This easy to read guide is here
https://store.dji.com/guides/how-to-use-the-djis-return-to-home

which is quite confusing... Lots of rules which is hard to remember in the heat of the moment.

Again it’s worth noting that the Spark is a little bit different with how DJI’s Return to Home operates. When the Spark’s RTH is triggered, if the drone is between 3 meters to 20 meters from its home point then the drone will just land automatically with the RTH at Current Altitude option disabled (the default setting in DJI GO 4). If the option is enabled then the Spark will not ascend if already at height of 2.5m or more, but if below 2.5m then it will ascend to 2.5m during its RTH. Finally, if the Spark is more than 20m meters away then it’ll ascend to the set RTH height before heading back home.

One last thing you need to be aware of during the Spark’s RTH is that if it is farther than 100 meters away then the aircraft will return home at a speed of 10m/s and it can’t avoid obstacles. If RTH is used less than 100 meters away then Obstacle Avoidance will be enabled and the Spark will avoid obstacles if the lighting conditions are adequate.

Everyone should have set RTH higher than any obstacle in the area they are flying in, so no need for OA.

I agree it’s confusing. Too many arbitrary rules.
And I agree that OA is unneded, as it descendss vertically. OA would only make sense if it was low and out of sight.
If more than 100 meters away, it could hurry back, and let the 20-100 meter rule take over..

More than 100 meters away and if you have to emergency hit RTA then you may very well NEED OA....or if it's low on battery or looses signal. Seems like a mistake from DJI?

DJI has given the spark and it's users lots of capabilities.  Some of those capabilities may allow it to perform actions that do not conform to the regulations which apply, and that's ok.  Cars are the same way (the driver can do all kinds of things using the car's capabilities but result in a violation of law).  In the case of a spark, one COULD fly it to where obstacles exist between it and home point, and that implies that the pilot has flown out of line of site (in violation of US regulations).  I can envision a scenario, however, where OA could save the spark if things really get out of control...  if spark loses gps and if signal is lost between spark and rc (and that's a rare event but we've had reports of it) then OA could help to preserve the craft (and maybe keep people safe).

Hansolo Posted at 2017-9-27 09:25
More than 100 meters away and if you have to emergency hit RTA then you may very well NEED OA....or if it's low on battery or looses signal. Seems like a mistake from DJI?

If you set you RTH height before you fly as you should to a height above all obstacles, and it will also tell you in your manual that you must do this then you won’t have any problem.
It also tells you in your manual RTH should only be used in emergency situations.

If it’s returning because of low battery or emergency then it will first ascend to its RTH altitude set by you . You are fully aware of this before you fly. where do you think you will have the problem?

I agree that there are many different scenarios that go into how the Spark proceeds in an RTH situation.  My first suggestion is that you evaluate your RTH settings in the DJI Go 4 app as part of your pre-flight checklist to ensure that your settings are appropriate for the environment you will be flying in for this particular flight.  By doing this, you are mentally preparing for your flight, thinking about your situation, and thus if the unexpected happens, you will be much more prepared for it when it occurs.  

I created a video tutorial about the RTH settings and procedures and posted it in the forum here a while back.  

https://forum.dji.com/thread-113429-1-1.html

Kloo Gee has put together an amazing video describing the different RTH capabilities for the Spark with demonstrations ...

It’s missing demoing the OA abilty if RTH is initiated at 20-100 meter.

Great video! Thanks for the post

If... else...if... else... then

heliman Posted at 2017-9-27 10:52
It’s missing demoing the OA abilty if RTH is initiated at 20-100 meter.

Yes it is.."

however probably is one of the best way of it work

Sparky_17 Posted at 2017-9-27 10:01
Kloo Gee has put together an amazing video describing the different RTH capabilities for the Spark with demonstrations ...

Thanks for sharing. It is a good video about RTH.

Charles Adams Posted at 2017-9-27 09:38
DJI has given the spark and it's users lots of capabilities.  Some of those capabilities may allow it to perform actions that do not conform to the regulations which apply, and that's ok.  Cars are the same way (the driver can do all kinds of things using the car's capabilities but result in a violation of law).  In the case of a spark, one COULD fly it to where obstacles exist between it and home point, and that implies that the pilot has flown out of line of site (in violation of US regulations).  I can envision a scenario, however, where OA could save the spark if things really get out of control...  if spark loses gps and if signal is lost between spark and rc (and that's a rare event but we've had reports of it) then OA could help to preserve the craft (and maybe keep people safe).

Believe me when I tell you that losing signal between the spark and the RC is not as rare as you think.  Read my forum (Lost Signal).

fansf31b969e Posted at 2017-9-27 20:27
Believe me when I tell you that losing signal between the spark and the RC is not as rare as you think.  Read my forum (Lost Signal).

Oh I know and agree.  What I was referring to (but apparently not effectively) is the combination of gps loss AND RC signal loss is as a combined set of circumstances a rare event.

In my RC-Spark tests I've found 5.8Ghz to be unsatisfactory (which is a polite way of saying it SUCKS!), and my efforts (though few) to test 2.4Ghz has been much more promising.

I've never tried 5.8Ghz as I have no need to switch.  I've had zero issues with the current 2.4Ghz set up.

Can anyone confirm:
1) RTH at current altitude
2) Return-to-home altitude
are actually separate things. 1) controls how the spark behaves when it’s between 3-20meters. 2) controls how the spark behaves >20meters. Is that right?

