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RTH or Auto Land? What happens when spark loses connection?
6086 36 2018-1-3
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ADDvanced
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I had a GPS/Yaw/IMU/compass Error mid flight, and the drone went into Atti mode.  When I last had information on it, it had 69% battery.

So two schools of thought:

1.  Drone just hovers/drifts away until battery is low, waiting to reconnect, in which case I will never find it again

2.  Drone, with IMU/Yaw/Compass/GPS errors is in atti mode, and realizes it won't be able to return home, and auto lands at a rate of 9.8 ft per second from last known coordinates


This is a fairly straightforward question and so far the answers have been mixed.  I'd like to know with more certainty as it affects if I am going to look for more drone again.  I have already spent 4 hours looking for it.
2018-1-3
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DJI Elektra
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Hi, sir. Please note that if the spark disconnect with RC over 3 seconds, it will trigger RTH when the drone have a good GPS signal. If spark has no GPS signal, it will hover. Please look at our user manual carefully, you can turn to page 13. If you have more doubt, please infom us.
2018-1-3
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S-e-ven
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Gone with the wind, methinks
2018-1-3
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DJT_MVSP
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When spark loses connection in ATTI mode, it will descent until it's close to the ground and hover there until:
1. There's GPS signal and starts to RTH

2. There is RC signal and pilot takes control

3. The battery is critically low and starts to land

So hopefully it doesn't land in water or hit an obstacle on its way down or when it RTH
2018-1-4
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JJBspark
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DJT_MVSP Posted at 2018-1-4 00:27
When spark loses connection in ATTI mode, it will descent until it's close to the ground and hover there until:
1. There's GPS signal and starts to RTH

Hiya, do you have the source where i can read this information ? Its not in the spark manual (or i need better specs, wich page?)

DJI; can you answer this question ?
2018-1-4
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DJT_MVSP
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I learnt that from my experience; That's how it behaved when it entered ATTI and lost connection. That day, I took off in the same location I'd flew for the past 13 flights, while it was in the air recording some footage, it encountered some errors and entered ATTI mode so it started to tilt all over the place so I started to panick and couldn't control it. A few seconds later it just lost connection. After few heart pounding minutes I heard It. Sparky came back.
After reviewing the footage and flight logs it encountered multiple yaw errors, switched to ATTI and drifted away. It started to descend when it lost connection and hovered near the ground for a minute before regaining GPS and started to RTH. Luckily it didn't hit any obstacles when all of this happened.
2018-1-4
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hallmark007
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The problem is your asking a question that is not directly covered by your manual, so to find out you have to look at the scenario by using other areas of the manual and try to piece together what should occur.

It’s all very well for dji Elektra to tell you it hovers go read the manual page 13, but page 13 does not cover this and neither does 14/15 , so unless she has other information we don’t know about or something that has been omitted from your manual, then you need to refer to other parts of the manual.

So first we know with gps,  loss of  radio signal will initiate RTH after 3 seconds. You hadn’t got gps , so what happens when you don’t have gps? Well your Aircraft goes into Atti mode, and what happens when your in Atti mode , your Aircraft drifts because it’s gps that holds Aircraft position in the air and this is no longer available.

So now we know this much, we must think logically,( what you are saying is if you have no gps and you lose radio signal) your Aircraft will somehow just hover and land, so how can Aircraft hover without gps? Answer it can’t .

If your scenario was possible then would it not be much easier to just switch off remote control when you go into Atti mode (Radio signal would be lost) and your aircraft would just hover, if this was possible then I’m certain this would be a failsafe that we would all know about. But unfortunately it’s not there , so we can deduce from the manual that if Aircraft is still in Atti mode it will continue to drift through propulsion and wind in the direction of downwind until it reaches 10% battery when it will go into critical landing immediately as our manual tells us.

I would certainly think that our manual should be much clearer in giving us information in such situations, unfortunately it doesn’t so we have to try to know every aspect of the manual to piece together probable outcomes like this, it sometimes leaves us to use common sense, but can cause confusion.

I believe your Aircraft drifted in Atti mode until it reached 10% battery and landed, this I can deduct from other cases I have seen and also the manual.
The hover without radio signal and no gps scenario is not one I’ve come across, and is nowhere in our manual.
2018-1-4
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Wachtberger
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hallmark007 Posted at 2018-1-4 04:50
The problem is your asking a question that is not directly covered by your manual, so to find out you have to look at the scenario by using other areas of the manual and try to piece together what should occur.

