After deliberately running out of battery, in order to try out the emergency RTH, I see that if the aircraft is below the set RTH altitude, it will lift to that altitude and then fly home. In the DJI Fly app (Android), the lowest RTH altitude that can be selected is 20 m. This is not an issue when the aircraft is high up, far away and there may be obstacles on the way home. But -- when flying at very low altitude, for instance below trees or indoors, running out of battery and auto-engaging RTH will make the MA2 commit suicide, as it will try to lift to 20 m and will hit the trees/ceiling from below.

So please, DJI, remove the low RTH altitude limit in next app update!

Is this something that you have tested? I had the understanding that OA would still be in affect so in the case of a tree, it would try to avoid said tree. If not then yes, this would need to be addressed.

I have only tried it in an open field, with no obstacles above it. Fortunately.
As far as I know, the MA2 has obstacle avoidance only to front, back and downward - not up, nor sideways.

You do still have manual control of this, I mean I don’t think these drones are equipped with enough AI to tell if a tree is above them or they might meet a train flying home at low altitude. Some responsibility must be given to the pilot. It’s not armchair flying. And every scenario is covered in your manual.

I didn't try to maneuver it during the emergency RTH. Even though I knew the battery was low, I was surprised when I lost control and it suddenly climbed up to those 20 meters pretty fast. There might not be enough time to abort the climb if the drone is below trees, bridges, ceilings etc.

Simple solution.  Don't let the battery get that low!  You are the pilot - take at least some responsibility for your flight.  At the very least, if you know your battery is getting low, don't go into a situation where the known low battery RTH operation would cause a problem.  Personally I have intentionally let the battery get low enough that my Mini auto-landed - once to see what it would do.  However, I did that when it was less than 5 feet from where it took off and an altitude of less than 5 feet.  In other words, it was right in front of me...

I agree that we as pilots need to take responsibility for our flights. We are pilots first when in the air and creators second. If I'm keeping an eye on my battery and my flight, then RTH shouldn't be of such a concern. You have to weigh out the risk vs reward in these situations.

If you are flying "low", under the canopy of trees, buildings, whatever, should have set the RTH to "Hover".
This was completely avoidable.....
Period....

Flycaster Posted at 9-14 08:38
If you are flying "low", under the canopy of trees, buildings, whatever, should have set the RTH to "Hover".
This was completely avoidable.....
Period....

You cannot set Rth to hover. You can set failsafe Rth , IE Loss of signal to land return or hover.

K6CCC Posted at 9-14 08:06
Simple solution.  Don't let the battery get that low!  You are the pilot - take at least some responsibility for your flight.  At the very least, if you know your battery is getting low, don't go into a situation where the known low battery RTH operation would cause a problem.  Personally I have intentionally let the battery get low enough that my Mini auto-landed - once to see what it would do.  However, I did that when it was less than 5 feet from where it took off and an altitude of less than 5 feet.  In other words, it was right in front of me...

yep, so true


and, what about if you are in full control (ready to cancel the RTH climb) and.....connection loss!

OMG, i see it climb and climb and  *&%#*!#%*%!#

So or put Hover in the advanced settings or simply, stop flying when batt level reach 30% in such area conditions.
cheers
JJB

I completely agree that it should be possible to set the altitude that the user wants, there is no minimum, on the other hand, I suppose that DJI will have its reasons to put a minimum of 20 meters, if someone can shed light on this, it will be I would appreciate it.
Another issue, for me very annoying, is that we can not put the minimum battery that we want the drone to warn us, as if it can be done in DJI GO with my dear Phantom. It should be configurable to how much you want to rush the batteries.On my last flight, flying below 19% battery without realizing it, the application does not warn or give you a simple message, I do not like to rush the batteries so much.

and, what about if you are in full control (ready to cancel the RTH climb) and.....connection loss!

