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loss of control (remote controller) during RTH?
2215 11 2017-11-8
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krisp-spark
Second Officer
Australia
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Hi all,

I am new to drones and bought mine just recently (spark fly more combo). I did only 29 flights and 2hrs 12 minutes in total.
Today when I was flying and when the battery level dropped I decided to return. At this stage, the drone was not far from me, only 38.2 meters, the battery was at 18%, 2:28 mins remaining, so I started navigating back to me. After 8 seconds I got a message "Tips: Low Power. Aircraft is returning to the Home Point." At this stage, the battery was still at 18% (all this info is from Flight Records in the app). And it was at this point when the aircraft started ascending, and because the aircraft was ascending directly to a tree, I wanted to avoid a collision by putting the throttle down, but nothing happened, the drone was still climbing.

From the moment I decided to return and land, I didn't look at my phone screen because the aircraft was in a line of sight and I was maneuvering to avoid trees and bushes. When the aircraft was not responding to my remote control input, I checked phone screen, where I could see "stop" button (red circle with X on the left of the screen). When I tapped that icon, nothing happened (maybe momentary phone issue?). So I started panicking because I could see my drone climbing into the tree and could do nothing about it. After two or three seconds the drone hit the first branch, and because of the sudden loss of revs it dropped few meters (one or two), then stabilized and then started climbing again, and again hit the branch with leaves and again dropped lower. After that, the drone started responding to my remote control, however, it still wanted to climb and fly towards home point. It was really difficult to catch the drone with one hand while holding the throttle down with the other hand and running behind it. Must've been funny to watch if anyone saw me.

Luckily, no damage to the drone, there are just a few marks on the propellers from chopping the leaves.

My question is:
1. Is there something weird about what happened to me today? Or was the drone just climbing to predefined RTH altitude? Is there option to disable automatic RTH in case of low power?
2. How exactly does the RTH work and why it was triggered automatically?
3. What can I do to cancel it in case my phone stops responding? Just press the button on the remote control? And what would you do if you don't have a remote control, aircrafts goes into RTH automatically and your phone freezes?

Thanks and sorry for such a long text, but this event freaked me out a bit.
2017-11-8
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S-e-ven
Captain
Flight distance : 5910961 ft
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Thailand
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Usually you can cancel everything, except the "critical battery, landing now"
Which I do mostly, anyway.
Have you missed the "cancel" option on that "going to Homepoint" message?
2017-11-8
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DJI Elektra
DJI team
Hong Kong
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Here are some answers toward your questions:
1.You can cancel the RTH to regain control of your drone.
2.It will be triggered when your drone lost wireless signal for some times.
3.Please note that there are three RTH procedures and you can read our manual to know about how to exit different modes of RTH. (Page 13)

2017-11-9
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S-e-ven
Captain
Flight distance : 5910961 ft
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Thailand
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DJI Elektra Posted at 2017-11-9 02:55
Here are some answers toward your questions:
1.You can cancel the RTH to regain control of your drone.
2.It will be triggered when your drone lost GPS signal for some times.

"2.It will be triggered when your drone lost GPS signal for some times."

It will be triggered when your drone lost RC signal for some times.
Without GPS, it is switching into "drift away" atti mode, isn't it?
2017-11-9
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DJI Elektra
DJI team
Hong Kong
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S-e-ven Posted at 2017-11-9 03:08
"2.It will be triggered when your drone lost GPS signal for some times."

It will be triggered when your drone lost RC signal for some times.

Sorry, it should be wireless signal. If the GPS signal is weak, it can not return to home.
2017-11-9
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krisp-spark
Second Officer
Australia
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S-e-ven Posted at 2017-11-8 20:33
Usually you can cancel everything, except the "critical battery, landing now"
Which I do mostly, anyway.
Have you missed the "cancel" option on that "going to Homepoint" message?

I noticed the Cancel option on phone display after a while, but still, I couldn't tap it.
But still don't understand why I couldn't overwrite the RTH function with my remote control.
2017-11-9
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Flip_L
lvl.4
Flight distance : 330686 ft
Germany
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hitting either the pause button on your control or the X button on your phone should have stopped RTH immediately. I used it many times e.g. when RTH was initiated due to connection loss after I regained connection to fly back manually.
2017-11-9
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hallmark007
Captain
Flight distance : 9812789 ft
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Ireland
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You could put up your flight log to link below, just click on link and follow instructions come back here and post your link. It might give you a better understanding of what happened.

http://www.phantomhelp.com/LogViewer/Upload/
2017-11-9
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Kloo Gee
Captain
Flight distance : 16641309 ft
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United States
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"2. How exactly does the RTH work and why it was triggered automatically? "

As DJI Electra mentions, the manual has some good information about how RTH works.  However, for me, it didn't really sink in until I did some testing for a video I created.  

Check out the video and I think it will help you understand what you read in the manual a bit more clearly.


2017-11-9
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Gunship9
Captain
United States
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I want to know about low battery flight modes.  At 18 percent it seemed the aircraft was done with the pilot's shenanigans and headed back to land.
2017-11-9
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nixuspix
Captain
Flight distance : 2864974 ft
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Latvia
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Kloo Gee Posted at 2017-11-9 05:26
"2. How exactly does the RTH work and why it was triggered automatically? "

As DJI Electra mentions, the manual has some good information about how RTH works.  However, for me, it didn't really sink in until I did some testing for a video I created.  

Really very comprehensive and useful video. Thank You Kloo Gee!
2017-11-9
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krisp-spark
Second Officer
Australia
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Thank you all for replies. I was reading the manual prior to first flight but the RTH wasn't still very clear to me. I guess the best would be to go somewhere open without obstacles and try the RTH mode to see what it does.

And another question comes to my mind: If the connection is lost for more than 3 seconds (with RC) then the AC will go to Failsafe RTH mode; if there are trees above the drone, it will just happily climb into those trees and nothing will stop it, right? Unless the connection is re-established.

Here is the log from this flight:
http://www.phantomhelp.com/LogViewer/AXWV7Q4H58PL6FO8R5D0/
2017-11-9
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