Nilesh-spark Posted at 2018-7-1 08:53
While I understand that there may have been a little wind, it was really not a very windy morning.  I did try to get control before using the RTH feature. I did try to bring it down, but it was all over really quickly. Loss of control, compass error, and drone out of sight - felt like under 10 seconds.

One more question. When did you use RTH feature? In what moment exactly? Several seconds after your AC started to be blown off?

I am asking because it will explain incessant beep of your RC.

Nilesh-spark Posted at 2018-7-1 08:35
This is a good question. I didn't understand that myself. It usually records the home point on take-off. I took off, and the home point was recorded a few seconds later.

Thanks to JJBspark for answering it in post #20.

Were you able to look at the video of the flight from your phone?

JJBspark Posted at 2018-6-30 23:08
Hi Prairie Chicken (oops, never saw one can we see a picture please? )

I think that DJI uses the same message for multiple situations.

Thanks for taking the time to inform a newbie at this. I kind of suspected as much, but thought I would point it out in case the answer was hiding in plain sight.

I don't know what it takes to get a picture in my avatar (that's a low priority for me), but this prairie chicken looks suspiciously like an Alpine white Spark. Clever shape-shifters, they are.

I won't take up any more of your time. I'd like to know what happened to Nilesh's Spark, too.

Prairie Chicken Posted at 2018-7-1 10:46
Thanks for taking the time to inform a newbie at this. I kind of suspected as much, but thought I would point it out in case the answer was hiding in plain sight.

I don't know what it takes to get a picture in my avatar (that's a low priority for me), but this prairie chicken looks suspiciously like an Alpine white Spark. Clever shape-shifters, they are.

Hi PC,

You are challenging my imagination, like a white spark....  

We all like to learn from each other on this forum, knowlegde is power and even better > safer flying!

cheers
JJB

JJBspark Posted at 2018-7-1 10:13
Hi Mirek,

I understand what you are saying, could be the case.

Yes - thanks JJB - please share your findings.

Nilesh did confirm now that he did push Auto- land. So I would lean towards the fact that at 1 m 4 s the AC was starting to land as directed by pilot and not because up-link was already broken.


At 1m 8s the signal was lost because of obstacle between Nilesh and the Spark - a lodge.

So, the events most likely unfolded as follows:
45.5 sec - compass errors
46.6 sec - Spark drops to ATTI due to compass, IMU and GPS misalignment. Spark starts moving with breeze at 33 m of altitude. At this point Nilesh is rotating Sparkclocwise  - Spark responds correctly. Connection OK.
49.7 sec - very short move forward and to the left on sticks. Lasts 0.5 sec. Spark responds correctly. Connection still OK.
50 sec - Spark is being rotated clockwise by Nilesh. It responds correctly. Connection still OK.
52.8 sec. - Nilesh instructs Spark to go up. Spark responds correctly. Connection still OK.
59.9 sec. - Nilesh instructs Spark to stop raising (Spark is at 41 metres now). Spark responds correctly. Connection is OK.

For the next 4 seconds Nilesh is not doing anything thinking about next step. No stick movements. Spark drifts with breeze.

1m 4s - Nilesh pushed auto-landing button. Spark responds correctly and starts to auto-land. Connection OK.
1m 8.5 sec - Connection finally lost - Spark is behind the lodge over 100 metres away. Lodge disrupts connection. Spark continues to drift and land.

Mystery solved.
Now:
Why we do not see RTH attempt? Because Spark in ATTI ignores RTH command.
Why do we see no reaction to switch to Sport mode? Sport mode helps when misalignment between compass/IMU/GPS is small. As described in other analysis, it seems that switch to Sport mode desensitizes Spark from small errors which may cause ATTI. In this case we probably witnessed large disagreement which could not be reconciled by Spark controller even in Sport mode. Hence Spark continues in ATTI.

In the end, as I suggested before, go for warranty claim and share with us what DJI said.

Mirek

Nilesh-spark Posted at 2018-7-1 08:36
Yes, I did. I went to the location and searched all over for 4 hours. Nothing.

Sorry to hear that, hopefully you will think of something.

