RTH question/best practice

[WayneL41777]

I purchased my MP about four days ago, been reading as much as possible on here, videos, and the manual. I've flown it three times so far, only in beginner mode. I've not used RTH yet, was wanting to make sure I understand how it works first. I live in a hilly and forested area. The yard around my house is cleared, but I live on the top of hill, and lots of trees starting around 1000' out or so. So, I always make sure I have 9 or more satellites and good gps lock before I take off, and let it take a picture of the landing spot, but I've thus far not even tried RTH. I have a mountainside on one side of my yard that climbs up about 1000' gradually, and on the other side I have a drop off into a valley.

My questions: Will it do obstacle avoidance in RTH and hopefully miss trees? Say I set the RTH elevation to 150' and take off and fly it up the mountainside (let's say up to around 1500' relative to the take off point) then lower it on the other side where I know there's an open field and fly around at around 25' (relative to the field, which is probably 1000' above the take off point) for a while, which is below the elevation of some of the trees in the area. Then I press RTH, what happens? Yes, I know you should try to always have visibility to the drone, but if you saw where I live, you might understand. My nearest neighbor is miles down an upaved road. I might hit a deer or tree, but very little else to hit other than my own property.

 

[msinger]

Will it do obstacle avoidance in RTH and hopefully miss trees?

If obstacle avoidance is enabled, it'll attempt to detect and fly above the trees. The obstacle avoidance is not foolproof though, so it would be best to set the proper RTH Altitude prior to taking off each time.

 

[WayneL41777]

If obstacle avoidance is enabled, it'll attempt to detect and fly above the trees. The obstacle avoidance is not foolproof though, so it would be best to set the proper RTH Altitude prior to taking off each time.

So, it's best to set RTH altitude to exceed the highest obstacle you may be flying around, so it will always go to that altitude before returning (unless you really trust OA)?

 

[msinger]

So, it's best to set RTH altitude to exceed the highest obstacle you may be flying around

Yes. Make sure you add a buffer of 50 feet or so too since the current altitude displayed in DJI GO is just an estimate.

Check out this thread for more details on estimating the RTH altitude.

 

[Gary cato]

and remember if you are dropping behind that mountain, hill etc that the chances are you will suffer signal loss and RTH will be auto intiated when you do. i would not rely on OA as it can be confused by a lot of stuff, Best thing is make sure your RTH is above anything you might find on your path home and that the Mavic will fly a direct route back to you and not the route you took to get there.

So your flight path home may be nowhere near your flight path out

 

[mkp2020]

Also reminder that the Mavic will not detect obstacles above or to the side, so during RTH if it tries to avoid a tree by moving upward there is no guarantee there won't be an overhanging branch above resulting in a crash.

 

[Toruk Makto]

I set RTH at 120m (max leagal). I also set the battery smart RTH on.

This way I always have a clear rout back and Im warned at earliest point about battery life verses getting MP back safely.

You can always cancel RTH if the MP is nearby and you dont have to go to 120m to clear obsticals, as you will always have enough battery by returning at lower hieght.

 

[FoxhallGH]

A caution about setting RTH height though ... If it's a windy day, you can guarantee that the wind speed at 100ft AGL and above is much higher than where you lifted off from. If you fly down-wind, you can get the situation where pressing the RTH will put your drone at an altitude and speed where it won't be able to push back to you against the head-wind. If that's the case, you'll need to actually drop down to hedge-height and manually fly back to the launch point.

 

[Liv3rman]

A caution about setting RTH height though ... If it's a windy day, you can guarantee that the wind speed at 100ft AGL and above is much higher than where you lifted off from. If you fly down-wind, you can get the situation where pressing the RTH will put your drone at an altitude and speed where it won't be able to push back to you against the head-wind. If that's the case, you'll need to actually drop down to hedge-height and manually fly back to the launch point.

Beware of this scenario, I’ve had it happen to me. MP was 800m away, I hit RTH and it actually started drifting further away as the win was so strong at altitude. With only 20% battery left and in a mad panic I managed to lower it and bring it home manually and landed with 3% battery left!! Lesson learned about checking wind conditions at altitude before flying.