Active Track "Fly Away" of $400 Spark - Not Happy
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4962 110 2017-12-19
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Bright Spark
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The spark issued repeated warnings.In any flying incident, ignoring warnings is down to you.
2017-12-20
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RepKK
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From a first person perspective let me add these things.  First,  we don't have skyscrapers in Springfield.  The tallest building is 13 floors and that pretty much stands alone.  Especially at 160 feet.  The City Hall is only 4 stories.  I also made first pass around clock tower with no incident.  As I have said before... I have flown around the non-clock tower end of this building a week ago and around my 18 acre farm and EVERY TIME (sorry for the emphasis... i promise I am not yelling) I have received high-wind warnings.  I have taken 36 flights with Spark since opening it two weeks ago, everyone that has been outside has alerted me about wind.  Honestly... everytime.  I have done wonderful sphere shots of my farm at 300 feet and during the 47 photos being taken, I get the warning about wind.  The Spark has always been a champ.  I have never lost GPS signal while flying (even on this fly away) and the Spark has stayed rock solid.

I can tell you that even when I felt it was windy (again it has always given me a warning on each flight), I have never had to use the joystick to keep the Spark in position.

Somebody asked why I was pushing to the right during the Active Track.  I was not using one of the "Quick Shot" pre-programmed shot.  I was in Active Track only which allows the pilot to control the drone while the AC attempts to track the object selected.  This is a great feature and by using  pushing to the right the AC stays the same distance from object and will do a complete circle around it.  Even better, I took a picture of my son running in an open field and while I start behind him... he takes off and the drone circles around him and ends up flying along side him as he and the AC gains speed.  A very cool effect.  Anyhow that is why I was pushing right - and you can see that during my first pass around the clock tower (and I am pushing right making a very nice circle and didn't use forward motion to keep the AC in place).  

I believe when I backed off in distance staying at around 160 (far above all other nearby buildings) to get a not so up close shot... I was under that same conditions as before (again up high enough that other buildings should not be a factor.

Again, I have flown around the other end of this building before (when I first got the drone).  I made one very nice pass around the clock with no incident.  It was after it lost that active track object and I re-aquired that things started going nutty.  I completely accept the wind concerns but I get wind notification every time I have flown (I can't remember ever not getting a warning).  

I thank everyone for the input here.  I must repeat that I like the Spark.  Not trying to bash their product.  Not trying to argue with anyone here.  In all my flights I have not seen wind push the Spark backwards (especially not at 28mph in the reverse direction).    I have seen plenty of videos now of DJI products going 28mph in reverse direction during Active Track though).

Springfield does not have a big (tall) downtown.  The wind is probably actually worse at lower altitude than 160 which is above all buildings.

Again, thanks for all the input to this point. I am learning a lot from your input.   
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RepKK
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DJI Elektra Posted at 2017-12-19 23:59
Hi, Rep. If you have any doubt with your case. Please inform us, I would help you look into it. Hope it can solve soon. Thanks for your patience.

Thanks for watching this post.  I appreciate the attention by DJI at this point.  I only waited on hold during the initial call for 5 minutes max (I thought it would be longer).  That person connected me to someone that handles these issues.  They answered right away.  They took my information, told me over the phone how to sync flight records and took enough info to get me an email to report rest of info (that email came within 1/2 hour of call).  I returned the email when I got off work and then received a response email within another 1/2 hour letting me know they would review and I would hear something within a few days.  DJI has been very responsive up to this point.

I still believe I was up high enough to be clear of any strange winds (this would be more obvious if I had the SD card from the AC (no I didn't cache stuff to phone because of memory overload on phone)).  I also note the success of the first pass with absolutely no issues.  Only change is that I backed off the clock tower by about 40 feet for the second pass.

As an Administrator here, thank you for you attention.
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RepKK
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JJBspark Posted at 2017-12-20 01:16
Interesting flight record to analyze. What i do not understand is the Controller max right input for long period in active track mode.All input should be zero because its a automated flight, isn`t it ?

JJBspark, I am not using a "quick shot" circling shot.  I am using Active Track which tracks the individual movement as I polite the AC.  If you are tracking a non-moving person (or in this case a non-moving building), moving the AC to the right basically circles to the right or left around the object.  