Nilesh-spark Posted at 2018-7-1 08:53
While I understand that there may have been a little wind, it was really not a very windy morning.  I did try to get control before using the RTH feature. I did try to bring it down, but it was all over really quickly. Loss of control, compass error, and drone out of sight - felt like under 10 seconds.

At what height were you flying the SPARK.

The question: If you are here to describe that you did not calibrate the compass after you traveled to Africa and did not expect enough GPS signals to get your HomePoint, do you also get a warranty replacement?

djiuser_bC5M8YoiYr6N Posted at 2018-7-1 20:21
The question: If you are here to describe that you did not calibrate the compass after you traveled to Africa and did not expect enough GPS signals to get your HomePoint, do you also get a warranty replacement?

Well, firstly, I live in Africa, and I was travelling on a weekend away in our beautiful country. Also, it is South Africa, so we have pretty good GPS in general.  I was here to find out whether I would be able to recover my drone before leaving from our destination. If I get a replacement from warranty, because it was a drone issue, then that is great. Hopefully I did do everything right, and it wasn't human error.

Nilesh-spark Posted at 2018-6-30 08:00
Thank you. That is reassuring. I have logged a call, and I will await a response.

You're welcome. Let us know what is the update of your case.

S.J Posted at 2018-7-1 18:07
At what height were you flying the SPARK.

See my post #45 with analysis. Nilesh was flying at 33 metres when problems started.

Nilesh-spark Posted at 2018-7-1 21:03
Well, firstly, I live in Africa, and I was travelling on a weekend away in our beautiful country. Also, it is South Africa, so we have pretty good GPS in general.  I was here to find out whether I would be able to recover my drone before leaving from our destination. If I get a replacement from warranty, because it was a drone issue, then that is great. Hopefully I did do everything right, and it wasn't human error.

Nilesh,

How far away you were from your home (I mean your real home where you calibrated Spark's compass last time) when you lost your Spark? How many kilometres (approximately).

I am asking because many forum members believe that Spark's compass should not be calibrated if DJI GO does not prompt you to do so. DJI says so in Spark's manual.

I believe that this is not wise. I argue that compass should be re-calibrated when you move long distance from the position where you calibrated compass last time (perhaps few hundred kilometres). The reason for it is that geo-magnetic field where you fly Spark may have vastly different properties than geo-magnetic field where you calibrated Spark last time. Geo-magnetic field has three axis and varies in different places on Earth. It also can be affected by geological features and many other things.

As a matter of fact DJI is inconsistent with its advice. While they advise not to calibrate Spark's compass unless DJI GO says so, they advise something totally different for Mavic Air which is a very similar drone. For Mavic Air they advise to calibrate compass when you move 50 kilometres or more and when you did not use your drone for more than 30 days. I believe that this statement is correct - not the one in Spark manual.

Please let us know. In any case, as I said, I believe you have a strong case here.

Mirek.

Mirek6 Posted at 2018-7-3 07:33
Nilesh,

How far away you were from your home (I mean your real home where you calibrated Spark's compass last time) when you lost your Spark? How many kilometres (approximately).

Hi Mirek,  I was about 400km from home. The app did not request me to calibrate, and all seemed to be in order before I took off. I'm of the opinion that if the app does not tell me it requires calibration, I'm not going to calibrate (If it ain't broke, don't fix it.. right?).

Anyway, great news. It was a warranty issue, and they will be replacing my baby spark. So relieved.

Thank you everyone for your support, and assistance. You were all really helpful, and I'm so glad there is such a strong community of such intelligent people.

DJI Paladin Posted at 2018-7-3 02:29
You're welcome. Let us know what is the update of your case.

Anyway, great news. It was a warranty issue, and they will be replacing my baby spark. So relieved.

Thank you everyone for your support, and assistance. You were all really helpful, and I'm so glad there is such a strong community of such intelligent people.

JJBspark Posted at 2018-7-1 10:56
Hi PC,

You are challenging my imagination, like a white spark....  

Anyway, great news. It was a warranty issue, and they will be replacing my baby spark. So relieved.

