the stick down nor pressed any "want to land?" botton... Dji has to get the Spark's fw working before people is going to start calling their lawyers...
2017-9-12 03:47:17
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ShaggyDuck
lvl.1
United States
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jksphoto Posted at 2017-9-12 02:42
I wouldn't still be flying at 17%, usually bring it back at 30%. Good save though, some quick reactions right there.

Thanks, I don't really know how I got to it so quick. Quick reactions and long legs saved her i do have three minor flesh wounds from the blades but my bird still flies!
2017-9-12 04:37:34
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ShaggyDuck
lvl.1
United States
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DJI Elektra Posted at 2017-9-12 03:22
ShaggyDuck,sorry for you lost, please contact our support and start a case: http://www.dji.com/support
Did you get any reminder from your app that the electricity amount is too low? Auto landing may cause by the electricity amount. If you have doubt about your accident, you can provide your flight data to our support and ask for analysis. Thanks.

Ok, will do as soon as possible.
2017-9-12 04:42:37
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ShaggyDuck
lvl.1
United States
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DJI Elektra Posted at 2017-9-12 03:22
ShaggyDuck,sorry for you lost, please contact our support and start a case: http://www.dji.com/support
Did you get any reminder from your app that the electricity amount is too low? Auto landing may cause by the electricity amount. If you have doubt about your accident, you can provide your flight data to our support and ask for analysis. Thanks.

Please provide an email address to send the files to. I cannot find it on the website.
2017-9-12 04:57:02
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Montfrooij
First Officer
Netherlands
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You were (sort of) lucky.
2017-9-12 05:23:17
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Charles Adams
Second Officer
Flight distance : 61878
United States
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Whenever there is something presented in the forums that I don't understand, I like to experiment and practice.  In this case, I am too afraid to practice this over water (which may or may not have played a role given the visual positioning system).

The flight log you have posted doesn't seem to include the first 9 minutes of flight (or I do not know how to access the first nine minutes).  It is possible that you took off from safe ground, flew slightly forward over the water, and it is at this point where either you selected home point or the craft auto set home point (over the water).  That's a guess without additional data.

There is an option in the app to abort the RTH feature from executing and the auto-landing feature from executing.  The terror of seeing my drone trying to land on water may have caused me to panic, but I've practiced this maneuver enough to where I THINK what I would have done is observe that the landing location was unsuitable, cancel the maneuver on the app, and manually fly to a more suitable location.

I like to practice these maneuvers ahead of time so that in the case I'm faced with circumstances that are unusual (or terrifying) I have some experience on addressing it.
2017-9-12 05:59:37
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Sparkylicious
lvl.2
Flight distance : 12892
United States
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That spark seems to move erratically, as if its on ATTI mode. Lost GPS perhaps and his flying it attitude mode?
2017-9-12 10:12:14
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DJI Elektra
Administrator
Japan
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ShaggyDuck Posted at 2017-9-12 04:57
Please provide an email address to send the files to. I cannot find it on the website.

Shaggy, please provide me the case number after you start a case. Then you can upload it to dropbox and post here. Thanks.
2017-9-12 18:11:21
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SparkPete
lvl.2
Flight distance : 25558
Germany
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Watching the video and looking at your log it looked like:

Battery was low enough that Spark will start RTH in 10 seconds (you can hear this in the video).
You flew it close to the home point so RTH switched to auto landing (you find this in the log).
Spark started auto landing.

To this point everything worked as expected.

Spark now should have descended and hover 0.3 m above the ground but instead it was about to dive into the water.
Seems Spark did not detect the "ground level" aka water surface correctly. Why? I don't know, that is something DJI has to investigate.

For me there are 2 things to learn:
1.) Keep in mind that the Spark does not land at the home point, if it is already near the home point when RTH triggers. This is normally not an issue but can be, if there is water or other dangerous surface near the home point.
2.) Don't rely on auto landing when the Spark is over water or other surfaces that might throw-off the VPS. Instead land manually with the sticks.

@DJI: Maybe give an option to suppress RTH and auto landing BEFORE it actually triggers, like during the 10 second count down. As this accident shows, there is very little time to react after auto landing kicked in.
2017-9-13 08:49:45
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Sparky_17
Second Officer
Flight distance : 8415
Canada
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still flying with 17& battery left is not a good idea .. good recovery
2017-9-13 09:56:38
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Kloo Gee
lvl.3
Flight distance : 129384
United States
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Based on my experience, my assumption is that you have the "RTH at Current Altitude" option disabled and the Spark very likely behaved exactly as documented.

As can be heard in the video, the voice tells you that the battery is low and that it will initiate an RTH in 10 seconds.  10 seconds after that verbal warning was provided (and I'm assuming also shown on DJI Go screen), it initiated the RTH procedure without you cancelling it.

Looking at your log files you posted on PhantomHelp, you were 19.2 feet away from the home point and somewhere between 14 feet (VPS)  and 20 feet (IMU) high.  