This can also be used to fly along side someone while in Active Track and the AC cameras stays on the individual while you pilot hard right or hard left to go along side them (I did this with my son running full speed in a field and I created a great shot as I flew right along with him).
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Bright Spark
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I think you are responding very sensibly.
I have had my share of unexplained events, but as I progressed? I see that most or all  of them have been down to me.
It is a marvellous machine, but  to draw an analogy the purchase of a piano does not bestow on the buyer  the ability to play it.
I really  hope you can recover your spark.
Unfortunately if you fly model aircraft, you will lose some.
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RepKK
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Bright Spark Posted at 2017-12-20 02:51
Anyone know what is the height of city Hall?
That's where event occurs.

It is four stories with a fence around the top to protect the mechanicals.  It does however sit down is a hole in the core block so it is more like 3 stories with a fence around the top.

No where near the 160 feet of the AC
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Wachtberger
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RepKK Posted at 2017-12-20 04:47
From a first person perspective let me add these things.  First,  we don't have skyscrapers in Springfield.  The tallest building is 13 floors and that pretty much stands alone.  Especially at 160 feet.  The City Hall is only 4 stories.  I also made first pass around clock tower with no incident.  As I have said before... I have flown around the non-clock tower end of this building a week ago and around my 18 acre farm and EVERY TIME (sorry for the emphasis... i promise I am not yelling) I have received high-wind warnings.  I have taken 36 flights with Spark since opening it two weeks ago, everyone that has been outside has alerted me about wind.  Honestly... everytime.  I have done wonderful sphere shots of my farm at 300 feet and during the 47 photos being taken, I get the warning about wind.  The Spark has always been a champ.  I have never lost GPS signal while flying (even on this fly away) and the Spark has stayed rock solid.

I can tell you that even when I felt it was windy (again it has always given me a warning on each flight), I have never had to use the joystick to keep the Spark in position.

You have found an intreresting variation of using active track. Very creative indeed and I can see the benefits now. Thank you for sharing it!
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Bright Spark Posted at 2017-12-20 05:11
I think you are responding very sensibly.
I have had my share of unexplained events, but as I progressed? I see that most or all  of them have been down to me.
It is a marvellous machine, but  to draw an analogy the purchase of a piano does not bestow on the buyer  the ability to play it.

Bright Spark, thank you.  I unboxed this baby just two weeks ago... and I am learning.  

I guess being December in Ohio, I should expect it to be windy.  But it has literally giving me a "high wind" warning on every flight that I can remember.  I took off on my very first flight in ATTI mode (outside my garage) the first night I got all the firmware updates done.  And remember thinking: "This is horrible" because it didn't have GPS lock and was drifting all over the place just hovering 8 feet off the ground.  It was night time so I didn't fly but for more than a minute or two.

The next day I took out and got GPS lock before taking off and they thing was just wonderful.  And sorry for stressing it... has done well ever since with multiple wind warnings on every flight I can remember in the 36 flights taken.

I thank all the youtube folks who have put out great videos that have helped me before I even opened the box on this thing.
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Bright Spark
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Well you never will have to use the joysticks to maintain position, unless you lose gps. It does it all for you.
In general if it does have to cope with a wind that equals its top speed you can't apply anymore bank to move forward anyway, regardless of stick input.
Not saying this is your situation, but I don't get wind alerts at under 15 mph wind, my max, at flying height.
Trying to gauge wind speed  by the horizon in sport mode, side on to the wind, is quite revealing.
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Wachtberger Posted at 2017-12-20 05:40
You have found an intreresting variation of using of active track. Very creative indeed and I can see the benefits now. Thank you for sharing it!

I hope to post a short clip of my son running... it is awesome and I "hope" to use it with a horse at full speed... I just need a/my spark back!!
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RepKK
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JJBspark Posted at 2017-12-20 01:16
Interesting flight record to analyze. What i do not understand is the Controller max right input for long period in active track mode.All input should be zero because its a automated flight, isn`t it ?

JJBspark,

Can I ask you what software you are using to get pitch and roll data from CSV file?
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RepKK
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JJBspark Posted at 2017-12-20 01:16
Interesting flight record to analyze. What i do not understand is the Controller max right input for long period in active track mode.All input should be zero because its a automated flight, isn`t it ?

JJBspark - Can you please post the page of this analysis for the last few seconds of the flight so I can see the pitch and roll of the plane as it was in reverse at 28mph?
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S.J
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RepK Posted at 2017-12-19 15:11
Actually, at 3:52 into flight I believe the Spark was attempting to fly away (while active tracking to the right)... if you watch my joystick (I didn't realize it at the time but) I am increasing the forward motion on the Spark to keep it from moving backward).  I was looking at the screen and thinking "Am I moving backward?".  I keep pushing forward until at 100% (this is not the wind).  At 4:07, I make the mistake of letting off the joysticks because I realize something odd is happening and the Spark is moving out of line-of-site despite my full intention of keeping it close.  That is when it shoots backward at 28+mph.  Then it was gone!!!