OMG, i see it climb and climb and  *&%#*!#%*%!#

You may be aware that I pretty much was in a similar situation about 10 days ago.  In my case RTH was in progress due to loss of signal (WiFi interference in an area known for it - so it was expected), and when it got close, I could tell that it was going to descend into the edge of a tree.  In my case, the app became non-responsive on my phone so I could not cancel the RTH.  My MAJOR error was that I always used the RTH button on the screen rather than the physical button on the RC, so when the app locked up, I failed to think about using the button on the controller to abort the RTH.  My other error was taking off (and therefore setting the RTH) a little too close to the tree - under the assumption that I would normally abort the RTH when the Mini got close...

But I fully admit that it was my mistake - even though a contributing factor was the app locking up.  I wrote it up in this post:  https://forum.dji.com/forum.php?mod=viewthread&tid=224044

or put Hover in the advanced settings or simply, stop flying when batt level reach 30% in such area conditions.

All part of taking responsibility for your flight.  Similar concept to flying real airplanes.  I can assure you that if I am making a nighttime flight over mountains in instrument conditions, I am going to be planning a fuel stop with far more gas left in the tanks than if I was flying the pattern at my local airport on a bright sunny day!  Plan for your conditions - and adapt if they change.  OK, the stakes are higher in the real airplane (I die), but the concept is the same.

There is a ten-second countdown timer before low battery RTH initiates. Cancel it and it won't RTH. Also, if the drone is within 20m of your position it will fly back at the same altitude. Always best practice to monitor the drone and battery level during flight. Always aim to have the drone on the ground in front of you with 20% remaining and never fly indoors or under trees with a low battery warning. At least at 20m AGL the drone won't hit a child returning to you...  

K6CCC Posted at 9-14 10:00
and, what about if you are in full control (ready to cancel the RTH climb) and.....connection loss!

OMG, i see it climb and climb and  *&%#*!#%*%!#

nice story   ;-)

I learned myself to never use the soft buttons in the app, so RTH and CX button always on the RC!
Fuel/mission planning is essential in aviation, same for situational awareness., where to land if...

Many things counts for drone flying as well, it is not a child toy hobby.

cheers
JJB

hallmark007 Posted at 9-14 09:36
You cannot set Rth to hover. You can set failsafe Rth , IE Loss of signal to land return or hover.

I don't have a Mini, never played with the "Fly" app, but seems like DJI missed something important...
My apologies...

You might want to read this thread:   https://forum.dji.com/forum.php?mod=viewthread&tid=223423

JM.REYES Posted at 9-14 09:51
I completely agree that it should be possible to set the altitude that the user wants, there is no minimum, on the other hand, I suppose that DJI will have its reasons to put a minimum of 20 meters, if someone can shed light on this, it will be I would appreciate it.
Another issue, for me very annoying, is that we can not put the minimum battery that we want the drone to warn us, as if it can be done in DJI GO with my dear Phantom. It should be configurable to how much you want to rush the batteries.On my last flight, flying below 19% battery without realizing it, the application does not warn or give you a simple message, I do not like to rush the batteries so much.

I think safety is the reason as with most failsafe auto modes. If you lose signal and your Rth is set at 2m then people are now at risk you no longer have control. All people piloting should ALWAYS be aware of the tallest structures within their flight path , this is explained in the manual. So if you take off without changing the Rth height leaving at 20 m then it should be taken that there is nothing in your flight path above 20m. My thinking is people, trucks and cars should be protected at all times from a drone no longer under the control of the pilot.

hallmark007 Posted at 9-14 16:03
I think safety is the reason as with most failsafe auto modes. If you lose signal and your Rth is set at 2m then people are now at risk you no longer have control. All people piloting should ALWAYS be aware of the tallest structures within their flight path , this is explained in the manual. So if you take off without changing the Rth height leaving at 20 m then it should be taken that there is nothing in your flight path above 20m. My thinking is people, trucks and cars should be protected at all times from a drone no longer under the control of the pilot.

I don't know too many people who are 20 meters tall. How about a minimum of 5 meters? Or are we concerned about hitting some clown on stilts.

I guess we should not use the image on the DJI site of flying inside a concrete drain pipe as an example of how to use these.

I once flew under a tree when the drone (Mavic Pro) initiated a RTH, so it started to climb suddenly, hit the tree, propellers got destroyed and drone fell down to the ground.