Thank you everyone for your support, and assistance. You were all really helpful, and I'm so glad there is such a strong community of such intelligent people.

Mirek6 Posted at 2018-7-1 10:18
One more question. When did you use RTH feature? In what moment exactly? Several seconds after your AC started to be blown off?

I am asking because it will explain incessant beep of your RC.

For learning purposes... Yes.. So, I was busy getting the shot below, and there was some movement on my screen. I looked up, and it had started drifting. I tried to steer her back to position, but there was no response. Usually, my go-to strategy was to click it into sports mode, and back, and it usually regains control. I tried this, but no luck. It carried on going. As soon as it was out of sight, I hit RTH, but it was too late.

Nilesh-spark Posted at 2018-7-3 09:14
Anyway, great news. It was a warranty issue, and they will be replacing my baby spark. So relieved.

Thank you everyone for your support, and assistance. You were all really helpful, and I'm so glad there is such a strong community of such intelligent people.

You're welcome. Enjoy and always have a safe flight. If you have other concern, please don't hesitate to post it. We are happy to help you.

Nilesh-spark Posted at 2018-7-3 09:17
Anyway, great news. It was a warranty issue, and they will be replacing my baby spark. So relieved.

Thank you everyone for your support, and assistance. You were all really helpful, and I'm so glad there is such a strong community of such intelligent people.

Congratulations!

Nilesh-spark Posted at 2018-7-3 09:14
Hi Mirek,  I was about 400km from home. The app did not request me to calibrate, and all seemed to be in order before I took off. I'm of the opinion that if the app does not tell me it requires calibration, I'm not going to calibrate (If it ain't broke, don't fix it.. right?).

Anyway, great news. It was a warranty issue, and they will be replacing my baby spark. So relieved.

Nilesh,

Thanks for confirmation.

You say: "I'm of the opinion that if the app does not tell me it requires calibration, I'm not going to calibrate (If it ain't broke, don't fix it.. right?)."

I believe that DJI admitted their fault, and it was. indeed, their fault.
That saying you quoted does not apply here simply because, in my view, it was broken but DJI GO did not warn you - hence warranty case. While we are not 100% sure that the fault was due to uncalibrated compass while DJI GO did not recognize it properly before trouble hit - this is indeed extremely probable scenario. Your flight pattern did not display any other common issues which may have caused ATTI outside of disagreement between your magnetometer and gyroscope.

I do not trust DJI GO - it is very buggy.
But I trust science. And science explains how magnetometers work and why calibration is required when you travel long distances. Besides - as I mentioned - DJI contradicts themselves in Spark versus Mavic Air manual.

Again - thank you and good luck with your brand new Spark!

Nilesh-spark Posted at 2018-7-3 09:19
For learning purposes... Yes.. So, I was busy getting the shot below, and there was some movement on my screen. I looked up, and it had started drifting. I tried to steer her back to position, but there was no response. Usually, my go-to strategy was to click it into sports mode, and back, and it usually regains control. I tried this, but no luck. It carried on going. As soon as it was out of sight, I hit RTH, but it was too late.

Thank you again.

This is consistent with auto-landing which was started by you hitting RTH when in ATTI.

We cannot confirm such things 100% (DJI is not answering our questions) but we can learn from looking at logs and co-ordinating what we saw with testimony of people like you.

It is hard to test what happens when you hit RTH when Spark is in ATTI because it is hard to deliberately get Spark to ATTI (yes we tried - I discuss it with JJB in private messages - he is doing a lot of experiments like this which helps us to help others better).

Your case shows that this is most likely what Spark's firmware is programmed to do:
- when RTH in P-GPS - Spark returns home (if home point is set)
- when RTH in OPTI, Spark hovers (confirmed by JJB)
- when RTH in ATTI, Spark starts auto-landing (as in your case)

While we need more examples like yours to be 100% sure, I am right now fairly confident that this is the behaviour which DJI designed. And it does make sense.

Thanks for sharing and letting us learn.

Mirek

Love the in depth analysis here. Good stuff all.

Nilesh, glad to here you'll be back in the air before too long.