The biggest mistake is you did not set the home point manually on take off.  90% of the cases are human error.  These things are sophisticated and you need to do a bit of programming before  the SPARK does the job well.

Even though there is a high wind, the SPARK will defintley do an RTH not fly backwards  !!!
2017-12-20
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hallmark007
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Hi looking at your log although you say you stoped pushing on sticks at 4.08, log shows you were pushing on elevator banking aircraft to its right almost 100% from 4 .08 until 4.36 sec at 4.37 you lost downlink until 4.41, it was here that Aircraft took off, because of speed increase above 14mph which is top speed in auto modes except tripod, to almost 30mph it is almost certain you lost gps and aircraft was in Atti mode or had a problem with compass and Aircraft went into Atti mode causing aircraft to drift on the wind and most likely hit the building Lyons90 pointed out.

It’s very hard to see little gps graph in your video to see if lights went out this would be the first sign to say you lost gps but in the video it looks grayed out but I’m not sure.

While there was not warning that you lost gps or went to Atti mode the end of the log came quickly.
The reason your log finishes so quickly usually means a crash has occurred the last couple of seconds will not be recorded because data processing will be a couple of seconds behind so is not processed right up to crash.
Why you didn’t get warnings quicker is a bit strange , this one will be up to dji to decide if you get a warranty, I wish you luck.

PS: other explanation ie a huge gust came along and blew your aircraft straight back, but I don’t think this happened.
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RepKK
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S.J Posted at 2017-12-20 08:42
The biggest mistake is you did not set the home point manually on take off.  90% of the cases are human error.  These things are sophisticated and you need to do a bit of programming before  the SPARK does the job well.

Even though there is a high wind, the SPARK will defintley do an RTH not fly backwards  !!!

S.J - not sure what you mean here.  As the video shows...it clearly sets Home Point and a RTH altitude of 49M at 0:03 seconds into the flight. The green message comes up and tell me just that. The little green "H" shows that it never changes the Home Point to anything else.  If there is something else I should have done... please let me know.  I guess I assume as I have used RTH in other cases that when it set "Home Point Recorded RTH Altitude 49m" that it has indeed set the home point.

I agree with you of course.  If it lost contact with me it should (and it has on a couple of previous flights) did RTH.  But in this case I believe something else happened.
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RepKK
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hallmark007 Posted at 2017-12-20 08:55
Hi looking at your log although you say you stoped pushing on sticks at 4.08, log shows you were pushing on elevator banking aircraft to its right almost 100% from 4 .08 until 4.36 sec at 4.37 you lost downlink until 4.41, it was here that Aircraft took off, because of speed increase above 14mph which is top speed in auto modes except tripod, to almost 30mph it is almost certain you lost gps and aircraft was in Atti mode or had a problem with compass and Aircraft went into Atti mode causing aircraft to drift on the wind and most likely hit the building Lyons90 pointed out.

It’s very hard to see little gps graph in your video to see if lights went out this would be the first sign to say you lost gps but in the video it looks grayed out but I’m not sure.

hallmark007 Up to this point I have only been reporting on what I see by the Flight Record video that my phone produced.  At others suggestion mainly because I do not know what is stored in the phone and how to look at it... I posted the .txt file that you guys know how to look at.  It is interested to see that it goes well past the 4min 11seconds that is on the video generated by the DJI GO 4 app.

I do not have the software to see what many of you experienced guys must be seeing that shows what I was doing.  I can tell you that when I saw it on the video and with my eyes moving away from the clock tower I was tracking I was not thinking about remembering what I was doing.  I was thinking.... "what happened?"
When I talk about the joysticks - I have been strictly going off what the video shows I was doing up until 4:11.  Again, I wish I had the software to see what you guys are seeing and I am sure DJI support will be doing the same.  If there is a spreadsheet/excel file that someone can generate and post here for the time after 4 minutes that would be great (one that shows pitch/roll and what the joysticks were doing).  I am not seeing any of that and would love to.
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RepKK Posted at 2017-12-20 11:38
hallmark007 Up to this point I have only been reporting on what I see by the Flight Record video that my phone produced.  At others suggestion mainly because I do not know what is stored in the phone and how to look at it... I posted the .txt file that you guys know how to look at.  It is interested to see that it goes well past the 4min 11seconds that is on the video generated by the DJI GO 4 app.