RTH rules  are fundamentals every SPARK pilot must know to use the correct judgement and common sense during take off and landing. Else you will be creating a forum title "My SPARK fell "or "My SPARK lost "  :)

DJI Elektra Posted at 2017-9-27 20:04
Thanks for sharing. It is a good video about RTH.

Elektra,  the new DJI GO4 android version 4.2.6 does not show the green font message "Home point updated  " But while we check the flight logs, it is recording.

Sparky_17 Posted at 2017-9-27 10:01
Kloo Gee has put together an amazing video describing the different RTH capabilities for the Spark with demonstrations ... https://www.youtube.com/watch?v=ghRZNUbV0s4

nice video and explaination

fans427e5cb5 Posted at 2018-2-16 06:50
Can anyone confirm:
1) RTH at current altitude
2) Return-to-home altitude

if you select RTH at current altitude, when you enable RTH, the spark will fly back to home location at whatever altitude is is at.  I suppose this would be quicker

If you set the RTH altitude and the drone is basically NOT right next to you, it will fly up to the set altitude then return to home and descend straight down to the home point.  (this is obviously the safe option as you can set your altitude higher than the tallest obstacles in your area.   

This is the logic I see on it, but haven't tested it. I am not sure why DJI call it "RTH at current Altitude" when the more important part of this function is "land where it is if within 20m"

Lets try that again. Someone please correct me if I am wrong.

X =   Return-to-Home altitude entered manually
Distance	Height	RTH at current height = on	RTH at current height = off
0-3m	Any   height	Lands   where is	Lands   where is
3-20m	<2.5m	Rise to   2.5m, go to home point	Lands   where is
	2.5m or   above	Go to   home point at current height	Lands   where is
20-100m	Any   height	Height   to X, go to home point using OA	Height   to X, go to home point using OA
100m +	Any   height	Height   to X, go to home point fast, without OA	Height   to X, go to home point fast, without OA

Great RTH video, thanks for putting this together!

S.J Posted at 2018-2-16 07:08
Elektra,  the new DJI GO4 android version 4.2.6 does not show the green font message "Home point updated  " But while we check the flight logs, it is recording.

S.J, did it happen every time? Please tell me the model of your device. Thanks for your support.   

DJI Elektra Posted at 2018-2-28 00:00
S.J, did it happen every time? Please tell me the model of your device. Thanks for your support.

the model is DJI SPARK..is there any other model ?  It did happen everytime.   There is absolutely no indication of the green message or the voice  confirming that Home Point has been updated.

S.J Posted at 2018-2-28 03:44
the model is DJI SPARK..is there any other model ?  It did happen everytime.   There is absolutely no indication of the green message or the voice  confirming that Home Point has been updated.

Ummm, Electra asked for the model of your device....meaning your phone, not the Spark.

S.J Posted at 2018-2-28 03:44
the model is DJI SPARK..is there any other model ?  It did happen everytime.   There is absolutely no indication of the green message or the voice  confirming that Home Point has been updated.

I see. Please tell me the mobile you use. Sorry for the misunderstanding.

Outlier22 Posted at 2018-2-16 08:17
if you select RTH at current altitude, when you enable RTH, the spark will fly back to home location at whatever altitude is is at.  I suppose this would be quicker

If you set the RTH altitude and the drone is basically NOT right next to you, it will fly up to the set altitude then return to home and descend straight down to the home point.  (this is obviously the safe option as you can set your altitude higher than the tallest obstacles in your area.

Exactly, that’s my reasoning too. To me, there’s nothing confusing about RTH, since I don’t see why I would ever wanna use it if the AC is only 20 meters away, so I always just ignored that part.

To be on the safe side, set the RTH altitude really high (within the legal limits), that way you don’t have to worry about obstacles. I would never set RTH at current altitude, since you cannot know where your aircraft is going to be in case of a lost connection (which could trigger RTH).

DJI Elektra Posted at 2018-3-1 01:18
I see. Please tell me the mobile you use. Sorry for the misunderstanding.

Samsung Note 5.  In all the previous versions , the message and the voice message were indicated promptly.

So if you look at the chart provided...and I never thought of this before...I'm not really worried about RTH <3 meters as that's pretty close to me.  The 20-100 and >100 are the same.  It's the 3-20 that now bothers me.  I fly low over rocky, scrubby terrain a lot here in Arizona...also low over water on vacations.  So if I lose connection in these cases the drone immediately lands in the rocks/water if I don't have Return at Current Altitude selected.  Granted, you don't expect lost of signal that close in, but it's still a possibility.  And if I'm flying VLOS from 3-20 meters, there's probably no obstacle between me and the drone so OA is not important and RTH at current altitude is safe.  I've had this drone since last July and never had Return at Current Altitude selected.  I think I'm going to re-evaluate that decision.

RTH sounds problematic in high winds and over water.  RTH with OA on, sounds pretty slow.  Wind speed and the OA speed might be why some people, wanting another drone under warranty, claim it just hovered in place.

S.J Posted at 2018-3-1 08:21
Samsung Note 5.  In all the previous versions , the message and the voice message were indicated promptly.

Thanks for your update. I would forward this situation to our engineers for further check.

ZukySpark Posted at 2017-9-27 11:04
If... else...if... else... then

if... then... else...*

What will happen if I lose remote connection?  Unlike the other drones, I don’t see any options for what the drone will do.