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Last 2 min of Flying'Bryan flight
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4498 52 2016-3-31
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pi-inthesky
First Officer
Flight distance : 13058 ft
United Kingdom
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terrylewis Posted at 2016-4-2 05:47
Now that this thread has mellowed, for anyone returning to this thread,
   I'd like to add some addi ...

Got to respect your ability to analyse flight logs TO SUCH AN EXTENT WELL DONE
2016-4-2
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Donnie
Captain
Flight distance : 3636782 ft
United States
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terrylewis Posted at 2016-4-1 23:47
Now that this thread has mellowed, for anyone returning to this thread,
   I'd like to add some addi ...

Terry You are indeed a great asset to this forum,  Although I did not say this near as eloquently as you ,I totally agree  and stated this early on during the debate., having both Apps running can cause the perfect storm .

Thanks again for all you do -  brother donnie
2016-4-2
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terrylewis
Captain
Flight distance : 3517287 ft
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davidson_g Posted at 2016-4-2 16:10
Very interesting analysis. If it were a case of the craft receiving autonomous course correction c ...

Thank you these excellent points! I agree that there is ample room for DJI to look at these interactions in light of the CSC changes/methodology recently introduced and their impact on SDK-based functions. Hopefully, we can all derive some benefit from this unfortunate flight.
2016-4-2
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Visual Air
Captain
Flight distance : 2710115 ft
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Canada
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DJI-Ken Posted at 2016-4-1 09:37
Bryan, You were flying with Litchi in POI mode, The DJI wasn't even being used for flying while you ...

100% left stick bottom right corner and 100% right stick top left corner this causes CSC ?
Is this right as i thought the right stick would have to be right stick bottom left corner and left stick bottom right corner to cause CSC?
This is becoming a bit convoluted to say the least can you clarify please.
2016-4-3
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DJI-Ken
DJI team
Flight distance : 1515312 ft
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Visual Air Posted at 2016-4-3 22:48
100% left stick bottom right corner and 100% right stick top left corner this causes CSC ?
Is this ...

Bryan was not using the GO app, it was running in the background. He was using the Litchi app  for a POI. The analysis data showed a CSC was done, the flight record form the GO app showed a CSC. The GO app went into low battery RTH and probably the Litchi app tried to keep the POI flight going. BUT ALSO, Bryan took off with 23% battey left to go do a POI mission. If he would have not taken off again with that low of a battery, maybe the GO app wouldn't have gone into low battery RTH mode.
So you should not be using two apps at the same time.From what Terry stated:
Lessons Learned:
  Pilots must maintain situational awareness by maintaining control of their aircraft, scanning the GO App for battery levels, alert messages, and take controlling actions when necessary. I believe that running both the GO App and Litchi contributed to this crash. I think taking off with only 23.9% battery also contributed to this accident. If Bryan says that he never touched the controls, then likely the two programs were fighting for control and flew the aircraft into autonomous CSC stick commands. Regardless, the motors shutdown because of a commanded CSC.

2016-4-3
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Mike_fnq
Second Officer
Flight distance : 5623 ft
Australia
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DJI-Ken Posted at 2016-4-4 01:14
Bryan was not using the GO app, it was running in the background. He was using the Litchi app  for  ...

Ken with respect
it is ONLY commanded if he executed the commands. which he states he did not (and we all believe him on this). Yes, he may have made some less than optimal decisions that contributed, but commanding a CSC wasn't one of them. That is likely to be a software conflict issue.
2016-4-3
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DJI-Ken
DJI team
Flight distance : 1515312 ft
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Mike_fnq Posted at 2016-4-4 07:24
Ken with respect
it is ONLY commanded if he executed the commands. which he states he did not (and ...

I did not say he manually did a CSC, It seems to have happened because he took off with 23% battery left and during his Litchi POI it went into low battery RTH and since both apps were running at the same time it caused the crash.
2016-4-3
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FAS1
Second Officer

United States
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How is it possible to even run two apps at the same time?
2016-4-4
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AG0N-Gary
Captain
Flight distance : 700846 ft
United States
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There's a problem with terminology, Ken.  DJI is saying commanded, when pilots/FAA/etc., consider commanded to mean the physical inputting to the controls.  This appears to be conflicting software inputs that created the problem.  Saying commanded makes it sound like FB pulled the sticks and said crash baby, crash!

Thank you TERRY for that excellent write-up.  I don't know what your day job is, but you're an asset.
2016-4-5
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microcyb
First Officer
Flight distance : 1095955 ft
United States
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FAS1 Posted at 2016-4-5 00:43
How is it possible to even run two apps at the same time?

Sadly they do run in the background and many apps also try to run as a service to keep internet connections going to pull data such as advertisements.
2016-4-5
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microcyb
First Officer
Flight distance : 1095955 ft
United States
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DJI-Ken Posted at 2016-4-3 22:56
I did not say he manually did a CSC, It seems to have happened because he took off with 23% batter ...

Well, that is a flaw that should be communicated to the Litchi team as well as the DJI Go team.  Sadly, I doubt tests will be performed by either side, till more users report issues of the CSC or malfunction like this occurs more often.
A correction to the DJI SDK for Active Session application check could resolve this problem.
2016-4-5
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Morph1
Banned

Canada
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Tip: the author has been banned or deleted automatically shield
2016-4-5
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teedo757
lvl.4
Flight distance : 1870 ft
United States
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Well I always thought that an iOS app had to go into suspension mode when put in the background but after a quick Google search it appears my assumption was wrong. Looks like it is not mandatory for an app to pause when it is sent to the background. Take a look: https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/BackgroundExecution/BackgroundExecution.html
2016-4-5
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