I do not have the software to see what many of you experienced guys must be seeing that shows what I was doing.  I can tell you that when I saw it on the video and with my eyes moving away from the clock tower I was tracking I was not thinking about remembering what I was doing.  I was thinking.... "what happened?"

If you just click into your phantomhelp log just click on csv, file will download and all your flight info is there.
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RepKK Posted at 2017-12-20 08:28
JJBspark - Can you please post the page of this analysis for the last few seconds of the flight so I can see the pitch and roll of the plane as it was in reverse at 28mph?

Hi RepKK,

See 3 screenshots, one at 71% batt level (drone in control i guess (speed minimum)) + last records + summary.
Cheers JJB
analysis64.png
analysis70.png
summary.png
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RepKK Posted at 2017-12-20 08:09
JJBspark,

Can I ask you what software you are using to get pitch and roll data from CSV file?

At the moment writing my own analysis program....when its fully tested and i am happy i will publish it
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I wouldn't be fliying a drone around government buildings!!  Bad news!!  I think this one is the cause of bad judgement and environmental, due to high winds between buildings.
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hallmark007 Posted at 2017-12-20 11:42
If you just click into your phantomhelp log just click on csv, file will download and all your flight info is there.

hallmark007

THANK YOU!  Now I can see what others are seeing.

As a "retired" software engineer from the 80's this is all interesting.  I know I am probably jumping to conclusions but this sort of says what I thought all along.  When i was in Sport Mode traveling fast to the clock tower my pitch was around a -30 degrees (and you can see I was totally telling it to do that).

But at approx. 4min and 41 seconds the pitch goes opposite to extremely postive to about +14 degrees without my using the joysticks (I "think" that is what I am seeing)... as the AC goes from what I believe is 13mph sideways to 28mph backwards?  With no GPS loss.

I don't believe that the wind "pitched" this thing backwards and then made it accelerate too?

Again thank you for helping me see what others are reporting to me (I think I can see now that the video is way off time-wise to this table).
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and the graph of this flight, btw the distance and speed are metric values (kmh and meter)
graph.png
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lsufan861 Posted at 2017-12-20 12:07
I wouldn't be fliying a drone around government buildings!!  Bad news!!  I think this one is the cause of bad judgement and environmental, due to high winds between buildings.

While I agree... I was trying to get a shot of the 150 year old historic building and had no plan to go near government buildings.  But I understand your point.
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RepKK Posted at 2017-12-20 12:11
hallmark007

THANK YOU!  Now I can see what others are seeing.

Because it went from 13mph to 28mph only 3 things could have happened
1/ massive gust of wind , I don’t think this happened
2/ pilot switched to sport and flew backwards, I know this didn’t happen
3/ your Aircraft went to Atti mode, this is the most likely case.
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JJBspark Posted at 2017-12-20 12:00
Hi RepKK,

See 3 screenshots, one at 71% batt level (drone in control i guess (speed minimum)) + last records + summary.

JJBspark - wow... lots of data thanks.  I finally figured out how to use the .CSV file.

Your tables show what I am now seeing.  Don't you find it odd that in the last 4-5 seconds the pitch (without input from the RC) decides to go to +14 degrees and accelerate away without losing GPS?

I can understand the AC pitching forward (negative) and working to stay in place... or getting overwhelmed by the wind and moving away.   But pitching up (positive)  is a sign, to me, of this Active Track Flyaway that others are seeing.  Again, all without RC telling it to do this.

Don't you agree that the AC should have at least been pitching down to hold position? (please understand I am truly asking and not arguing).
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hallmark007 Posted at 2017-12-20 12:40
Because it went from 13mph to 28mph only 3 things could have happened
1/ massive gust of wind , I don’t think this happened
2/ pilot switched to sport and flew backwards, I know this didn’t happen

hallmark007 Thank you for your help and insight from over 1/2 million feet/meters of flight distance.  Wouldn't the table you helped  look at have say that during the 5 seconds it was flying backward (like no "GPS" reading of 15?
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RepKK Posted at 2017-12-20 15:37
hallmark007 Thank you for your help and insight from over 1/2 million feet/meters of flight distance.  Wouldn't the table you helped  look at have say that during the 5 seconds it was flying backward (like no "GPS" reading of 15?

Well if you look at it this way.

