How to analyze why P4P fell in flight

So I was mapping an area that I have done many many times but yesterday had some issues.

  1. I had to use my Android tablet because the ios ipad Pro would not run DD 4.17 (that has been fixed with 4.18)
  2. When using the Android tablet, the app would freeze if I left it open (active). But if I kept it “minimized” and simply popped it up every so often to check progress, etc, and then close it back, it was fine. I could check photo count, speed, etc.
  3. There were NO flight logs on the Android tablet for the flight that fell nor the previous 3-4 flights and no idea why not. The first 3 flights of the day had logs on the tablet.

For the fatal flight, I had already changed the battery once and continued the mission. The battery was getting close to 20% so at the end of a run, I maximized DD and clicked on RTH. I then looked up to verify the P4P was in fact doing the RTH and no uas. Looked back down to controller and had a red light / with message in DD regarding not being connected.

I had to keep moving and get other jobs done. I went back today and found the drone and pulled the flight log using Assistant 2 but there is nothing in AirData that gives even a hint.

Anybody here a guru on log files and can point me in the right direction?

You put the logs from the drone itself in AirData? Or out of the DJI folder on the Android? Can you share a link to the AirData upload?

Michael, there were no log files on the tablet so I pulled the log files from the drone itself using Assistant 2 and then uploaded that file to AirData. I did not know that AirData supported the log files on the drone until today. But I still can’t get any good details on what could have happened. I will send you a PM with full access to the Log file on Airdata. Thank you for looking at it!!

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I don’t see anything out of the ordinary, but unless there is a major malfunction AirData doesn’t show you much from the onboard DAT file. If there isn’t a txt file in DJI>dji.go.v4>FlightRecord then I don’t think there is much else to do. That is the main file with all the ins and outs per millisecond of what was happening. Especially if we are trying to scrutinize GPS and compass activity. Sorry for your loss.

Hi Tim,

Go have a read HERE to get a basic understanding of forensics on flight logs. Then, post your log on there and you will most likely get help to get to the bottom of it if indeed there is something to find.

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Thanks Dave! I opened that up and realize that requires a full cup of coffee and bright eyed status! :grinning: I will definitely give that a read. Someone suggested to me that it could very well be the power distribution board. Maybe I will get it figured out sooner or later. Thanks again for the link!

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Thanks for taking a look! I will read the link Dave sent but it seems that since there were no log files generated on the tablet, I may just chalk it up as part of the new normal of 2020 :slight_smile: Take care.

Haha… there won’t be an exam! :smile:
There are guys on there that enjoy digging into the forensics. Let them !

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I hear your pain. I had a very similar crash last early December while flying DD. I wasn’t able to find my drone (P4P) and therefore couldn’t determine why it suddenly dropped out of the sky. The highly damaged drone was found several months later by a farmer, but unfortunately (in many ways), the SD card disintegrated. It would have been nice to hear why your drone dropped. I would have attributed my experience to a battery failure, but the battery was recovered and still works fine today, go figure, even after a long Wisconsin winter.

Geo Tech, I originally suspected that somehow my battery came dislodged or just had cell failure. I had recently applied the Rain Suit to the P4P. But because of that I checked, double checked, and triple checked my battery when I snapped it in!! When I recovered the drone, the battery was fully snapped in and it had about 22% charge when it went down. I may never know what happened. If there was someone here on the forum who really knew how to do forensics, then I would send them the drone for inspection. Not knowing what caused it to drop, I will not put it back in the air.

That is interesting, Tim. Was the drone still powered on when you found it? If the battery was intact, installed, and still had 22% left, it would not typically power off by itself that I know of.

Dave, it was powered off but the battery was fully in tact. I used the same battery to power it back up and pull the log files off of it. So what I do not know is what the battery level was at when retrieved it. (I can not recall if the one green light was solid or blinking. It seems to me that there was a power failure of some sort and it dropped to the ground. This will likely be a case where I never know all of the details. But a good reminder that things can go terribly wrong. I don’t fly over people or moving vehicles and this is exactly why. Thanks for all of the replies.

One person suggested to me that it was a failure of the Power Distribution board. At this point it seems the most logical reason. The battery had enough power for me to leave it on for several hours while retrieving the logs. So it was not a case where it stayed on until the battery was at around 5% (or whatever level it auto powers off). The battery was fully intact so it was not battery separation. This would leave a failure on the distribution board as the most likely culprit. I will have to tear it down and see if there are any signs that corroborate this. I will put it on the shelf and look at it on a cold rainy day. But apparently the distribution board is the culprit for quite a few “Mid Air Drops”.

If it’s the board it must be intermittent if the craft Powers up now. That may be difficult to spot. Keep us updated if you can.