RTH on hilly terrain and tall buildings

[frcaloy]

Just want to ask if the DJI Air2 or Air2S will climb over the preset RTH altitude or try to bypass multiple obstacles if it encounters obstacles higher than the preset altitude as in the case of high hills and tall buildings.

Thanks

 

[Meta4]

Just want to ask if the DJI Air2 or Air2S will climb over the preset RTH altitude or try to bypass multiple obstacles if it encounters obstacles higher than the preset altitude as in the case of high hills and tall buildings.

It will try, but it's always better to set an appropriate height to clear any obstacles on your RTH path rather than hoping obstacle avoidance will do what you want.

 

[Yorkshire_Pud]

I am not being awkward but you really should go and read the manuals for those two, their RTH behaviours are quite complicated and both feature one behaviour, "Power saving RTH", that could, as I understand it, leave the drone WELL above 400ft AGLwhen it gets over the homepoint.
Google the relevant drone and "manual " and you should find the manual download pages easily enough.
Then come back and ask about anything you even think you do not undertand, it's not an area where you want misundertandings.

 

[TTP]

I'm flying my M2P in a restricted area, max height 50m. The topography is up and down, put in new battery at the lowest point, flew a long left turn at max height 50m, over a low hill with trees, lost visibility of the drone, because of the treetops, should have seen it after a few seconds, but no.
What happened?
The top of the trees is about 55 m, my 50 m limit, takes my drone. Lesson learned.
PS.
Found the drone unharmed on the ground.
Never use OA.
DS.

 

[frcaloy]

Read the manual, specifically pages 13-14. Still not clear if the Air2 or Air2S will climb over the obstacle it is higher than 400' AGL or over the assigned RTH altitude. Not clear if it will bypass the width of an entire building.

 

[frcaloy]

I'm flying my M2P in a restricted area, max height 50m. The topography is up and down, put in new battery at the lowest point, flew a long left turn at max height 50m, over a low hill with trees, lost visibility of the drone, because of the treetops, should have seen it after a few seconds, but no.
What happened?
The top of the trees is about 55 m, my 50 m limit, takes my drone. Lesson learned.
PS.
Found the drone unharmed on the ground.
Never use OA.
DS.

Thanks for info. Altitude is our friend but there are obstacles higher than 400' AGL. Will avoid flying in those areas.

 

[Volatus Drones]

When we train our customers we tend to tell them to set the RTH as high as reasonably makes sense. The highest obstacles in the area look about 50 ft. high? Set RTH 150 ft. Also, we tell them, when applicable, to bring the aircraft back themselves and not too fully rely on RTH or AI of the drone. We've seen too many crashes that could have been avoided if the pilot stayed in command instead of relying on the autonomy of the drone.

 

[Yorkshire_Pud]

The following is speculation. The RTH height is not a hard limit that you do NOT wish the drone to break, it is more a 'floor', intended to ensure the drone clears obstacles by a safe margin. Whereas the maximum height ceiling that you set, and or the 500m ceiling that DJI sets, are ceilings that the drone should not go above.

Indeed you may be flying higher than the RTH height and, in general, if RTH height was meant to be a "do not exceed" ceiling then the drone would descend to comply, in general no DJI drone does descend th RTH height.

As such I suspect the drones would climb past the RTH height if needs be but I doubt obstacle avoidance could force the drone to break the maximum height you set.

In fact I have seen a M2P or M2Z do something like this. It turns out one of its 'fancy' setting had been switched on that meant it should do an RTH at VERY LOW level, maybe 2m or something like that. It started the movement towards the home point at such a height but there was an building in the way, the drone stopped horizontal movement and climbed until it had a clear path to the home point, probably around 12m, and restarted the forward height.

 

[Droning on and on...]

I'm flying my M2P in a restricted area, max height 50m. The topography is up and down, put in new battery at the lowest point, flew a long left turn at max height 50m, over a low hill with trees, lost visibility of the drone, because of the treetops, should have seen it after a few seconds, but no.
What happened?
The top of the trees is about 55 m, my 50 m limit, takes my drone. Lesson learned.
PS.
Found the drone unharmed on the ground.
Never use OA.
DS.