4.41 downlink restored aircraft moving at 13mph
4.42 Aircraft now moving at 20mph with no stick movements, increased to 28mph , log ends

So if there is no stick movements and you have gps 15sats then Aircraft should stop.
It can’t go any faster than 14mph in auto mode, but yet it’s moving at speed up to 28mph, question how can this happen . Wind ( I don’t believe this happened) so the only other way is if Aircraft went into Atti mode.
I know you say it showed 15 sats so in earlier post I asked if bar graph was showing 4/5 bars lit up, I couldn’t see in your video, but it looked grayed out and if this was the case then it doesn’t matter if you are seeing 15 sats if bars are grayed out your Aircraft is in or going into Atti mode, in other words correct measurement of satellites is the bar graph.

What we don’t see in the log is the end of flight, this is because data was not downloaded before crash, although I’m just guessing I believe that if aircraft had not have crashed so soon then we would have seen some warnings concerning gps.

I can only go on the info we have and try to assume what happened.

But I will put the question back to you , what would cause your aircraft to reach such speed without input from controller?
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hallmark007 Posted at 2017-12-20 12:40
Because it went from 13mph to 28mph only 3 things could have happened
1/ massive gust of wind , I don’t think this happened
2/ pilot switched to sport and flew backwards, I know this didn’t happen

ATTI mode?  Where is the data notice to the pilot that it is in ATTI mode.  He had a notice that it has a 28mph ground speed so,...
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hallmark007 Posted at 2017-12-20 16:21
Well if you look at it this way.

4.41 downlink restored aircraft moving at 13mph

"So if there is no stick movements and you have gps 15sats then Aircraft should stop.
It can’t go any faster than 14mph in auto mode, but yet it’s moving at speed up to 28mph, question how can this happen . Wind ( I don’t believe this happened) so the only other way is if Aircraft went into Atti mode."

I disagree that the aircraft should stop when you let go of the sticks with 15sats,...and it is active tracking.  Notice it is back in active tracking.  As long as it can see its target, all is good.  It doesn't care what its ground speed is and it isn't trying to hold a ground position but only a camera view of the target.

Active track is a flight mode.  It is not locked into a GPS position.  It can't be.  It is instead locked onto a camera view.  I think it was actively tracking a great view of a target (clock or ?) and didn't care that it was blowing away at 28mph.  The clock had to be a pretty small target at that range with that wide angle lens.

If that 3m 53.1s to 4m 45.2s data set posted is right, I don't understand how it returned to active tracking after losing track and dropping back to P-GPS.
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RepKK
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hallmark007 - I believe I am suggesting this....



and this...



I think the top of the building got in the way and it got crunched up there somewhere at 28mph.  This is what I am beginning to believe more and more.  I guess I am calling it the fourth option.

I have had plenty of communication from DJI... and hoping to get a response soon (they have emailed be three times asking for information over the last 24 hours).
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Madwand
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I'm guessing where you lose your case is when it said high wind, keep your eye on the drone.  Because you clearly didn't. DJI doesn't care about anything else that happened.
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RepKK Posted at 2017-12-20 18:00
hallmark007 - I believe I am suggesting this....

https://youtu.be/KR7o_EaS9wc

Wow, that definitely looks like a 4th option!
Please keep us updated with DJI's response.

Side note: surprised how well the camera records when going backwards at the speed
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Spenkelini Posted at 2017-12-20 00:10
Were the prop guards mounted on the Spark?

No prop cards.  They are still in the wrappers.
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Wachtberger Posted at 2017-12-20 05:40
You have found an intreresting variation of using active track. Very creative indeed and I can see the benefits now. Thank you for sharing it!

Wachtberger - Here is some Active Tracking I did during the weekend.    I have Active Track on and am piloting the drone to the hard right or left depending on the shot.   I am a newbie and thought this was something everyone does... (seriously I am not the first right?)

Others should notice the strength of the wind on the bush near the rocks.  I am using Active Track the whole time and the wind is pretty wicked on our farm (I would say stronger than downtown area).  Never a problem with the wind blowing it 28mph here that I can see.

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Madwand Posted at 2017-12-20 18:04
I'm guessing where you lose your case is when it said high wind, keep your eye on the drone.  Because you clearly didn't. DJI doesn't care about anything else that happened.

I kept my eye on it until it took off in reverse at 28mph
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LouisP
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RepKK... I do understand what you were doing... active track and hand flying is a great feature and I do that myself.
This has been gone over on here with a fine toothed comb and we still don't know what happened..  Let us hope DJI figures something out.

