Battery Died - Drone Lost - Questions

[Youser]

Ok, finally got round to doing this after being reminded by another post about a similar incident.

DJI Flight Log Viewer - PhantomHelp.com

The Mavic travelled approximately 5,675ft after the end of the log. I see the strong interference warnings but I was still receiving video feedback and the rest of the data on the app.

 

[windwagen]

Hi, I lost my Spark last night and found this thread which has been somewhat helpful. I thought the battery died, and it may have. I used the Log Viewer tool and it only has 1 min 24 sec of data.

My question is....how precise is the Find My Drone coordinates?

I found some Lat/Long data in the DJI Record and shows that I started a video in the area close to where the Find My Drone app is indicating. That last video file is corrupted, unfortunately.

Oddly, the battery is 84% throughout the whole flight even though the voltage is fluctuating.

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[Meta4]

My question is....how precise is the Find My Drone coordinates?

It shows exactly where the drone was when it was last in contact.
But that's 440 ft up in the air, not where the drone crashed.

Oddly, the battery is 84% throughout the whole flight even though the voltage is fluctuating.

Your % indicator is only accurate when you fly with a fully charged battery.
Look at your cell voltages and it's clear that battery was partly discharged before the flight started.
By 1:16 the cells were down close to critically low voltage (3.3V) and pushing hard in Sport Mode only drained it more heavily.

 

[windwagen]

Thanks.... I'm trying to see if I can fix the corrupt video to see if there is more info. Next I'm thinking of borrowing a drone to search. The apparent landing area is quite open with a few trees so it shouldn't be this hard to find....

 

[windwagen]

No Go on that last video. What the Log Viewer doesn't show is that the DJI Record video data AND the find my drone locations are about 1000 ft SE of the Log Viewer... My intention was only flying straight up to take some videos. So I'm surprised that it flew 1000ft away. I don't recall touching the right stick at all. There wasn't any wind so a 440 ft vertical and 1000 ft horizontal seems unlikely.

Going to pick up that borrowed drone soon,

 

[Meta4]

No Go on that last video. What the Log Viewer doesn't show is that the DJI Record video data AND the find my drone locations are about 1000 ft SE of the Log Viewer... My intention was only flying straight up to take some videos. So I'm surprised that it flew 1000ft away. I don't recall touching the right stick at all. There wasn't any wind so a 440 ft vertical and 1000 ft horizontal seems unlikely.

You are correct that 1000 ft away sounds unlikely.
Drones don't just fly 1000 ft away by themselves, particularly when the battery is about to die.

 

[windwagen]

I had a look around the area with my buddy's drone. It's hard to see with my small phone display though. No luck...

Going back to the video that was sent to my phone, it looks like the drone was flying South. I panned it a few times and it appears to still be flying south rather than forward. ie pointing North, it was flying backward. Again, I don't recall using the right stick.

Is it possible for the drone to malfunction this way? I'm thinking that it may have lost contact only 1000 ft away, but it may have kept flying south for a few minutes? Is this even possible? To fly in the same direction while panning would require some real coordination. If this is true, I'm searching in the wrong area.

 

[Meta4]

I had a look around the area with my buddy's drone. It's hard to see with my small phone display though. No luck...

Going back to the video that was sent to my phone, it looks like the drone was flying South. I panned it a few times and it appears to still be flying south rather than forward. ie pointing North, it was flying backward. Again, I don't recall using the right stick.

Is it possible for the drone to malfunction this way? I'm thinking that it may have lost contact only 1000 ft away, but it may have kept flying south for a few minutes? Is this even possible? To fly in the same direction while panning would require some real coordination. If this is true, I'm searching in the wrong area.

This sounds rather complicated and it's hard to make sense of.
I'm puzzled at how you believe you have video from after the loss of signal?

If you lost the control signal, the drone won't keep flying or start to fly somewhere away from the home point on its own.
When signal is lost, the drone stops and shortly after commences to RTH.

 

[windwagen]

Puzzled - Me too.... This thing has been very reliable until now. I've flown it without charging ....flight time is short, but all the functions work. I recently re-read the manual and found something about the battery automatically discharging to 75% after 10 days. I would agree with that although I didn't know it was a built-in function.

Back to the confusing parts of the final flight...

1. The Find my drone position and the last entry of the Log Viewer are about 1000 ft apart. Please review the two attached pictures to compare. I know the Find My Drone says "11 hr missing duration. That was me with my buddy's phantom searching for the spark in the same area.

2. The log viewer is only 1:24 sec.... The Log Viewer shows a position that doesn't move from the launch and home position...like I intended. But the video here shows that it is moving. So the log viewer quit but video was still being transmitted.

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0-4s - It's moving to the right (South)
4-10s - It pans to point south and is flying forward...also south
10-15s - keep flying forward
15-18s - pan 180 deg...pointing north, but flying backward....again south.

