I started to write this post yesterday then I aborted it due to adrenaline shacking my body after my first serious incident with Spark.

Circumstances:
It was a quiet late afternoon and I was washing my car in the garden.
Weather was just fine with a little seabreeze coming from west to east. (this is important relatively to what is in the log)
Pilot awareness was poor, I was doing carwashing then I gave a look at the sunset and I thought let's take the baby off and take some shots.

Facts:
I took off two or three meters away from the usual spot I usually take off from which was occupied by the wet car.
This spot is in the middle of two residential houses, mine that is a two level house and a three level building eastwards.
I immediately noticed a delay in Gps connection (later thought make it obvious because I was more inward in the garden than the usual spot)
anyway I took off with gps loched and about 7 or 8 satellites linked.
I usually go to about 10 15 ft to make controls check, and last checklist items then I sent it up to about 130-140 ft.
I can swear I saw the green "homepoint recorded" tag even if it doesn't show up in the replay.
Antennas where correctly parallel to the ground having the drone at my zenit.
Accordingly to replay home point was instead recorded when aircraft already took off and probably after controls check when the aircraft gained altitude and, I assume, locked more Gps satellites.
Reached the altitude i started shooting couple of AEB's and couple of panoramas.
There was a discrete latency between every shots, a panorama was also aborted due to "camera error".
Connection with rc was never lost and just occasionally the issue was weak signal transmitting.
At this point the aircraft started to drift eastward very slowly like kissed by the seabreeze.
I tried to adjust and I found controls not responding and drifting continued and things start to happen very quickly.
Led in the Rc became red and application crashed.
Aircraft went out on my sight I reloaded the App which engaged a tutorial!, and rc beeped as return to home has been engaged.
I went out from my garden and I do not see the aircraft anymore.
I run across the block and aircraft was missing.
Disappeard.
Walking back home I took the tutorial and launched again the app, and I tought at same point I was allucinating because I saw the rc led green again and suddendly red again in three or four footsteps.
I launched the find my drone app and it flashed the craft was behind the building next to my house.
I knocked neighbors and we didn't find it, so after some research I thought of a flyaway.

This is the flightlog:
http://www.phantomhelp.com/LogViewer/HSXVEL5GC3QLDBP7Y0EZ/

I have seen many logs here and with my experience I can say there are many not to do things but also some this should no happen.
-First of all I took off with only 7 sats. (even I would argue that gps symbol was full locked and green tag ready to go appeared)
-First event of the log is at sec 14.8 after controls check and checklist is GPS position no match. (This didn't appear as a warning on the device screen and this SHOULD NO HAPPEN!)
-Second event is RTH record 20 secs into the flight at 54ft height. (there is a pilot to blame for this, I guess)
-Third event is downlink restored when aircraft was hoovering and probaly shooting. (this is not a loss of connection with the rc but the latency in the picture shooting).
-Other downlink of a few second occurs in sequence while the aircraft started hoovering.

I would be glad to hear some opinions on it, today when adrenaline is down and I discovered why everything happened, a stupid reason I will disclose in a post which will follow if interested.

The aircraft was recovered in the backgarden of the three story building on a gazebo roof 5 cm from the wall, I got there with the Ipadpro with the find my drone app and didn't find it the first try because was over the gazebo roof above our heads. Just got a few scratch on one propeller, probably was hoovering there due to the not certain rth point or because just landed since was engaged when was on my vertical more or less. No sign of the rth in the log and I am not sure if it was engaged first or later than the app crash.

By the way I posted a shot I took to celebrate happy ending. I f you missed it you can

Glad to see that you got it back..   The disturbing part of the log is that you were having connection problems only 140 feet up while using the RC.  I think the remainder of your problems can be explained.  You took off with what looked like a good GPS lock but it  was not quite good enought and the home point did not get recorded until you were a small distance away from you.  That home point might have been over the gazebo that it ultimately landed on.  Your poor connection eventually triggered an automatic return to home and the craft did just that. Just home was not where  you expected it to be.  
I don't know what to say to help you.   Possibly there was too much Wifi interference where you were flying.

LouisP Posted at 2018-1-30 14:55
Glad to see that you got it back..   The disturbing part of the log is that you were having connection problems only 140 feet up while using the RC.  I think the remainder of your problems can be explained.  You took off with what looked like a good GPS lock but it  was not quite good enought and the home point did not get recorded until you were a small distance away from you.  That home point might have been over the gazebo that it ultimately landed on.  Your poor connection eventually triggered an automatic return to home and the craft did just that. Just home was not where  you expected it to be.  
I don't know what to say to help you.   Possibly there was too much Wifi interference where you were flying.

Fair analysis, I blamed myself for the poor gps lock later. And sometimes I blamed fellow pilots for doing that. Anyway the cause is much more stupid you will find when I will disclose it. What I am scared of, is that the GPS error in the log didn't come out in the app. This would have me landing ASAP .Correct the RTH interpretation, anyway landed not even on the officially  recorded one, but we were in the 20mt radius.

PS : I forgot to say spark was found capsized with battery fully discharged.

Looking at your log nothing looks strange here, yes you had weak gps taking off, but everything from there looks fine, there is a major part of your log missing I don’t know why.
There were a couple of downlink errors but none of these lasted longer than 3 seconds so Aircraft won’t go into RTH mode, nothing else on log shows any problem.