It’s all very well for dji Elektra to tell you it hovers go read the manual page 13, but page 13 does not cover this and neither does 14/15 , so unless she has other information we don’t know about or something that has been omitted from your manual, then you need to refer to other parts of the manual.

Perfect summary, thank you for that! From my own reflections I wish to add that it is probably correct that in such a situation Spark does nothing but wait in terms of flight commands, but at the same time its own propulsion and wind continue carrying it away because it has no way to hold it's position.
2018-1-4
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hallmark007
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Wachtberger Posted at 2018-1-4 05:07
Perfect summary, thank you for that! From my own reflections I wish to add that it is probably correct that in such a situation Spark does nothing but wait in terms of flight commands, but at the same time its own propulsion and wind continue carrying it away because it has no way to hold it's position.

Yes if it was a case of this happening on a windless day with no control input it would probably just hang around, or if controls were being pushed then orientation would change . Thanks for that.
2018-1-4
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heliman
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That sounds true. And it will either fly away or crash into something unless the pilot is in a position to bring it back.
Among possible resolves might be to either descend until vps is working or to ascend until gps is. But I don’t believe it does that.
2018-1-4
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Wachtberger
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heliman Posted at 2018-1-4 05:20
That sounds true. And it will either fly away or crash into something unless the pilot is in a position to bring it back.
Among possible resolves might be to either descend until vps is working or to ascend until gps is. But I don’t believe it does that.

Yes, and descending or ascending could be the wrong decisions as well depending on the situation. Thus I find it logical to be programmed for not doing anything by itself until the pilot can either regain control or the battery goes empty. Edit: Or until GPS comes back and it can RTH.
2018-1-4
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ADDvanced
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This is from Mike who runs www.phantomhelp.com

"The Spark never keeps flying until the battery is at 10%. That is a common misconception though. The Spark is only able to fly until the battery reaches the critically low level. At that point, it will start to auto land at its current location.

As for your scenario, the Spark was flying in ATTI mode. If the remote controller disconnects from the Spark while it's flying in ATTI mode, it will auto land at its current location. Since it was flying in ATTI mode, it would have drifted with the wind while it descended (hence my estimated landing spot)."
2018-1-4
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hallmark007
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ADDvanced Posted at 2018-1-4 12:12
This is from Mike who runs www.phantomhelp.com

"The Spark never keeps flying until the battery is at 10%. That is a common misconception though. The Spark is only able to fly until the battery reaches the critically low level. At that point, it will start to auto land at its current location.

Critical battery is 10%, the rest of your post makes no sense, but I’m sure you found it where mike who runs phantomhelp told you where it was.
If you already had the answers from mike who runs phantomhelp why ask the questions.

Mike from phantomhelp has offered no proof or logic as to what happened your drone. One question you should ask him why dji is hiding the fact that if you turn of your RC in Atti mode your aircraft will just land.
2018-1-4
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AlanIRL
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I guess someone needs to go into ATTI mode, switch off the RC and see what happens :-) Youtube Vid would be nice. But surely if an RC disconnect in ATTI mode caused the AC to land it would be common knowledge by now!
Although it does say in the manual that the AC will maintain its vertical height due to its internal Barometer in ATTI mode. So perhaps it can use the Barometer to make a somewhat controlled descent if it detects the RC is disconnected.
2018-1-4
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marlowe
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AlanIRL Posted at 2018-1-4 15:15
I guess someone needs to go into ATTI mode, switch off the RC and see what happens :-) Youtube Vid would be nice. But surely if an RC disconnect in ATTI mode caused the AC to land it would be common knowledge by now!
Although it does say in the manual that the AC will maintain its vertical height due to its internal Barometer in ATTI mode. So perhaps it can use the Barometer to make a somewhat controlled descent if it detects the RC is disconnected.

Where in the manual does it say that in ATTI mode the AC will maintain its vertical height due to its internal Barometer?
2018-1-4
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DJT_MVSP
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DJT_MVSP Posted at 2018-1-4 03:27
I learnt that from my experience; That's how it behaved when it entered ATTI and lost connection. That day, I took off in the same location I'd flew for the past 13 flights, while it was in the air recording some footage, it encountered some errors and entered ATTI mode so it started to tilt all over the place so I started to panick and couldn't control it. A few seconds later it just lost connection. After few heart pounding minutes I heard It. Sparky came back.
After reviewing the footage and flight logs it encountered multiple yaw errors, switched to ATTI and drifted away. It started to descend when it lost connection and hovered near the ground for a minute before regaining GPS and started to RTH. Luckily it didn't hit any obstacles when all of this happened.