From pg 14 of the manual (https://dl.djicdn.com/downloads/Spark/20170727/Spark+User+Manual+V1.4.pdf):
"When the aircraft is between 3m and 20m from the Home point, it will land automatically with the RTH at Current Altitude option disabled.  The aircraft will return to Home Point at the current altitude with the RTH at Current Altitude option enabled if flying at or above 2.5 m, and iw will ascend to 2.5 m then return to hom if flying lower than 2.5 m when the aircraft is between 3 m and 20 m from the Home Point."

As mentioned, your logs show you were 19.2 feet away from the home point, this is definitely between 3m and 20m from the Home Point, so it tried to land automatically.
Had the Spark been over solid ground at the point it decended, it would have stopped at 0.3 m above the ground and hovered waiting for you to confirm for it to land or do something else.  However, given you were over water, its sensors may not have been able to accurately determine its height above the water, so it may or may not have sat at 0.3 m and hovered.  It looks like you "rescued" it before being able to see if it indeed would hover at 0.3 m or not.

*EDIT1:  Edited for terrible typos and ommissions.
*EDIT2: Interesting time for this to pop up, I actually have a video recorded about RTH features that I am editing and hope to publish late today or tomorrow that goes through the different scenarios of the RTH procedure.
2017-9-13 10:28:36
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Sparky_17
Second Officer
Flight distance : 8415
Canada
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That was close ...
2017-9-13 10:40:03
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larrymull
lvl.2
Flight distance : 47975
Australia
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Good result in the end, 17% is risking it a little I must say.
2017-9-13 15:02:21
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brian_b
lvl.2
United States
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Would update RTH point, to the remote, have helped? To get inside that 3-20m and away from the water?
2017-9-13 15:41:16
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Mark S
lvl.2
Flight distance : 9666
United States
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I agree, as a few said here, they would not fly over water.  The risk of loss is much higher and a crash likely to be more damaging.

Relying on RTH to be VERY accurate could also be a problem.  If you read about GPS accuracy it could be plus or minus a few meters.  That could be the difference in landing on shore or on water or on a road surface or on the side of the road.  There also can be a reflected signal problem as show in the link.  I would have not guess this could happen.  I wonder if water can reflect the signal?

http://www.gps.gov/systems/gps/performance/accuracy/
2017-9-13 17:35:58
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Kloo Gee
lvl.3
Flight distance : 129384
United States
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SparkPete Posted at 2017-9-13 08:49
Watching the video and looking at your log it looked like:

Battery was low enough that Spark will start RTH in 10 seconds (you can hear this in the video).

Looks like you and I provided the same explanation using different words.  

I have reviewed the video multiple times and using YouTube's ability to slow the speed of the video down to 0.25 or 0.5 speed, I believe that the Spark did indeed stop to hover at 0.5 m above the water.  If you watch the video in slow motion starting from the 0:10 second mark, you will see that it accelerates its downward motion, then gets close to the surface of the water, it slows down and does a turn right before the user jumps in the water to rescue it.  

Based on that, I think it behaved exactly as documented and had the user not jumped in the water, it would have hovered at 0.5 m waiting for further directions.

Having said that, there's a good chance I likely would have jumped in to save it as well!  Lol!

My take away from this is to not let the battery get so low before initiating a landing (especially over water) and to take control of the Spark before the RTH gets initiated in such close proximity.

Glad everything turned out well and the Spark didn't go for a swim!
2017-9-13 18:18:28
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ShaggyDuck
lvl.1
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Thanks all for the replies, I am still a novice and am learning a lot from this experience.

My friend was flying at the time, I heard the RTH voice prompt, reached over and pressed the red pause bottom. This I thought would have cancelled the RTH.

Also, it stated RTH would initiate in 10 seconds- in my mind we had plenty of time to at least get it over the handrail and safe before then. Instead it seems to me it saw it was close to home and bypassed the 10sec count down to auto land. If I'm correct this seems like a big software mistake.

When I caught it was WAY to close to the water for comfort!
2017-9-13 22:58:03
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ShaggyDuck
lvl.1
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Working two jobs doesn't allow me much spare time but I have opened a case with DJI and will post the results here asap.
2017-9-13 23:02:49
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DJI Elektra
Administrator
Japan
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ShaggyDuck Posted at 2017-9-13 23:02
Working two jobs doesn't allow me much spare time but I have opened a case with DJI and will post the results here asap.

Thanks for your support. You can also PM me your case number and the data.
I believe that the support will do their best to help you solve the problems.
2017-9-14 01:06:37
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Kloo Gee
lvl.3
Flight distance : 129384
United States
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ShaggyDuck Posted at 2017-9-13 22:58
Thanks all for the replies, I am still a novice and am learning a lot from this experience.

My friend was flying at the time, I heard the RTH voice prompt, reached over and pressed the red pause bottom. This I thought would have cancelled the RTH.

You can see in your video, it is exactly 10 seconds after the warning starts that the automatic landing initiates.  

I probably would have jumped in to try to save it as well.  Too much money to be trusting it to do the right thing in that scenario!  Great reflexes!
2017-9-14 07:14:15
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