RTH altitude above max - nearly lost my quad.

[Zbip57]

outside the zone the drone's ceiling is still 65m, the reduced ceiling only comes into play inside or below the zone.

Yup, the Mini knows only that it has hit a wall. Outside it's still okay at its current height, just can't go any further in that direction.

But the Mavic 3 somehow knows not only that it's hit the same wall, but that it merely needs to automatically descend to be allowed to pass underneath the wall.

You'd think if it's possible for one model, why not all?

 

[Cymru]

Theres no bug to report here, but there is a valuable lesson to learn on the criticality of setting a good RTH height for each flight. Too low, and the drone might hit something. Too high and it could get blown away or get snagged on height restriction zones. I often fly at the edge of a 60m zone, so your experience here has been useful learning for me. Good you got your drone back just in time!

No bug but there is an argument here for a popup in the software explaining exactly why RTH has stopped and maybe a "descend to" advisory.
As can be seen here its confusing for people at the time and you don't have long to trouble shoot.

But yes, RTH should really always be set as low as possible whilst ensuring it'll clear any objects in the path. Mainly due to wind issues the higher it goes.

 

[Yorkshire_Pud]

The bug, as far as I am concerned, is that whilst the drone was under the restriction zone the log reports the RTH height to be higher the maximum permissible height ( Max height ) reported in the log.
Experimentation in actual flights shows that it is not possible to set the RTH height higher than the Max height and that reducing the Max height to below the existing RTH height will reduce the RTH height.
In fact, I suspect that the latter is how both RTH height and Max height ended up at 65m. With the sliders of the fly app I think the chances of manually being able to set the two to exactly the same value are slim at best.
Just to be clear, I understand what happened in this flight but I still think the above is a bug.
Also just to be clear, since the restriction zone temporarily reduced the 'Max height' I suppose that any 'correction of the bug' could be such that it brings about only a temporary reduction in the RTH height shown in the log.
I understand that that such a temporary reduction of RTH height would have still left the drone of this flight stuck at the wall since the original RTH height would have been restored once the drone was in unrestricted airspace.

 

[Cymru]

Maybe a better algorithm here would be RTH to follow *exactly* the route it came in to get back out - both altitude and position.

 

[Yorkshire_Pud]

That wouldn't be a bad idea and Failsafe RTH may do that, to a limited extent, in some drones ....... but it could be a power consuming, meandering route. Swings and roundabouts to every solution lol.

 

[Cymru]

Slow and would need to start much sooner but it would get back if there's an altitude zone or NFZ in the way.
Would need to be a user selectable option but in cases like the above i can see it being useful.

 

[RogerDH]

Slow and would need to start much sooner but it would get back if there's an altitude zone or NFZ in the way.
Would need to be a user selectable option but in cases like the above i can see it being useful.

I've always thought that the first action on signal loss should be to backtrack a bit to see if the connection was restored before resorting to RTH.

 

[FlySkyJumper]

to RTH

 

[FlySkyJumper]

I believe this is a major bug. But maybe I did something wrong.

I flew in an area with a restriction of 60m altitude. Did a hyperlapse. Quad was about 300m away. Was shooting a pier - so quad over the sea.

With 4 shots of a 250 shot video to go, I got a battery low warning and offer to RTH. I canceled to allow completion. I’d fly back in the next 10 seconds and there was enough battery for that easily.

It then quickly showed a forced RTH message. Battery seemed to stop quickly as it completed. Guessing processor usage when it renders the video onboard? So I let it auto RTH

It rose to 65m, turned towards me and - nothing. Just sat there warning me of the battery. I took over. Cancelled automatic RTH and stick forward to get home. I was over the sea.

Quad didn’t move. No matter which direction I went in. Then I got critical battery warning. But quad would not move. Hovering over sea. Maybe 100m from shore.

I noticed the altitude was red. It said 65. I realised I can descend. So went down to 60m and altitude went white again. Then I could move. Loads of beeping and warnings. Quad started descending by it’s self but I could fly toward. Maybe I cancelled the forced landing. Not sure. I was in panic mode. Made it to beach and landed on sand. Safe.