Never a good idea to fly under stuff, particularly when battery is low.

Of course it's our own responsibility to fly safely, be aware of aircraft and battery status, surroundings etc, but we are humans. Humans make errors. Technology should help mitigate damage from human errors -- not cause more damage. It's not a big deal for DJI to remove the min 20 meters RTH altitude limit in their app, and I can't see why it would be a problem. This setting should be checked and set before each and every flight anyway.

As for not flying beneath obstacles when the battery is low, this is not an option. Much of my work with the MA2 is at low altitude, among and underneath obstacles.

fans273d858a Posted at 9-14 22:39
I once flew under a tree when the drone (Mavic Pro) initiated a RTH, so it started to climb suddenly, hit the tree, propellers got destroyed and drone fell down to the ground.

Never a good idea to fly under stuff, particularly when battery is low.

Deleted with after thought

GaryDoug Posted at 9-14 19:17
I don't know too many people who are 20 meters tall. How about a minimum of 5 meters? Or are we concerned about hitting some clown on stilts.

I guess we should not use the image on the DJI site of flying inside a concrete drain pipe as an example of how to use these.

Well go read my post again, I think driving a truck and to see a drone heading straight for you even 5 m it’s still going to cause a reaction.
And what do you think user would say if he loses signal and his drone Rth in failsafe at 5m altitude and smacks into someone’s house. I can tell you, he would say why is there no responsible Rth default.

Your 5m will not stop a drone going up and hitting a tree will it .
I’m amazed sometimes that some flying these drones expect a babysitter with them on all occasions. Many have flown in tricky locations and never crashed, this does not happen by luck alone.

Mooonlight Posted at 9-14 23:02
Of course it's our own responsibility to fly safely, be aware of aircraft and battery status, surroundings etc, but we are humans. Humans make errors. Technology should help mitigate damage from human errors -- not cause more damage. It's not a big deal for DJI to remove the min 20 meters RTH altitude limit in their app, and I can't see why it would be a problem. This setting should be checked and set before each and every flight anyway.

As for not flying beneath obstacles when the battery is low, this is not an option. Much of my work with the MA2 is at low altitude, among and underneath obstacles.

It’s strange you think you should do all the preflight checks, and once you start flying ignore all the actual flying challenges , believe me if I thought this was not a challenge I’d be doing something else and I expect so would most.
Lowering the default has the potential to cause just as much damage or a lot more damage than default of 20m.
I think it makes a lot more sense to be extra careful when flying under trees, you can also preform a preflight for this to mitigate and problems that might occur.

K6CCC Posted at 9-14 08:06
Simple solution.  Don't let the battery get that low!  You are the pilot - take at least some responsibility for your flight.  At the very least, if you know your battery is getting low, don't go into a situation where the known low battery RTH operation would cause a problem.  Personally I have intentionally let the battery get low enough that my Mini auto-landed - once to see what it would do.  However, I did that when it was less than 5 feet from where it took off and an altitude of less than 5 feet.  In other words, it was right in front of me...

if you know your battery is getting low, don't go into a situation where the known low battery RTH operation would cause a problem

I (am trying to) use this rule as well. BTW To be familiar with the machine is important. I tried low battery situation after 5km of flying, MA2 performed noncancelable auto-landing at 9% of battery, battery info after landing at the picture...

#I think indoors you should use STATIONARY FLIGHT in emergency or loss of signal ... or landing as the last option. regards Reply Here#

hallmark007 Posted at 9-15 00:58
Well go read my post again, I think driving a truck and to see a drone heading straight for you even 5 m it’s still going to cause a reaction.
And what do you think user would say if he loses signal and his drone Rth in failsafe at 5m altitude and smacks into someone’s house. I can tell you, he would say why is there no responsible Rth default.

"I’m amazed sometimes that some flying these drones expect a babysitter with them on all occasions. "

We do anything to keep you entertained Dave ;-)

Hi. I am sorry for the trouble this has caused. With regards to this concern. I will cascade this matter to our designated DJI support team for further evaluation. Again I am sorry for the trouble. Thank you.