Help with accident reconstruction

Much thanks to Cambridge PD, I did in fact recover the drone. I got in touch with a detective from the CPD after calling into the cambridge police a few times to ask if anyone had returned it. The Detective (and the lady that reported it) both went way over and above to return the drone. Apparently an older lady found it in her backyard, and called it into cambridge police after doing some research and learning that it wasn't just a toy from her neighbors kids. So much thanks to everyone involved!

Whats crazy is how far the drone landed from where I had searched for it. I wrote up the details of my search in a separate post (viewtopic.php?f=27&t=32474). The drone was actually found more than 2000 feet away from its take off point, and 1300 feet away from its last reported position. I had been searching in entirely the wrong neighborhood since I had assumed the drone was no more than 500 feet from launch.

According to the video, the drone went on very long (although strangely controlled) journey after loosing contact, traveling nearly 2 miles, and made two separate self-controlled attempts to return to base. During the next 7 minutes of flights after loosing contact, it traveled nearly 4000+ feet away from takeoff, crossing a town line into Davis Square! I still have no idea how this could have happened. (FYI you can see a lengthy writeup after I lost the drone (but before I located it) is here (viewtopic.php?f=27&t=32474)..)

The video shows a crazy path, although the drone maintains altitude around 300 feet the entire time and at no point "drops out of the sky". For reference, at t=0:00 I had set the home position in the center of a 58 acre field. The drone takes off and starts panning around the park as intended. Everything is going great, although the drone is traveling a little further than I intended. At 3:45, at 300+ feet high, it starts spinning wildly and reports its last location back to me. At that point the display on my device has frozen and shortly after I switch the transceiver off to trigger automatic "return to home". I can no longer see the drone. You can see me in the distance running forward trying to re-establish contact. Then suddenly the drone stabilizes at 3:48, and hovers perfectly still until 3:55. Inexplicably, the now-uncontrolled drone starts picking up speed to the NE at a heading of 60 degrees, which is sort of an odd direction away from the home position. The motion looks smooth (probably the gimble??) but the drone is moving far faster than it normally would in controlled flight. At 4:46, it seems to stop, having moved about 1600 feet in under a minute. Maybe a massive burst of wind..? Then much more slowly it starts moving back to the home position, I suppose fighting to return back to base. Never the less, the drone is moving now slowly directly back to the field. Then around 5:21 its only a third of the way back to the home position and disaster strikes again. The drone starts moving NE again quickly -- easily more than 30-40 miles per hour. It crosses Mass Ave 2A at 6:23, and by 6:58 it reaches Davis Square, Somerville, the next town over. This is more than 4000 feet away from launch. By 7:00 the drone is practically over the David subway station and then seems to take a powered turn (you can see the rotors tilting) and and starts making a controlled flight towards the home position for a second time. Ironically I'm already packing up my gear because I assume the drone has crashed, but the drone is still aloft, well over 300 feet high and working its way back to home. The trip back home again seems much slower but the drone appears to be making course corrections. After 2 minutes of slow, methodical movement back towards the home position, the drone is about halfway back home, at a distance of 2060 feet from home position. Just past 9:05 it apparently decides it can't make it back to base with remaining battery and attempts an auto-pilot controlled landing. At 9:13 you can see it slowly, methodically descending straight down in emergency land mode. At 10:17 its is now at the tree line, and gets tangled up in the branches of a house with lots of solar panels. It crashes to the ground, then bounces(!??) back into the air about 20 feet and then lands in a fence. At 16:24 the video cuts out.
 
Amazing story and congratulations on recovering your Phantom! I had my doubts that the poster was really the police. How interesting that they found their way here, created a profile and posted in the right thread to let you know they had it. Simply amazing as is the actual flight it took. Hats off to the police department! Get yourself a Dymo label maker and put some info on that bird! I have mine covered with contact info just in case. ;)

PS - wheres the video?

PSS - maybe you should approach your local TV stations with a recognition/thank you story about the great lengths the police went to help you out. C'mon, theres a drone involved I bet they would suck it right up!
 
Sounds like it was losing and acquiring 6 sats multiple times and switching from GPS to ATT to GPS... etc. It's possible every time it acquired sats it tried to Return To Home, but then would lose sats and get knocked down to ATT mode and either fly in the wrong direction or drift with some wind gusts. Had you noticed sat count during the time you still had telemetry? Was it fluctuating? Amazing story. Nice police department. You should offer to train them on flying a drone if they are ever interested. All police departments will eventually have one in their arsenal.
 
Video is here. Please be kind. :) https://www.youtube.com/edit?o=U&video_id=fNSxHqYfIYw

Yes, Cambridge PD was awesome.

