RTH failsafe
6128 10 2020-3-2
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Cryptic
lvl.4
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United States
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So I get the general understanding of how this feature works but I just want to be sure. So if the controller loses connection for more than 3 sec it will begin the FailSafe RTH function. So say the battery on my controller dies the drone will comeback to me? The other one is that if it is to far away and has very little battery left it will land. I just want to know so that if it happens to me I can have peace of mind. Thanks!
2020-3-2
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hallmark007
Captain
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Yes you have it right, not a good idea to let battery run down so much that you can’t get home, so set correct parameters before you fly.

If you want to test, fly out more than 20m turn off RC and watch it return home .
2020-3-2
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Cetacean
First Officer
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Aloha Cryptic,

     The 3 second communication loss is basically if you fly around an object or structure that blocks your transmission.  Once the bird returns to line of sight, transmission is usually restored and you can get control back again.  But make sure that your RTH Safe Altitude is higher than the object or structure because your drone can and will sometimes fly into the object or structure.

     If the battery on your controller dies, you usually were really not flying safely because you did not charge the controller, but that is not saying it could not happen, but is also a good reason to keep your controller at two lights, even if one is flashing.  However, a different example is if your cable disconnects or you accidentally turn off the remote controller.  The drone will return to the recorded GPS location of the display or device for take-off.  The Remote Controller does not have GPS unless you are flying a Plus with a built-in display.

     Now if you fly too far away, the Intelligent Battery will be warning you way before you run out of battery.  You should really listen to those warnings.  First thought should be, "What direction is the wind and how strong is it?"  Then make your decision.  

     Now a recent problem has been some batteries have been having cell issues.  This can be cold, swelling, age or manufacturer defect somehow.  Also, flying on a battery with less than 90% can give you that problem.  You will be warned that the drone is landing.  In this case, you can usually push the left stick up to halt the descent.  This happened to me a few months ago (old and swollen battery) and I was able to land in my friends yard a half mile away.  (Then I had to wash my pants.)

     These are all preventable situations so it is good that you are thinking ahead about it.  Also, some people on the Forum use RTH to fly home.  Not a bad idea and it can allow you to relax and just observe the flight and maybe look into other issues and possibilities.  For example, RTH and then take control to divert to another site or do a maneuver of some sort.  

     Remember though that you can descend with the stick during the RTH but I think you cannot ascend.  So do not descend below the set safe altitude.  I have used RTH to record video in a manner similar to CourseLock.  Mostly, you need to experiment and see what the possibilities are.  But, RTH is very helpful and a great safety feature.

     Hope this helps!

Aloha and Drone On!
2020-3-2
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DJI Stephen
DJI team
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Hello and good day Cryptic. The DJI Mavic Mini supports Smart RTH, and the aircraft can return to the Home Point automatically. Here are the logic, operation, process, and notices of the Smart RTH function.

Set a reasonable RTH altitude :
Before the flight, go to “Safety” and set the RTH altitude higher than that of the tallest building in the surrounding area. Users can set the RTH altitude from 15 m to the max flight altitude.

Logic of Smart RTH:
When the Home Point is recorded and the distance between the aircraft and Home Point is more than 20 meters, users can tap the icon shown on the left of DJI Fly to choose to land or initiate RTH. Press and hold the RTH button on DJI Fly, or press and hold the RTH button on the top left of the remote controller to initiate RTH. The remote controller will make beeping sounds(after the RTH triggered,can short press RTH button to stop the beeping sounds, the return will stop too.). When the GPS signal is strong, the aircraft will return to home.
Note: If the GPS signal is weak, the aircraft will hover ( if the GPS signal does not get stronger, the aircraft will hover for three seconds to prevent itself from drifting because of the poor GPS signal ), and then the aircraft will land. If the distance between the aircraft and Home Point is less than 20 meters, after users press the icon on the left of DJI Fly, only the landing option is available.

Smart RTH Process :
If the aircraft’s current altitude is lower than the RTH altitude that has been set before, then the aircraft will rise from its current altitude to the previously set RTH altitude ( when the aircraft is rising, users can pull the control stick to make the aircraft stop rising, and then the aircraft will return to the Home Point at the current altitude ). Then the aircraft will return to the Home Point along a straight line. If the aircraft’s current altitude is higher than the RTH altitude that was previously set, then the aircraft will return to the Home Point along a straight line at the current altitude ( the left and right control sticks ,yaw axis are controllable, the roll axis are not controllable ). After the aircraft returns to the position above the Home Point, it will land onto the ground automatically and stop the motors.
Note: Compared to other Mavic aircraft, the Mavic Mini’s aircraft rising logic during RTH has changed. The aircraft’s throttle control stick is still controllable when the aircraft is rising and its altitude is lower than 20 meters.

Notices for RTH and Stopping RTH :
Please always pay attention to the aircraft flight screen image and aircraft position during the RTH to make sure the aircraft is safe. If something goes wrong, users can press the “X” icon on the left of DJI Fly, or press the RTH button on the top left of the remote controller to cancel RTH. After the RTH is canceled, the aircraft will hover at its current position. In this case, you can control the aircraft manually. Please fly carefully and do not initiate RTH again until the aircraft is in a safe environment.

Thank you.
2020-3-2
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m80116
lvl.4
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Italy
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It must be noticed that unplugging a cable does not trigger any RTH as long as the RC remains on and connected with the AC.
2020-3-2
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GaryDoug
Second Officer
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Huh. I thought the time was 11 seconds of lost comms before failsafe RTH was initiated. Did I miss something in the manual?
2020-3-2
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JJB*
Core User of DJI
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GaryDoug Posted at 3-2 20:24
Huh. I thought the time was 11 seconds of lost comms before failsafe RTH was initiated. Did I miss something in the manual?

11 secs for the MM, 3 for MA (and others, check their manual)

2020-3-2
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hallmark007
Captain
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Low battery 10sec
Failsafe 11sec
Rth hold 3sec

Can be confusing for beginner particularly when you see other drones with different values.
2020-3-3
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Guorium
lvl.4
Flight distance : 513061 ft
Australia
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Apart from the discussion, quick tips for you. If you push forward during rth (provided you have controller connection still, the video may not be present) you can reach S mode speed ~13m/s even if you were in P mode before RTH. That can get you out of a windy situation safely. However, if the controller is not connected at all you obviously cannot send the stick command to the drone so it will keep the automatic top speed of 8m/s. That may not be enough if it was already getting blown away on a windy day.
2020-3-3
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GaryDoug
Second Officer
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JJB* Posted at 3-2 22:59
11 secs for the MM, 3 for MA (and others, check their manual)

OK, but this is a MM forum and the OP has a MM.
2020-3-3
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hallmark007
Captain
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GaryDoug Posted at 3-3 11:05
OK, but this is a MM forum and the OP has a MM.

Yes and the Mavic air failsafe is.
20 sec phone
10 sec wait for retrace
3 sec loss remote signal
2020-3-3
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