3. I never intended to fly around - certainly not 1000 ft away. I just wanted to go straight up and take some video. To fly South and pan around while Still flying the same heading would require careful stick coordination....certainly I was not doing that!

4. My phone received 3 videos from that flight. The 1st and 3rd are corrupted. The size of the 1st and second (posted in the youtube link) are about the same. The last one is about 1/0 the size so maybe 3 sec. From the landmarks in the video, I would agree with the find my drone position. The real question is whether it fell out of the sky there or did it keep flying for a few more minutes....which would be practically impossible to find.

I'll see if I can have something done about that last video. Any other suggestions?

 

[sar104]

The txt log is basically worthless here. If you can retrieve and post the mobile device DAT file (FLY126.DAT) it may contain raw GPS data that are missing from the txt log.

How to retrieve a mobile device DAT file: How to retrieve a V3.DAT from the tablet

 

[windwagen]

Here it is.I found another Log Viewer text file... It's more recent than the last one. Not sure how I missed this.

What's really interesting is that the drone in descending and moving...but look at the sticks...esp the right one. It's neutral but it's moving South East and panning (not south like I thought) I would say this log matches the video I posted earlier. and the lhe location where this log ends is moving towards the location where the last (corrupted) video started. So the crumb trail DOES lead towards the find my drone location.

DJI Flight Log Viewer | Phantom Help

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I hope the attached .DAT works - thanks!

 

[Meta4]

Here it is.I found another Log Viewer text file... It's more recent than the last one.

In the second flight data file you pull the left stick down from 2:09.1 to bring the drone down.
Shortly after at 2:14.2 you get error messages warning of Yaw Errors and the Mavic drops out of GPS into Atti Mode which allows it to drift with the breeze.
You stop descending at 2:27.6, leaving the drone at 266 ft high and now 200 ft away from home.
At 2:40.9 you recommence descending ... now over 500 ft from home.
The data stops at 2:46.1 with the drone still 236 feet up, 630 feet from home and still drifting further.

 

[windwagen]

The Yaw error is disturbing. I found some posts about that and similar stories. Atti mode makes sense although I've never experienced a flight like this. What can be done with the .dat file?

 

[sar104]

The Yaw error is disturbing. I found some posts about that and similar stories. Atti mode makes sense although I've never experienced a flight like this. What can be done with the .dat file?

It dropped into ATTI at 165 seconds because the NavHealth went to zero. The cause was sensor fusion failure:

164.234 : 7972 [L-FDI]ns req:fdi,0to0,reason:fusion.gps_yaw_err,result:fail for same index​

164.278 : 7974 [L-FMU/LED]action changed. imu error:ns_abnormal(3)​

165.418 : 8031 [L-FLYMODE][Ctrl<1>] REQ_RC_NORMAL ATTI ctrl_atti​

The problem was not GPS reception - that was fine:



There was no significant yaw error:



However, looking at the 3-D velocity data, the discrepancy that arose between the IMU and the GNSS data is obvious:



The DAT files you posted were split, presumably because the app restarted. Looking at the combined pure GNSS data shows the progress of the flight until the disconnect:



Importing those data into Google Earth gives the following flight track:

 

[windwagen]

So if I understand correctly, I should look somewhere between the red and green lines...or a bit to the right (south) of where it ends. We can't tell the true battery condition can we? So it may not have crashed in that area?

I can tell you that I did unplug my phone and rebooted it a few minutes after it "lost contact". I can't say for sure if this is after 215 sec....

 

[sar104]

So if I understand correctly, I should look somewhere between the red and green lines...or a bit to the right (south) of where it ends. We can't tell the true battery condition can we? So it may not have crashed in that area?

I can tell you that I did unplug my phone and rebooted it a few minutes after it "lost contact". I can't say for sure if this is after 215 sec....

Sorry - I mistakenly thought that you had found it already. No - it's not going to be anywhere near there, but I can extrapolate based on the battery level and drift speed to give you an estimated landing area. Stand by.

 

[Stoney B]

What ins co? I'm a new owner, mp came the other day so not flown yet till i get coverage along with dji refresh. I have state farm and & secy said he's out of the office & she didn't know. Thanks

 

[sar104]

Here are the drift calculations:



If we assume an approximately constant wind direction and speed, that should have put it on the ground 835 m downwind of the last recorded location, somewhere in the vicinity of the yellow pin:

 

[Mossiback]

I had a look around the area with my buddy's drone. It's hard to see with my small phone display though. No luck...

Next time record video of the search and review on a large screen.

 

[windwagen]

Thanks.... Oh man....that's crazy. I'll check that area in the morning.

What plot tool is that? Can I download it? It looks like one I use for some industrial equipment which I tried. It would accept the .dat file but the results are jibberish.

Yeah - I didn't insert a memory card...cuz it's still in the lost Spark!!!! j/k...