I like the loosing sats/ gaining sats theory since it sort of explains the back and forth behavior. I don't recall how many sats were reported at the time but following advice from others I never take off unless there are at least 7 sats. I'll have to watch the sat count more carefully -- by the time I took a screenshot the connection had already been lost. My general experience is that once the drone has cleared the ground it usually has no problem reaching 8+ sats. Does return to home not work if it falls below 7? That seems odd given that you can triangulate a position usually with only 5 or 6.
 
it looks like after your "flip and bounce" the phantom rose up into some overhead wires, which then
sent it back down!
glad you got it back! great to see the video, at least you have a record for DJI in case they
want to investigate.
what damage was there to your phantom?
it looked like the motors were trying to spin until the video ended..............
 
If it drops below 6 sats it will drop out of GPS and into ATT -- where it has no idea how to get home. Unfortunately, the Phantom needs 6 sats at a minimum to "triangulate". I can't explain that wild yawing it did at that one point. Thought maybe you accidentally had hit the rc S1 switch into Manual Mode, maybe having never changed the NAZA S1 to Failsafe -- but I assume you made that change. So I'm leaning toward a loose GPS cable plug connection that was discussed in a past thread, giving you intermittent GPS sats.
 
jgilbert20 said:
Video is here. Please be kind. :) https://www.youtube.com/edit?o=U&video_id=fNSxHqYfIYw

Yes, Cambridge PD was awesome.

I like the loosing sats/ gaining sats theory since it sort of explains the back and forth behavior. I don't recall how many sats were reported at the time but following advice from others I never take off unless there are at least 7 sats. I'll have to watch the sat count more carefully -- by the time I took a screenshot the connection had already been lost. My general experience is that once the drone has cleared the ground it usually has no problem reaching 8+ sats. Does return to home not work if it falls below 7? That seems odd given that you can triangulate a position usually with only 5 or 6.
cpd said:
Still waiting contact from person who posted losing the phantom in Cambridge. If anyone has additional contact info for him/her requesting your assistance. Formal methods take substanially longer and just trying to save him from purchasing another phantom.

CPD, you rock. Brilliant story with a great ending. Virtual first-bump from over in the UK to you ;-)
 
Wow I have read and seen many fly away videos and this is downright amazing
Glad to hear you recovered it

I suggest a gps tracker as you have already found out what happens if the data link fails

At least the pd came through and returned it to you
 
jgilbert20 said:
Video is here. Please be kind. :) https://www.youtube.com/edit?o=U&video_id=fNSxHqYfIYw

Yes, Cambridge PD was awesome.

I like the loosing sats/ gaining sats theory since it sort of explains the back and forth behavior. I don't recall how many sats were reported at the time but following advice from others I never take off unless there are at least 7 sats. I'll have to watch the sat count more carefully -- by the time I took a screenshot the connection had already been lost. My general experience is that once the drone has cleared the ground it usually has no problem reaching 8+ sats. Does return to home not work if it falls below 7? That seems odd given that you can triangulate a position usually with only 5 or 6.
Great story,, I tried the link to the video but it says no video found????
 
this sucks,, i'v been waiting days to see how this story panned out and now i get no video
 
jgilbert20 said:
Video is here. Please be kind. :) https://www.youtube.com/edit?o=U&video_id=fNSxHqYfIYw

Yes, Cambridge PD was awesome.

I like the loosing sats/ gaining sats theory since it sort of explains the back and forth behavior. I don't recall how many sats were reported at the time but following advice from others I never take off unless there are at least 7 sats. I'll have to watch the sat count more carefully -- by the time I took a screenshot the connection had already been lost. My general experience is that once the drone has cleared the ground it usually has no problem reaching 8+ sats. Does return to home not work if it falls below 7? That seems odd given that you can triangulate a position usually with only 5 or 6.
Great you got it back, thanks for sharing the video.
 
Glad to hear the good news. Glad there is a good story about the police. Seems like they went out of their way to get it back to you.
 
As has been stated, "Never fly your quad without a tracker." You may not be so lucky next time.
Good you got it back.
.
After watching the video, it looked like you took off and moved around the field. I could not see any check once in the air if you actually had a home lock. IMHO it is always a good idea to get up in the air and confirm the quad will come back to you. I do not trust the colored lights because I don't see them that well.
 
Video link don't work for me :( I want to watch the outcome
 
general01 said:
Video link don't work for me :( I want to watch the outcome
Try "dutch" link on page 2. Worked for me.
 
Happyflyer said:
I could not see any check once in the air if you actually had a home lock.

I think the craft did appear to have a home point due to it's behavior in attempting to return to the takeoff location a couple of times. The OP should open it up and check for a loose GPS connection at the very least. I think we'd all like to know if it was loose because that would backup FlynFrank's flyway theory.
 
MapMaker53 said:
Sounds like it was losing and acquiring 6 sats multiple times and switching from GPS to ATT to GPS... etc. It's possible every time it acquired sats it tried to Return To Home, but then would lose sats and get knocked down to ATT mode and either fly in the wrong direction or drift with some wind gusts. Had you noticed sat count during the time you still had telemetry? Was it fluctuating? Amazing story. Nice police department. You should offer to train them on flying a drone if they are ever interested. All police departments will eventually have one in their arsenal.

Good call MM, absolutely what happened....you are a lucky guy jgilbert!
 

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