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CRASH: P3Pro fell out of sky while in follow me mode.

Discussion in 'Pro/Adv Discussion' started by mgerety, Nov 17, 2015.

  1. mgerety

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    Scenario: Had P3Pro in follow me mode at ~47m. Did pre-flight check list, etc. Compass good. Home point good. Tested RTH from same spot a few hours earlier, drone successfully RTH'd.

    Had eyes on Drone's LEDs through moonroof of car it was following (was night time), and could clearly see car taillights on iPhone 6 plus using DJI go app. Pulled over to find a landing spot for the drone to put it in the car and bring it across town.

    DJI Go app stated bad connection, connection recovered, then "No connection".
    Walked up and down street past last good GPS point, never regained connection with drone. Never touched sticks. Drone did not Hover or RTH.

    HealthyDrones link for flight: HealthyDrones.com - Innovative flight data analysis that matters

    Note: on the map, the industrial area you see where the connection gets bad is a greenhouse called Casertanos in Cheshire, CT. I'm not posting a link because my account got cancelled for SPAM last time I did, but you can look it up in google.

    The drone was set to RTH on lost connection. Looks like right before it crashed it switched to ATTI mode and went down. I DID NOT touch the controls prior to this happening.

    As far as I understand it, even if I completely lost connection , the drone should have RTH'd or hovered. It did neither, just went down.

    There are no towers, flagpoles, or tall structures (other than trees) in the flight path. None of them are near 47M high.

    Any ideas? Feedback? Something I'm missing?

    Thanks.
     
  2. msinger

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    It depends what you have set in the DJI GO app. In the "Advanced Settings" section, the "Failsafe Mode" setting can be set to "Return-to-Home", "Landing", or "Hover". If set to landing, it would do exactly as you described.
     
  3. mgerety

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    Right. I had it set to RTH. It was absolutely NOT set for Landing, I have triple-checked that.
    It did not land, it fell... HARD. Bent one of the arms and broke 2 propellers. Thank god it landed arm first, as the camera and gimbal are OK.
     
  4. msinger

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    It would also have landed at it's current location if the home point was not marked or your Phantom was connected to less than 6 satellites (not likely).

    The Healthy Drones map shows the last location was above a bunch of trees. What are the odds that it clipped a tree and crashed to the ground? It seems pretty likely.
     
  5. flyNfrank

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    Zip and attach a copy of the .txt file from this flight to a post in this thread. The file is in the mobile device used for this flight. With the .txt file some of us can provide much better details as to what may have taken place.
     
  6. mgerety

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    The height was 47M. I recovered it from the woods, and there's no chance those trees were taller than 30-40 feet at most. The final resting altitude did say -17M.. So even if we adjust for some altitude change, and put it at 30M, that's still 98.43 feet. The trees are just not that tall.

    Maybe there was some kind of bad altitude reading or something..I don't know.. maybe the reading was wrong -- it's weird that before the crash vector on the map it switched into Atti mode. Maybe that was some indication of some kind of error... unsure.

    Idea being, I'm trying to figure out this was a drone malfunction/issue or operator error. Based on the readings / previous successful operation / history, I don't see what I had done incorrectly, but maybe I did.
     
  7. mgerety

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    I've uploaded the requested .txt file.
     

    Attached Files:

  8. msinger

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    So, it most likely either hit a branch of it descending into a tree when the signal was lost. As flyNfrank mentioned above, we will only be able to help if you post your entire flight log. Your Healthy Drones link above does not reveal much.
     
  9. msinger

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    It looks like the remote controller lost the signal when your Phantom was at 286 feet. It descending slowly from that location, hit something (a tree probably), and crashed to the ground.
     
  10. Jbundy63

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    Could be wrong but is there a chance that there's an terrain change in elevation,such as ground gaining some height as you fly in that direction? Obstacles being higher that at the original home point. When I fly distance I usually stay around the 400 foot mark
     
    #10 Jbundy63, Nov 17, 2015
    Last edited: Nov 17, 2015
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  11. msinger

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    Check out the log above. That doesn't seem to be the case.
     
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  12. Jbundy63

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    Yeah I just seen that after I posted, That seems to be what happened.
     
  13. mgerety

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    A crash into a tree would be the simplest explanation, for sure.

    If that's it, that's perfectly fine. What I'm trying to figure out is HOW?! The tallest tree in New England is 179.2 feet tall. It's a white mine in massachusetts. The trees this was near were 50 foot (max) oak trees.

    I want this to be a learning experience. Could it have been altimeter sensor failure? How could I strike something when the drone by all accounts was at lowest 98.43 feet, and there is nothing near that height in the area. How can I prevent future collisions? Flying a minimum 50 feet above all obstacles seems like a pretty safe bet.
     
  14. TC Malker

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    It struck a bird.
     
  15. mgerety

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    It was night. Maybe a bat?
     
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  16. mgerety

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    Also, what's up with the switch to Atti mode? -- any idea?
     
  17. bbfpv

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    I haven't dug into the actual log file, but just based on your flight path, there is a 128ft change in elevation from your HP to your CP.
    upload_2015-11-17_14-43-19.png
     
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  18. mgerety

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    Now THAT might explain it. Is the elevation measured by the app/drone based on the launch point and not relative to current position?
     
  19. bbfpv

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    Yes.... the height of the drone as measured by the drone is always relative to the height of your launch point...
     
  20. mgerety

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    ok.. that is likely it then. Thanks a ton for helping me understand what might have happened.