If I understand correctly, you set the operating ceiling to 50m. The aircraft treats that as a hard limit and will not exceed it, regardless of OA needs.

In my opinion the height and range limits should always be set to maximum (500m and unlimited) for exactly the case you encountered. Where there is a flight ceiling, that should be managed by the pilot. You are arguably creating a safety risk by limiting your freedom of movement, an emergency may require you to break these limits to avoid injury or property damage to a third party.

maintaining an altitude ceiling while flying is so easy with these drones I almost want to say that someone who can't shouldn't be in the air in the first place.

 

[Yorkshire_Pud]

In my opinion the height and range limits should always be set to maximum (500m and unlimited) for exactly the case you encountered.

On the other hand, in my opinion the height limt should never be set above 400ft unless you are flying up hills etc. because it is a safety risk. Especially with the God awful setting sliders in the FLY app.
I once, accidentally, set an FLY app RTH height well in excess of 400 ft on one flight, The setting was ony acceptable to the FLY App because I had the Max height ceiling raised to facilitate an uphill flight.

In a later portion of the same flight a disconnection occurred over ground that was somewhat below the home point. The result? A climb to an RTH height well above 400ft AGL.
If the max height setting had been under 400ft the app would not have accepted the erroneous RTH height. Similarily if, after the drone came away from the hill, I had reduced the Max height to under 400ft the RTH height would, I believe, have been reduced to be the same as the max height..
For the record, my normal flat land Max height is well below 400ft and I feel there is absolutely no safety risk in so doing.

 

[Droning on and on...]

On the other hand, in my opinion the height limt should never be set above 400ft unless you are flying up hills etc. because it is a safety risk.

How? Just don't fly over 400ft... it's right there in the display. Flying at 420ft is not meaningfully more dangerous than 400ft.

OTOH, having a hard ceiling is a very real safety concern if you need to exceed that height to avoid a collision (Raptor coming up to attack from below), and your drone won't follow your commands.

I'm more concerned with not being able to control my aircraft in a split-second emergency than breaking a rule that I can then argue was justified.

You judge this differently, which is good... different perspectives give others a more complete picture to make up their own minds.

In my opinion, relying on crippling drone functionality to enforce limits that need to be followed is both lazy, and potentially dangerous (i.e. the crash in the OP). Everyone controlling an aircraft in the air should always be aware of it's altitude, and in direct, conscious control of it.

It's trivially easy with altitude-holding modern drones.

 

[R.Cowan]

Just want to ask if the DJI Air2 or Air2S will climb over the preset RTH altitude or try to bypass multiple obstacles if it encounters obstacles higher than the preset altitude as in the case of high hills and tall buildings.

Thanks

Made the mistake once with my Air 2 getting too close and losing signal near a 1100 ft building. Didn't have the RTH set high enough and the building was too wide, so it just hovered until I moved and regained signal.

 

[frcaloy]

Made the mistake once with my Air 2 getting too close and losing signal near a 1100 ft building. Didn't have the RTH set high enough and the building was too wide, so it just hovered until I moved and regained signal.

Thanks for this input. Was the RTH set on 'bypass'?

 

[R.Cowan]

It was, but found myself about 20 ' away from the building. I was moving back to compose a shot and didn't realize I had gotten that close. RTH set at 850 ft. I was flying at about 200 ft. It rose to the RTH 850' but couldn't go over and building was too wide for it to go left or right. Careless on my part and lesson learned.

 

[frcaloy]

Thanks for the lesson. I'll be careful with tall buildings.

 

[TTP]

If I understand correctly, you set the operating ceiling to 50m. The aircraft treats that as a hard limit and will not exceed it, regardless of OA needs.

In my opinion the height and range limits should always be set to maximum (500m and unlimited) for exactly the case you encountered. Where there is a flight ceiling, that should be managed by the pilot. You are arguably creating a safety risk by limiting your freedom of movement, an emergency may require you to break these limits to avoid injury or property damage to a third party.

maintaining an altitude ceiling while flying is so easy with these drones I almost want to say that someone who can't shouldn't be in the air in the first place.

Have kommersial flight in to Stockholm Arland at ca 650m, I take no risk, 50m will be my max.