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Close Call/ Help Needed!

Discussion in 'Pro/Adv Discussion' started by scholls22, Feb 11, 2016.

  1. scholls22

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    have about 130 flights and never had an issue. Then yesterday happened. I was in the Smokey Mountains and wanted to get a few pics before I left. I updated to all of the latest firmwares and app updates last week. I went through all of the compass calibrations and did not have any issues during warm up. Once I got the green light I took off and let it hover for a few seconds to make sure everything was working properly. About 3 minutes into the flight, I lost signal and it started drifting away fast. I hit the RTH and eventually everything ended good for me.

    I uploaded everything to healthy drones to see if I could get an idea about what went wrong but I am not too familiar with what exactly I'd be looking for. Can anyone help me out with this?

    Thanks in advance! I don't want to put anyone or anything at risk flying until I know what went wrong!
     

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  2. alokbhargava

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    Please carry out analysis of the data but I would like to point out that I have been observing GPS loss on DJI Go app after release of 2.5.0. It looks P3 gets the GPS counts but Go App sees them differently. Not sure what's happening.

    You are able to use RTH clearly shows P3 had enough GPS in view to get your P3 back home.

    As you have 130 flights already to your record, we can't question you about the antenna orientation.

    Also, was your VPS off as we don't know it's behavior in dense fog/ smoke.
     
  3. scholls22

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    The antenna were properly positioned. VPS was on and there was not a lot of smoke/fog or anything where I was flying.
     
  4. Sinisalo

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    It looks like you have some major deviations in cell 1 of your battery, probably not related but just thought I would point it out. Also you were flying in some strong winds, 21mph average and 27mph gusts. Again, that wouldn't knock out GPS but would explain why you drifted once GPS Atti changed to Atti. I would contact DJI through chat or email and ask them what happened. Not sure you will get anywhere with that but you might.
     
  5. shockwave199

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    Define 'lost signal'. Lost all communication with the bird from the remote? Lost gps? What warnings if any were you getting? Maybe the strong winds just overtook the bird and you didn't actually lose anything in terms of signal or gps.
     
  6. flyNfrank

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    The gps is involved if he in deed was drifting. Otherwise it would hover in position based on it;s last command from the r/c.
     
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  7. scholls22

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    I got the Compass Error, Exit P-GPS mode when the issue took place
     
  8. eaglegoaltender

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    Doesn't sound like a wind issue if the RTH worked well and brought her home to you. GPS issue yes if your Phantom was drifting away quickly as you stated. However since RTH worked fine you must have had a decent signal to the bird from your RC. Kind of a head scratcher - was this your first flight in that particular area by chance?

    EDIT: Now that you mention "compass error", exit gps mode - There is another thread here that should help you out. Mid Air "Compass Error, Exit P-GPS Mode"
     
    #8 eaglegoaltender, Feb 11, 2016
    Last edited: Feb 11, 2016
  9. John Locke

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    Wouldn't a compass error switch it to ATTI, at which time the wind would take away in a drift?

    If there was a compass error as stated, how does the bird execute RTH accurately? I thought the compass had to work for the craft to know which way was home, even with good GPS signal.
     
  10. scholls22

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    Once, I got the error it switched to ATTI mode. I tried to control it and that is pretty much when the wind picked up a bit. From what I can remember, either it swapped or I swapped it back to P-Mode in hope of correcting it. That is when I didn't take any chances and hit the RTH. The first time I hit RTH, it did not seem to respond but a second time it worked.
     
  11. alokbhargava

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    "Why did you get a compass error" is remaining to be analyzed. All other sequences seem to be clear.

    If it is confirmed that you got an compass error, next step would be to check if compass is connected solidly.
     
  12. flyNfrank

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    If the compass is in error, he needs to look for a landing area before the aircraft finds one on it's own. Compass errors are to be taken seriously.
     
  13. scholls22

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    It was mid flight and I immediately landed. It was taken very seriously!
     
  14. TheRealNick

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    If you pull the .dat file we can see a lot more data. Use DJI go to put it in data mode and then use the usb cord to the phantom...not the gimbal, and when you plug it into computer you should see files that end in .dat. It makes one every time you turn it on, so may not be the right one. The file size is proportionate to the flight time. Post it on Dropbox and then we can take a look
     
  15. Meta4

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    Your flight record shows that the Phantom switched to atti mode at 2:57 and again at 3:10 and 3:34.
    This would account for the drifting you mentioned.
    If you saw a compass error at around that time, it strongly suggests that the Phantom had a problem reconciling the different data it was getting from the Compass and the GPS.
    The way the Phantom deals with this data discrepancy is to stop using the GPS data (it switches to atti).
    The most likely explanation is that you gave your compass a bad calibration in an area affected by the magnetic of some iron or steel like a car, structural steel or reinforced concrete.
    When you flew far enough away that your Phantom was no longer affected by the distorted magnetic field, the compass now reported a significant difference between the field it detected and the field where it was calibrated (compass error).
    Look closely at the area where you calibrated the compass.
     
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  16. John Locke

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    FYI, I had a compass error once for what seemed like for no reason at all. I was at the beach. I had flow two times within an hour prior with no compass errors. On the third flight from the same launch point I got a compass error 30 seconds into the flight, about 300' away over the same terrain I had flown two times before, flying over brush and dirt at 75' AGL. I didn't calibrate at this beach location, I calibrated in a school field right after loading 1.6 a week prior, at the same school field I always calibrate at, about 15mi away from this beach location. I had flown that calibration about 6 times before the beach flight, no problems. When the compass error happened I simply landed in ATTI and recalibrated the compass, then kept flying. It seemed totally random. I've never had this happened before in 140 flights. It surprised me. I'm still wondering about 1.6 firmware (given DJI's history of introducing flaws into what seems like EVERY firmware), but I haven't seen anyone else notice random compass errors after loading 1.6. Usually there's a reason for a compass error, but I haven't found mine yet. I'm going back there next week to fly the same place again, I'll see what happens.
     
  17. TheRealNick

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    If it was really windy it is possible there was no problem with the compass reading, it just didn't match the other sensors on the phantom....that is where the .dat file would tell us what really happened....same for your flight John if you think you still have it
     
  18. Meta4

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    Wind = compass error? I don't think so.
    If it worked like that we'd all be having compass errors all over the place.
    Besides the flight record indicates the wind was quite light.
     
  19. TheRealNick

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    More like gusting wind, something that makes the rotational rate of the z-axis gyro not match the change in yaw reported from the compass...

    That is where the .dat file may tell us what really happened...
     
  20. John Locke

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    Here's my report on Healthy Drones. The compass says it was fine, but you can see it changing to ATTI mode all by itself a bunch of times on the Notifications tab. The RC said Compass Error in RED. But the healthy drone report doesn't reflect that kind of error. Pretty strange. The other strange thing in the report is it implies I did an assisted take-off, stating that I was in assisted take-off mode. I never do that, in fact I have never done that. This report says that ATTI mode started from the beginning, however I know the RED error message didn't show up until I got out about 100' or so. It was GREEN SAFE TO FLY for at least the first 100' out from take-off point. I was flying FPV when I saw it go from GREEN to RED. I never took my eye off the screen from when I got 10' off the ground till it went into ATTI mode, at which time I turned around and immediately landed VLOS.
     
    #20 John Locke, Feb 12, 2016
    Last edited: Feb 12, 2016