It will auto land without positioning.
2018-1-5
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hallmark007
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marlowe Posted at 2018-1-4 21:37
Where in the manual does it say that in ATTI mode the AC will maintain its vertical height due to its internal Barometer?

That would be on page 9
2018-1-5
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marlowe
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hallmark007 Posted at 2018-1-5 02:52
That would be on page 9

Thanks Hallmark - but I don't see it there (V 1.6 of Spark user manual). I even did a word search on "barometer" and it is not there. On page 9 ATTI mode is described, but there is no mention of barometer or altitude stability. Which version of the manual do you have?
2018-1-5
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hallmark007
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marlowe Posted at 2018-1-5 17:17
Thanks Hallmark - but I don't see it there (V 1.6 of Spark user manual). I even did a word search on "barometer" and it is not there. On page 9 ATTI mode is described, but there is no mention of barometer or altitude stability. Which version of the manual do you have?

here it is im on 1.4 manual so maybe a different page sorry about that FEF8A320-DB27-4BC8-9310-46D6D1DDC95D.jpeg
2018-1-6
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heliman
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An obsolete manual proves nothing.
There might be a reason that section is changed.
Why knows why.
2018-1-6
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Jos A
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flying indoors with no gps-signal, spark holds his altitude
2018-1-6
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hallmark007
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heliman Posted at 2018-1-6 09:32
An obsolete manual proves nothing.
There might be a reason that section is changed.
Why knows why.

don't think the way barometer or barometric pressure works has changed, if it has look out for sparks falling out of the sky in your area soon.
2018-1-6
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hallmark007
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heliman Posted at 2018-1-6 09:32
An obsolete manual proves nothing.
There might be a reason that section is changed.
Why knows why.

This is what the new manual says notice the last sentence regarding horizontal shifting.

The aircraft will revert to ATTI mode when GPS signal is weak, or when the compass experiences interfer- ence where the Vision System is unavailable. In ATTI mode, the aircraft is easily affected by its surround- ings, which may result in horizontal shifting.
2018-1-6
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hallmark007
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Jos A Posted at 2018-1-6 09:50
flying indoors with no gps-signal, spark holds his altitude

VPS will hold altitude and position indoors.
2018-1-6
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Ahmed Hussain
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I think dji through it's firmware updates changing some issues a bit due to recent fly aways and other accidents.

Two days before, a friend was asking me for the reason that causes his spark landing once it reached 5-6 m altitude everytime!

I found it was because of compass calibration was needed. I think this procedure is new came with firmware 0900 to prevent fly aways. So it's a good precautionary process.
2018-1-6
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hallmark007
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Ahmed Hussain Posted at 2018-1-6 10:27
I think dji through it's firmware updates changing some issues a bit due to recent fly aways and other accidents.

Two days before, a friend was asking me for the reason that causes his spark landing once it reached 5-6 m altitude everytime!


thats not new, its a failsafe in all dji drones max height 16 feet with weak gps, in Atti  mode max height 30feet, although i haven't seen it mentioned regarding compass calibration.
2018-1-6
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Szikra
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One more important compass fact.
If there is a message to calibrate compass or move done, it is best to check compass interference level 1st.
If that is high, do not calibrate compass as you will calibrate it to the point you are in, and as soon as it takes off and moves, it will be out of calibration...
Better to move somewhere with no interference and it will just work..
You barely need to calibrate unless the drone is really confused...
Any opinions?
2018-1-6
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hallmark007
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Szikra Posted at 2018-1-6 15:31
One more important compass fact.
If there is a message to calibrate compass or move done, it is best to check compass interference level 1st.
If that is high, do not calibrate compass as you will calibrate it to the point you are in, and as soon as it takes off and moves, it will be out of calibration...

Yes your correct best to first move, calibration in that area could be detrimental. All your assumptions are correct.
2018-1-6
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Ahmed Hussain
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Szikra Posted at 2018-1-6 15:31
One more important compass fact.
If there is a message to calibrate compass or move done, it is best to check compass interference level 1st.
If that is high, do not calibrate compass as you will calibrate it to the point you are in, and as soon as it takes off and moves, it will be out of calibration...

