RTH at night

[msinger]

Still a bit confusing, as they do not clearly explain which altitude limit they are referring to. However, it would appear to be the separate maximum altitude setting (that @Bad Santa is referring to as the ceiling height) rather than the RTH altitude setting.

They're referring to the max altitude setting, which is supposed to limit how high the aircraft can fly. The RTH altitude only comes into play when RTH is triggered, making sure the aircraft climbs to the correct height before heading back.

That's how these altitude settings have worked on all DJI drones for quite some time.

 

[DarR-T]

They're referring to the max altitude setting, which is supposed to limit how high the aircraft can fly. The RTH altitude only comes into play when RTH is triggered, making sure the aircraft climbs to the correct height before heading back.

That's how these altitude settings have worked on all DJI drones for quite some time.

As I've experienced and described in my previous posts, you can't rely on the RTH maximum altitude at night. Paying attention to your altitude, disabling the obstacle avoidance and setting a hard ceiling are your first line of defense.

 

[msinger]

As I've experienced and described in my previous posts, you can't rely on the RTH maximum altitude at night. Paying attention to your altitude, disabling the obstacle avoidance and setting a hard ceiling are your first line of defense.

There is no "max RTH altitude" setting.

As I mentioned above, the RTH Altitude simply ensures the aircraft climbs to the correct height before returning home. This feature works the same during the day or night since it doesn't depend on visual sensors to reach that set altitude.

 

[msinger]

You misread or misinterpreted.
I'm referring to the maximum RTH altitude which I set.
Moreover, the RTH altitude does not work at night unless you disable the obstacle avoidance as DJI suggested.

I think you might be misunderstanding what the RTH Altitude setting does. It sounds like you're thinking it prevents the drone from flying higher than the RTH Altitude once it starts returning home, but that's not the case, as mentioned above.

The RTH Altitude setting works properly at night, even when obstacle avoidance is enabled.

From what you described in your first post, the issue you experienced was related to the drone not following the Max Altitude setting, which is a known issue that can happen with models even older than the Air 3S. And as DJI mentioned, the only known workaround is to disable obstacle avoidance.

 

[Droning on and on...]

All this worry about RTH altitude control malfunction is easily avoided by just flying the drone yourself. Better to be the PIC than a spectator.

If you lose position awareness for the drone, it's dirt simple to follow the rubber band line on the controller map back to the home point.

This got me thinking about developing/honing instrument flying skills (what limited instrumentation we have, although it's sufficient). Go to a rural locale where there is very little risk of aircraft, people, etc., no lights so the view will be black through the camera, then fly around using the attitude/radar indicator. Go there first in daylight to fly around and determine minimum heights, etc.

Lots of risk, so I wouldn't do it with my Air 3, but maybe my Mini 3P, which is pretty much part of the drone legacy now, not anything I ever fly and wouldn't be beside myself if I lost it or got damaged.

 

[msinger]

In my experience the RTH maximum altitude setting was violated at night. This was confirmed by DJI as the drone's sensor see only black at night and interprets this as an obstacle thus it climbs attempting to avoid it. I'll just let others test the RTH max altitude in pitch black conditions with and without obstacle avoidance and take if from there.

But we're back to the point that an RTH maximum altitude setting doesn't exist.

The issue you're describing is related to the Max Altitude setting. The drone shouldn't go higher than that set limit once it climbs to the RTH Altitude and starts flying back to the home point. However, there is an edge case where the drone may detect an obstacle while returning, stop, and then climb higher than the set Max Altitude value.

Also, the drone doesn't rely on its visual sensors to reach the RTH Altitude. So whether the visual sensors are on or off doesn't affect how that feature works.

If you go back and look at that flight log, the flight probably looks like this:

 

[mavic3usa]

In my experience the RTH maximum altitude setting was violated at night. This was confirmed by DJI as the drone's sensor see only black at night and interprets this as an obstacle thus it climbs attempting to avoid it. I'll just let others test the RTH max altitude in pitch black conditions with and without obstacle avoidance and take if from there.

Honestly, if you would just use the correct terminology I think it would help everyone understand what you are describing but more so it would help everyone to know if you understand everything the same way we do. Words matter and details matter and there is no such thing as "RTH maximum altitude" or "maximum RTH altitude" or any form there of.

"RTH maximum altitude" means something slightly different than "RT altitude" and while the difference is subtle, the distinction is important in the situation which we are debating. If you don't mind just using the correct term "RT altitude" I think it might help with the overall understanding of what's going on here....for everyone.