The issue is: why did it rise to above the maximum set altitude (set by the quad when it started up and warned that I was in a restricted zone)?? Because when it went into that area (above the max altitude set, and into a restricted area) - it would not RTH, and when I took over, it would not move. Except down. Which I realise later. Surely the RTH should be the set RTH value, or the max altitude for the area - which ever is lower. A useless RTH of 65 in a 60 is dangerous and neatly cost me my drone.

I opened settings after calming down and the RTH value was indeed 65 and the max altitude had been auto set to 60 based on my location.

Very scary when you quad is about to die - 100m out to sea over the waves! I’d hope DJI can update the logic on RTH altitude and max altitude. Seems very unsafe.

This is all outlined in the manual bro. Just read it...It'll explain how things work.

 

[Yorkshire_Pud]

This is all outlined in the manual bro. Just read it...It'll explain how things work.

Did you read the thread? There's quite a bit in here that isn't in the manual.

 

[FlySkyJumper]

Yes, I did...If you go to DJI's website to find your Drone, they are always updating information. That's where I go to confirm the information on this thread. (The source) Don't get me wrong, there's a wealth of information in these forums of course! However, as mentioned above by another user they explain to you what page you can find your answer in a very short form.

Always verify the answers you get. Just advise, take it or leave it.

 

[tiparoch]

Very interesting issue. I have had some serious trouble with RTH (set too low actually) and a bird being trapped. And I have also flown around alt. restricted areas NFZ. But not both at the same. What I have learned though is compass is real important. I started with a P-2 where you looked at LEDs to see if you had good GPS, so I STILL keep an eye on my compass condition and now I also keep a very very close eye on RTH alt.. Everytime. I think that is the lesson here, if you are anywhere near a restricted area with an alt. limit, set your bird accordingly. Anticipate a possible wall or hill, virtual or otherwise. As Two-Sticks said, the bird got stuck in a shelf. and asZbip said, not a glitch or a bug. Things around NFZ can get tricky. Best not to assume the bird and an app. will do everything. Very glad you got your bird back safely.

 

[Yorkshire_Pud]

Very interesting issue. I have had some serious trouble with RTH (set too low actually) and a bird being trapped. And I have also flown around alt. restricted areas NFZ. But not both at the same. What I have learned though is compass is real important. I started with a P-2 where you looked at LEDs to see if you had good GPS, so I STILL keep an eye on my compass condition and now I also keep a very very close eye on RTH alt.. Everytime. I think that is the lesson here, if you are anywhere near a restricted area with an alt. limit, set your bird accordingly. Anticipate a possible wall or hill, virtual or otherwise. As Two-Sticks said, the bird got stuck in a shelf. and asZbip said, not a glitch or a bug. Things around NFZ can get tricky. Best not to assume the bird and an app. will do everything. Very glad you got your bird back safely.

I think the RTH height and max height should be reset as appropriate for each new location.
The danger with the fly app is that it is FAR TOO EASY to accidentally change one, primarily the RTH height, whilst deliberately changing the other. So there is a need, with fingers like mine, to check both after you have changed one.

 

[CrowsFeet]

Yeah. It should be simple. RTH cannot be higher than any max restricted height between the controller and the drone. And that should be auto ah does. Same as the max Alt is auto handled. Maybe with an infonation pop up.

 

[Suren]

I flew the Mini 3 Pro today and was outside a Geo Zone higher than 60 meters, the height restriction is 60 meters for this area and the drone stopped outside the zone and did not lower its height like the Mavic 3 does and continue the RTH. Hopefully Dji pushes an update that makes the mini 3 behave like the Mavic 3 during RTH

 

[Droning on and on...]

I flew the Mini 3 Pro today and was outside a Geo Zone higher than 60 meters, the height restriction is 60 meters for this area and the drone stopped outside the zone and did not lower its height like the Mavic 3 does and continue the RTH. Hopefully Dji pushes an update that makes the mini 3 behave like the Mavic 3 during RTH

I didn't know the M3 did that... that's awesome!

IMO something like that shouldn't be a premium feature, just a feature of RTH on all DJI drones.