That's exactly what I told him. He was trying to fly in a narrow passageway.
2018-1-7
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artie the z
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go to your flight record and you can follow your flight pattern i had a crash of unknown originand after half a day search went home looked at the flight record and went back to the site and lcated it in an hour
2018-5-19
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S-e-ven
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hallmark007 Posted at 2018-1-4 14:46
Critical battery is 10%, the rest of your post makes no sense, but I’m sure you found it where mike who runs phantomhelp told you where it was.
If you already had the answers from mike who runs phantomhelp why ask the questions.

Just  found this topic by looking how the Spark would behave, in  atti and no connection.
Seems still a misery.

Or is there some proven behavior reported, somewhere?


But to the critical battery, I can add something:
It is not just always 10%.
Like the Battery RTH is depending on the distance and height, the critical battery landing  is depending totally on the flight altitude.
10% it is, as long the bird is be able to get to the ground in 30 seconds or less, methinks
Which limit that 10 seconds critical battery to  about 50ish m height, I think

So in case the bird is "loosing it" in a +100m flight , the critical battery landing starts a bit earlier.
I had once one still near 100m and 15 or 16 % battery (out of memory)
Was surprising, since I thought I can cover distance and height better, before that starts.


2019-8-27
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JJB*
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Hi,
A Spark in ATTI and loosing contact with the RC will autoland after few seconds.
Not documented but it happens like this.

cheers
JJB
2019-8-27
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S-e-ven
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JJB* Posted at 8-27 06:02
Hi,
A Spark in ATTI and loosing contact with the RC will autoland after few seconds.
Not documented but it happens like this.

Thanks for the Info!
2019-8-28
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Phxbird57
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DJI Elektra Posted at 2018-1-3 23:31
Hi, sir. Please note that if the spark disconnect with RC over 3 seconds, it will trigger RTH when the drone have a good GPS signal. If spark has no GPS signal, it will hover. Please look at our user manual carefully, you can turn to page 13. If you have more doubt, please infom us.

Hello Elektra
Question along the lines of the topic.
I was flying my spark straight out and a warning came up " only enough battery to return to home " cancel or yes to go in to RTH mode. I was at 70% battery so I cancelled and when out farther. I lost signal and then was getting some info back. BUT the drone was just hovering. Now the question by me cancelling the RTH earlier did that cancel the RTH when signal is lost also?
Thank you in advance.
Phxbird57
2019-10-17
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S-e-ven
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Phxbird57 Posted at 10-17 15:07
Hello Elektra
Question along the lines of the topic.
I was flying my spark straight out and a warning came up " only enough battery to return to home " cancel or yes to go in to RTH mode. I was at 70% battery so I cancelled and when out farther. I lost signal and then was getting some info back. BUT the drone was just hovering. Now the question by me cancelling the RTH earlier did that cancel the RTH when signal is lost also?

to answer that for sure, someone would need to know the flight record.
But:
In case your drone told you at 70%, "only enough battery for RTH", and after you cancelt this RTH request and flew even further away, you drone CAN NOT do an RTH, with 69% or 50%, or xx% anymore.
Simple because more distance needs more battery. Since for the shorter distance was just enough juice left, everything after that, may just hover and land, where it hovers.
This way, you know where to search for it.
Starting an RTH, but have to land between that start and HP gets you in nowhere's land, for the location.

Aside that:
What is you RTH height? Even flying with sport and 50kph away, should'nt let the bird request a battery RTH on 70%
Unless it hast to rise quiet heigh (3-500m comes in mind. ;-), before it can start flying back with 36ish kph at RTH speed
2019-10-19
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Phxbird57
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S-e-ven Posted at 10-19 01:58
to answer that for sure, someone would need to know the flight record.
But:
In case your drone told you at 70%, "only enough battery for RTH", and after you cancelt this RTH request and flew even further away, you drone CAN NOT do an RTH, with 69% or 50%, or xx% anymore.

Thank you for your answer.
2019-10-23
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Phxbird57
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S-e-ven Posted at 10-19 01:58
to answer that for sure, someone would need to know the flight record.
But:
In case your drone told you at 70%, "only enough battery for RTH", and after you cancelt this RTH request and flew even further away, you drone CAN NOT do an RTH, with 69% or 50%, or xx% anymore.

I know that the auto popup notice is very conservative. It would be like driving your car to 70 of the gas tank and thinking can I make it back. answer is yes. Now unless with the drone you have a head wind it may use up more battery but in my case the wind was a cross wind. I've done this many times with a Phantom 3 adv. and made it back with battery to spare.  
2019-10-23
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