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P3A Midflight disconnect - drone did not RTH

Discussion in 'General Discussion' started by Tyler navarro, May 8, 2016.

  1. Tyler navarro

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    Today I was flying at a beach on the south side of kauai. After about 5 minutes of flight about 200 yrds offshore. I was standing approx 15 yrds inshore. Approximately 2000 ft away, while trying to bring drone back to me, experienced sudden, unexpected disconnect. There was no gradual weakening of signal, as experienced with other situations I've been in where obstructions get in the way. Just Sudden, unexpected disconnect. Even though I had LOS, could not reconnect and aircraft did not RTH either after disconnect or low battery. Based on recollection, I was approx 200 agl. I have approx 18 hrs flight time with p3s and P3A, fly in p-gps mode all the time. Home point was properly set to correct location based on dji go app.

    End story, total airframe loss with no idea of where the drone ended up or what caused disconnect. I have attached flight log, could someone who has more experience reading that file take a look at it and tell me if there's anything in there indicating cause of sudden signal loss? I was taking video at the time, but video is not viewable because file didnt end record properly. I can upload video if that will help.

    P3A
    Note 4
    No mods to aircraft or controller
     

    Attached Files:

  2. With The Birds

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    Battery looked ok, a couple of deviations at startup then clear. Plenty of juice left when signal lost.

    I notice you had 25mph winds 500 feet out at 85ft reported altitude. You got over 400ft up further out. It might be rth initiated and the wind prevented return before battery exhausted. The logs dont reveal anything helpful i am afraid.
     
  3. Tyler navarro

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    Does the flight log indicate where RTH was set?
     
  4. Tyler navarro

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    @With The Birds. Yes I believe I strayed over 400ft momentarily. I have my max altitude set to max because a couple says before I was trying to shoot over a mountain pass. The us law is 400ft agl, not 400ft from point of launch. During my flight I noticed I went over, but after that kept the altitude well below the 400
     
  5. Meta4

    Meta4 Moderator
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    There are some odd screwy things in the flight record.
    Although the battery is showing 98%, the flight record starts at 13:41. ??
    There's something screwy with your altitude data, it's showing as 2700 feet at the start.
    At 13:48 this seems to settle down and it now shows a more believeable 85 ft.
    At 14:05 the timestamp resets to 0:29 which puts the time about right.
    You are getting frequent lost downlink messages that all last for 3.3 secs.

    At 3:19 there's a glitch in the speed data that made the Phantom think it is moving at 500+mph for one second.
    The recorded altitude had been steadily descending from 440 ft at 0:36 until 3:40.
    Is this accurate or were you in level flight all that time but with screwy data?

    At 3:40 your altitude data jumps from 94 ft to 2770 ft, but at 3:49 it comes back to 94 ft..
    The flight data ends at 6:07 with no unusual indications and 72% battery.
    There is no indication that RTH ever initiated and no indication that the Phantom ever lost connection, just short downlink drop outs..
     
  6. Tyler navarro

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    @meta
    Is that weird flight data in the beginning normal? Have others seen it/is it a known glitch or something worse.
    I immediately climbed during the flight up to that ~440 and was descending after that. Bht that 94 ft at 3:40 seems weird, as I was well above 150 feet (in know because I have taken video of the same spot at 60 ft and was thinking I should get lower to duplicate the shot.

    As for the end of the log, so there's nothing in there about a gradual loss of signal? What I saw was going from full signal to total dropout. I was sitting down and so i hadn't suddenly walked behind an obstacle, and I was starting to retrace my flight path more or less as I knew I would signal coming back home.

    I've been looking around on the forums, but can't seem to find a similar situation. Unlike most others, I have not been suffering disconnects in other flights (which indicate firmware or compatibility issue). The closest thing I would call it is a flyaway, but that issue seem mostly fixed in the p3 series compared to earlier Gen. I've seen in other comments that dji has given discounts for failure somewhere along the line. I want to buy a new aircraft but Am wary of spending full price and suffer this mystery issue again. Have you seen a similar situation with disconnect and RTH fail?
     
  7. Meta4

    Meta4 Moderator
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    I haven't seen any flight records before where the data jumped around like yours did.
    It's hard to know if the sensors are actually reading wrong or something is scrambling the data recording.
    The way the time was also shuffled, makes me suspect it could be a data recording error perhaps?

    The repeated dropped downlink for 3 seconds is another thing I haven't seen before
     
  8. Tyler navarro

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    @meta

    Thank you for your help, I'm going to try and get some technical information from DJI and see if their tech support can help. Hopefully, it will get seen by an electrical engineer and not just a phone depot person