I still think the wind was the problem but maybe not the only problem.  Spark can handle pretty strong wind and should have been able to cope with what you were getting.

You may have stumbled onto a new bug when using the smart camera features in strong wind.  I think that it could be that when the spark is trying to stabilize the video for things like active track or tripod mode it may reduce the crafts ability to pitch and roll in order to get better video.  If that is the case, it would also limit the ability to fight wind as well as it normally would.

Your spark did not go into ATTI mode so it had good gps and good IMU. It should have known that it was moving without being commanded to move.  
All of this is conjecture at this point, but if true then the spark should have exited the active track when it sensed that it was not able to maintain its position.
2017-12-20
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Todd in Chicago
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JJBspark Posted at 2017-12-20 12:04
At the moment writing my own analysis program....when its fully tested and i am happy i will publish it

Cool!

Please let us know!  :-)

Cheers...

Todd in Chicago
2017-12-20
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Madwand
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RepKK Posted at 2017-12-20 18:23
I kept my eye on it until it took off in reverse at 28mph

That's hard to believe from the distance you were from it when it happened.  I can hardly see mine when it's a few hundred feet away.
2017-12-20
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S.J
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Flight distance : 322454 ft
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one option while you had your feeling the Spark was out of control is to switch off active track and initiate the rth using the rc
2017-12-20
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Kloo Gee
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Thanks for posting your FlightRecord for us all to try to parse and learn from.  Unfortunately for me, they raise more questions than answers.  The first one is that I find it very odd that the Flight Time in the video you recorded was only 4:11 and the actual FlightRecord has 4:45.  As you noted, none of the time stamps match up between the video and the FlightRecord log itself.  That is a first for me, but it could be that I just haven't looked that closely before.  Not sure.

Also, I find this FlightRecord to be interesting because this is the first one I've looked at in depth where ActiveTrack was being used.  In looking through the log, it is interesting to see the changes in pitch and movement throughout the log that don't have corresponding inputs from the pilot.  So for me, it is hard to decipher what exactly the active track was attempting to do.  To me though it is clear that there is at least a stiff breeze that is causing the aircraft to pitch and roll to try to compensate for it.  But it isn't clear to me whether it was hard enough to actually knock it off course at a couple of different points (including the final movements) or if that was just due to some "interesting" ActiveTrack behaviors.

In the end, I think the final death blow was that line of site between the RC and the AC was very likely interrupted.  You can see in the final moments, it lost connection for 4 seconds, followed shortly by a 1 second loss of connection, followed immediately by total loss of the signal (i.e. end of the log).  I think it is around the 3:50 Flight Time mark in the video (YouTube video mark 1:55) where the pilot understands they are about to lose visual of the aircraft and decide to try to gain elevation by moving the right stick up.  This can be seen in the FlightRecord logs at around the 4:24 mark where you can see the RcElevator value change from its default (1024) to a slightly larger value for a short time and eventually to 100% stick up (1684) about 8 seconds later.  Unfortunately for the pilot, I think that since the aircraft was in ActiveTrack mode, it did not obey the request to gain altitude and maintained its ~160ft height.

Because the aircraft didn't gain any elevation, the RC and AC lost direct line of site and a short time later started having connection problems.  At that point, it is hard for me to have a conclusion as to what happened because there isn't anything logged.  It SHOULD have initiated an RTH after a 3 second loss of connection and headed for home.

The direction it was headed at the time of the final loss of connection, it seems like it may have been very near the same elevation as the top of that large black building.  My guess is it either crashed into the top of it or just barely cleared it and continued on in the same direction past that building.  If you were lucky enough for it to have cleared the building, I don't suppose you went back and checked the original home point on the off chance it may have done an RTH eventually.  It had 64% battery left, so if it didn't crash right away, it eventually could have got its wits about it eventually and went home.  

Having said all the above, there was a pretty stiff wind that day that appears to be out of the SW that coincidentally or not appears to be in the same direction of the final leg of the journey as the signal was lost.  Again, it is hard for me to conclude if that is the wind causing that or ActiveTrack doing something "interesting".

Not sure I'm all that helpful, but it is an interesting case to look through.  I wish you the best of luck in a positive outcome!

Google Earth's perspective of the flight from roughly the spot the pilot was standing...
3.jpg

Google Earth's perspective of final leg vs. tall black building.  Not sure how accurate Google Earth's representation is.....
Did it hit it or just clear it?
1.jpg

2017-12-20
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