When the drone's RTH feature is triggered, the user is able to dial in a suggested RTH altitude and depending on the circumstances, the drone may or may not execute that request exactly. It depends on a number of factors but in no way shape or form can a limit or cap be set by the user to prevent the drone from exceeding a certain altitude during the RTH process. Ideally there are other settings in the drone which can impact the maximum altitude a drone is allowed to fly (under any circumstances) but I guess we need further testing to see if that is entirely true or not. There may be bugs and there may be errors when features and functions don't work as expected or as programmed and we're just trying to sort it out. I'm willing to do some testing but lately it feels like we're in Jamaica here with all the rain.

I don't want my drone to malfunction and disconnect and fly-away and end up above the clouds for a passing manned aircraft to claim they "saw a drone flying at 15,000 feet, the operator must be crazy" so I am curious to what extent the settings and/or the built-in limitations are respected.

 

[MS Coast]

In my experience the RTH maximum altitude setting was violated at night.

The RTH altitude in the DJI Fly app is not a maximum limit. It's a minimum altitude.

If the drone is above the RTH altitude setting when RTH is invoked, it continues toward home at that altitude. If the drone is below the RTH altitude setting, it climbs to that altitude.

There is no setting that allows the user to set a maximum value specifically for an RTH operation, only an overall maximum altitude setting.

 

[mavic3usa]

It's not even a true minimum when the drone is only a few feet away, it won't even rise to the RTH setting on the way home.

We just need to leave off the references to the minimum and maximum (as a modifier to the RTH altitude setting) when it comes to the RTH feature because there are too many factors involved, one of which you often mention which is OA during darkness.

 

[Ken Schmidt]

I was at about the RTH preset height. I think Good Santa's idea is right on. Next time I'll turn obstacle avoidance off until I'm close to landing.

Good Luck my friend! Was that Lihue or Burns Field?

 

[GadgetGuy]

Honestly, I don't know how I can be more clearer than this:
The only thing I can possibly clear up is that the RTH altitude is a minimum not a guarantee of a maximum. Consequently, the aircraft will not RTH at the preset altitude (50m in this case). It could and will be higher in pitch black conditions up to the maximum altitude set (500m).
View attachment 186166

Your screenshot finally answers the question I have repeatedly been asking you.
You have CHANGED the default 400 foot Max Altitude under Flight Protection to 500m, and had to acknowledge that doing so could potentially violated FAA regulations.

So far, we haven't seen any evidence that the Max Altitude setting is being exceeded by RTH, even in your case, now that we know you set it to 500m.

 

[BossBob]

Honestly, I don't know how I can be more clearer than this:
The only thing I can possibly clear up is that the RTH altitude is a minimum not a guarantee of a maximum. Consequently, the aircraft will not RTH at the preset altitude (50m in this case). It could and will be higher in pitch black conditions up to the maximum altitude set (500m).
View attachment 186166

Unless you’ve got some kind of waiver that Flight Protection Max Altitude should be set at 120m or 400ft! That’s why the RTH height was going up and up. As for Max Distance set at No Limit, you really don’t want to keep your drone.

 

[GadgetGuy]

Unless you’ve got some kind of waiver that Flight Protection Max Altitude should be set at 120m or 400ft! That’s why the RTH height was going up and up. As for Max Distance set at No Limit, you really don’t want to keep your drone.

When he is mountain climbing to a 500m peak from the base, the 500m Max Altitude makes sense. Otherwise, the default setting of 120m should be left alone or even reduced, if in an Altitude Zone near an airport.

 

[DarR-T]

So far, we haven't seen any evidence that the Max Altitude setting is being exceeded by RTH, even in your case, now that we know you set it to 500m.

That is true, the Max Altitude setting was not violated. Heavers forbid!
Note to self, double check your settings during your pre-flight checklist.

Ok gentlemen, let's wrap this up.
I've made some mistakes but learned from it and hopefully others here will benefit.
As I've mentioned in post #42, my first line of defense for a night flight include:
* Setting a hard altitude ceiling according to what's required for your surrounding terrain while still maintaining within legal AGL limits,
* Disabling your obstacle avoidance should you want the RTH to return according to the outgoing flight path and
* Last but not least, adjust your settings accordingly, pay attention to your altitude and other potential hazards.

 

[mavic3usa]

That is true, the Max Altitude setting was not violated. Heavers forbid!
Note to self, double check your settings during your pre-flight checklist.

Ok gentlemen, let's wrap this up.
I've made some mistakes but learned from it and hopefully others here will benefit.
As I've mentioned in post #42, my first line of defense for a night flight include:
* Setting a hard altitude ceiling according to what's required for your surrounding terrain while still maintaining within legal AGL limits,
* Disabling your obstacle avoidance should you want the RTH to return according to the outgoing flight path and
* Last but not least, adjust your settings accordingly, pay attention to your altitude and other potential hazards.

Cool, also you might want to think about flying in controlled airspace at night without authorization.