Return to home from a mountain

[Theoriginalgregtoo]

Hey All,

I have what I hope is a simple question. I'm flying a Mavic 3, and the drones altitude is determined from the point of launch.

My question is if I begin my flight from the base of a mountain, where the drone will register 0 feet AGL, and then fly it 5,000 feet up the mountain, from the drones perspective it is now at 5,000 feet, even if it's really only a few feet off the ground. If at this point return to home is activated (either manually or in response to a signal loss) how will the drone respond to this scenario? My hope is that it will fly back down the mountain safely in an efficient line from peak to base (similar to how it went up the mountain), but my fear is it will think it's at 5,000 feet and instead attempt to descend directly into the ground.

I know there are two options for return to home, option #1 being an optimal path and option #2 being a preset altitude. I'm guessing in this scenario I'd want the optimal path, but I'm afraid to try it without first checking with the community. I'd also like to avoid setting some ridiculously high preset altitude for obvious reasons of safety, because if the drone were to move away from the mountain still at 5,000 feet, this could pose an issue for any number of reasons.

Greatly appreciate any experience anyone can share.

 

[MAvic_South_Oz]

You should be able to set your drones max alt to 500m (1640'), to allow flight up a mountain side for example.
If landing and taking off again to gain another 1640', it will reset to 0' and new home point, but that comes with dangers too.
Looking at your dilemma, say you flew up to the 1640', and did a RTH or it went into failsafe RTH, your drone should descend safely to the home point, as per page 16 of the manual . . .

https://dl.djicdn.com/downloads/DJI_Mavic_3/DJI_Mavic_3_User_Manual_v2.0_EN.pdf

Obstacle avoidance is depended on in case there were possible peaks or other such on a more direct route.
Of course you can be watching this on the screen and take over anytime (if) you became concerned.

You would really need to use optimal RTH setting in that scenario.
If you used a pre set RTH alt, then being above that it would stay at the current height to RTH, which as you know would put you into shaky ground, ummm airspace, manned aircraft, higher wind, etc . . . also battery use would likely be much higher due to the more indirect route, flat line of travel, then a big descent, possibly in higher wind, head wind or otherwise.

 

[mavic3usa]

There aren't too many drones that will not work this way at a minimum: When RTH is triggered, the drone will ascend to the prescribed altitude (unless it is too close to the home point). Under no circumstances does the drone descend which means the RTH altitude preset means use this altitude or higher. More advanced drones with smarts and sensors may be able to appropriately descend or follow the clear path they previously took but for the most part, staying high is the rule.

Don't forget if you lose your connection and the drone starts to return home, it is likely you can regain the connection shortly and eventually re-take control over your drone and steer it to the appropriate altitude.

 

[Theoriginalgregtoo]

You should be able to set your drones max alt to 500m (1640'), to allow flight up a mountain side for example.
If landing and taking off again to gain another 1640', it will reset to 0' and new home point, but that comes with dangers too.
Looking at your dilemma, say you flew up to the 1640', and did a RTH or it went into failsafe RTH, your drone should descend safely to the home point, as per page 16 of the manual . . .

https://dl.djicdn.com/downloads/DJI_Mavic_3/DJI_Mavic_3_User_Manual_v2.0_EN.pdf

Obstacle avoidance is depended on in case there were possible peaks or other such on a more direct route.
Of course you can be watching this on the screen and take over anytime (if) you became concerned.

You would really need to use optimal RTH setting in that scenario.
If you used a pre set RTH alt, then being above that it would stay at the current height to RTH, which as you know would put you into shaky ground, ummm airspace, manned aircraft, higher wind, etc . . . also battery use would likely be much higher due to the more indirect route, flat line of travel, then a big descent, possibly in higher wind, head wind or otherwise.

Excellent answer and super helpful. I suspected that might be how it works with the obstacle avoidance kicking in and the drone basically hugging the ground as it moved down the mountain. I think the biggest concern in this case would be trees without leaves as those branches aren't always detected.

Thanks again, really appreciate your input.

 

[Theoriginalgregtoo]

There aren't too many drones that will not work this way at a minimum: When RTH is triggered, the drone will ascend to the prescribed altitude (unless it is too close to the home point). Under no circumstances does the drone descend which means the RTH altitude preset means use this altitude or higher. More advanced drones with smarts and sensors may be able to appropriately descend or follow the clear path they previously took but for the most part, staying high is the rule.

Don't forget if you lose your connection and the drone starts to return home, it is likely you can regain the connection shortly and eventually re-take control over your drone and steer it to the appropriate altitude.

Really helpful info regarding the RTH altitude being "this altitude or higher". Thank you for your contribution.

 

[Crashdummytest]

Hey All,

I have what I hope is a simple question. I'm flying a Mavic 3, and the drones altitude is determined from the point of launch.

My question is if I begin my flight from the base of a mountain, where the drone will register 0 feet AGL, and then fly it 5,000 feet up the mountain, from the drones perspective it is now at 5,000 feet, even if it's really only a few feet off the ground. If at this point return to home is activated (either manually or in response to a signal loss) how will the drone respond to this scenario? My hope is that it will fly back down the mountain safely in an efficient line from peak to base (similar to how it went up the mountain), but my fear is it will think it's at 5,000 feet and instead attempt to descend directly into the ground.

I know there are two options for return to home, option #1 being an optimal path and option #2 being a preset altitude. I'm guessing in this scenario I'd want the optimal path, but I'm afraid to try it without first checking with the community. I'd also like to avoid setting some ridiculously high preset altitude for obvious reasons of safety, because if the drone were to move away from the mountain still at 5,000 feet, this could pose an issue for any number of reasons.

Greatly appreciate any experience anyone can share.

I do mountain flights all the time. You will not get above max AGL from the base of a mountain. I always go as high up on the mountain as possible before take-off. I live in Norway and have the 1500 feet hard-limit in my mavic3. I have heard that 3000 feet as limit is possible with new firmware, but seemingly not in Norway. So your question is incorrect in my country/scenario due to the max AGL limit. Your mountain would need to be less than 1500 feet in height, and will pose no problem for your automated return flight.

 

[Telthecelt]

I think I mentiioned this elsewhere here but no harm in chipping in I guess? Flying in a few places in the Austrian tyrol this year I launched my Mini 3 Pro at somewhere around 6000ft. Th drone clearly knew my height above ground level (I think!) and frightened me twice by giving me a RC screen warning that I may be breaching local height restrictions (and on one occasion displaying my registration details!). On one of those occasions the max height allowed was only 30m and on the other 80m. I reset my max height but think I actually forgot the RTH height (presumably that would be overridden by the max height anyway. I assume...However, RTH operated perfectly fine for hand landing.

 

[GRH]

I enjoyed your comments and questions so much I decided to make a RTH example video from footage from last week.
Mavic 3 Pro
RTH height set at 180 feet
The drone was on cruise control the whole time until RTH took over, speed about 8-10 mph.
The launch point was at approx. 8160 feet.
The top of the hill about 8800 feet.
Difference in height: 640 feet.
The video is not from the drone itself but from a cached low rez copy that is stored on the RC Pro controller. It is what you would see if watching the screen on the controller.
Mavic 3 Pro RTH Example