Two things I would say 1/ it looks like you took off from a roof top these launching areas can be a source of a lot of interference and are not ideal.
2/ to fly with gps lock you need 6 satellites, your spark uses both gps and glonass because you see 7 sats doesn’t mean you have enough to get position lock you could very well have 4 gps and 3 glonass , to fly you need minimum of 6 of either gps or glonass , so the guaranteed number to fly is 11 thus guaranteeing you have minimum 6 of one type.

I don’t know if you can recover more of the flight log that might explain what happened, if you can it might explain a bit more.

hallmark007 Posted at 2018-1-30 15:11
Looking at your log nothing looks strange here, yes you had weak gps taking off, but everything from there looks fine, there is a major part of your log missing I don’t know why.
There were a couple of downlink errors but none of these lasted longer than 3 seconds so Aircraft won’t go into RTH mode, nothing else on log shows any problem.

The log comes as is. I took off on the ground as usual just three meters more into the garden than I took off hundreds of times. Probably the log ends when the app crashed but  RTH has been engaged earlier and  rc beeped. I wonder, and don't know if it is usual, why the gps error was not reported on screen. I was wondering if a copy of the log might be on the sd .

Enri Posted at 2018-1-30 15:28
The log comes as is. I took off on the ground as usual just three meters more into the garden than I took off hundreds of times. Probably the log ends when the app crashed but  RTH has been engaged earlier and  rc beeped. I wonder, and don't know if it is usual, why the gps error was not reported on screen. I was wondering if a copy of the log might be on the sd .

Gps no match was recorded on log but for a very short time and homepoint was recorded, there will be a dat file in your black box of your aircraft it’s a very large file and you will need to get someone from dji to down load it.

hallmark007 Posted at 2018-1-30 15:41
Gps no match was recorded on log but for a very short time and homepoint was recorded, there will be a dat file in your black box of your aircraft it’s a very large file and you will need to get someone from dji to down load it.

Good to know thanks.

hallmark007 Posted at 2018-1-30 15:41
Gps no match was recorded on log but for a very short time and homepoint was recorded, there will be a dat file in your black box of your aircraft it’s a very large file and you will need to get someone from dji to down load it.

Good to know thanks.

Today I took off with 9 satellites and the green ready to go icon it lost connection a little bit and came back. So lesson is never take off with too little satellites?

Enri, please take off your drone with good GPS signal and glad that your drone was back. Please note that the drone needs over 6 satellites to record the home point before taking off. Thanks for your support.

Take off from a roof of a building is not recommended

You did get lots of disconnections and I think its this is error of wrongly set wifi channel. Because when you get disconnections with such low distance to aircraft it will be much worse further, so best thing to do is land it.
Once I had close situation like this, except i got much more sat locked up. Got first disconnection in 5meters or so and of course didn't let it anywhere far to fly. It was also drifting sideways and I was just curious what happens next. Aircraft was continuing of loosing connection to RC. So I just landed it. I did wifi scan in that area, with wifi analyzer app, it didn't show very crowded channels there. Weird, only thing that we can see is that drone is extremely sensitive to all kinds of interference.

Anyway glad that you retrieve the AC and lesson learned in a good way. Builds confidence and intelligence in future flight. Congrats for that.

Thank you for sharing your experience and happy to read that you have found your Spark after all!

Good thing you got it back...

Your flight log is funy rather than a strange one.

In spite of weak GPS and AC drifting, yet no records shows ATTI mode!

All ATTI recordes were dropped from the flight log file.

Ahmed Hussain Posted at 2018-1-31 10:52
Your flight log is funy rather than a strange one.

In spite of weak GPS and AC drifting, yet no records shows ATTI mode!

It absolutely did not enter in atti mode...

Enri Posted at 2018-1-31 12:26
It absolutely did not enter in atti mode...

As I said: Funy!  

But I doubt!

CASE SOLUTION:
Connection was literally jammed due to almost full sd card.
When started shooting the pano I noticed the delays....but the rc was always green and aircraft responding.
Until App went probably crazy due to the intensified traffic allocating the space for the shots and finally crashed.
Log is truncated here.
From data on the spark I then desumed.
I re engaged the application in the same exact time RC lost connection too.
Aircraft went behind the building very close to his wall and triggered RTH. RC beeped.
Being in a 20 mts radius from the home point aircraft started hoovering.
At the same time I was running behind the building and lost connection with RC.
It took a while because the app pretended I take the tutorial before I could run it again.
The find my drone function indicated the exact spot where the aircraft landed I found over a gazebo capsized with 0 battery level.
Probably waited and then hit slowly the wall and fall to the gazebo trying to land.

LESSON:
Check always video cache settings and SD card capacity don't use more than  66% capacity.
If you are in usual spots and you find any interference for the first time land asap.
Close and reload before your flights the Ios App and start with a fresh launch because if it is updated the first time asks for tutorial...

Nice pic, and I'm glad you recovered your Spark. Spark incidents are growing, I believe this is due to the awareness of issues that are being shared. Check out UAVFlyaways.com

It's a new site keeping track of fly away issues, it's sort of like this DJI Forum but more vendor neutral. You can share your experience with UAVFlyaways and possibly help others.