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  1. Kaitlyn

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    With the P4 having the front vision sensors and able to use those during RTH, why does it matter what the height setting is for RTH, since it will be able to avoid obstacles regardless?
     
  2. msinger

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    It matters because the front sensors are not able to see all obstacles (e.g. power lines).

    IMHO, you should always set your RTH altitude at least 50 feet higher than the tallest known obstacle since the altitude is only an estimate based off of data retrieved from the barometer.
     
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  3. jbrown630

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    ^ This
     
  4. Teo Morabito

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    And don't forget that you can adjust the height mid flight if you see a new obstacle


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  5. daveleeds

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    Also, in a case like this - the p4 might spend valuable battery life trying to find a way around obstacles instead of just going straight up out of the way.


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  6. coco777

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    The RTH height should be re-evaluated for each flight.

    People need to really think about each flight before they set the RTH height, and ask yourself this question first.

    What is the highest elevation of land (hill) I will be flying over for this flight ?

    If your home point is zero elevation, and the highest hill you will be flying over is 70 metres, and on that hill are trees at a max height of 20 metres, then you will need a RTH of at least 90 meters to clear the trees on the hill if RTH is triggered.
     
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  7. apex1

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    I just always set mine to 150m. Better safe than sorry.
     
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  8. John Locke

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    Yes, since a rarely have RTH enabled, I leave mine at 120M (400') since it's practically impossible to estimate how high anything is when looking at it from a half mile away. I rarely go behind anything anyway, since that's a recipe for auto RTH. On a long distance flight I will sometimes turn the craft to look at my launch site to make sure I'm still LOS, when I'm not sure.
     
  9. Pogopilot

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    What the other responders have not taken into account is the fact that the RTH height is based on your take off point. This is very important. While as Msinger says, you should set your height above tallest object, if that object is sitting on a hill that is 51 feet above take off point, you have lost your bird. Take the highest object + the height (that object is) above take off point + 20% for safety = RTH
     
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  10. RémyHeli

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    Craft might also experience wrong altitude readings therefore buffer definitively recommended.

    Also bear in mind that higher RTH means more battery consumption to reach altitude before returning to home point. If battery low, better returning home asap than wasting energy to reach over estimated altitude.
    Especially true if no more aircraft control so unable to stop ascending phase.

    Definitively good practice to review RTH altitude setting before flight.




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    #10 RémyHeli, Sep 14, 2016
    Last edited: Sep 14, 2016
  11. ussvertigo

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    If flying litchi mission, will not be able to change altitude unless mission is canceled/paused.


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  12. With The Birds

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    In addition to above commentary, a healthy RTH height usually means, in my experience anyway, signal it reestablished during the initial climb phase allowing me to cancel out and continue flying.
     
    TnG likes this.