Aircraft disconnected and crashed

[rothe22]

I flew my P4P out a few miles to the local water tower and everything was going fine at first (I was getting a forward vision sensor error at the time, not sure if this is related). When I got to the water tower my HD video started getting choppy (I was on 5 gHz) but the controller signal was still 3 or 4 bars strong so i figured if i lost video I would just smash the RTH button and I'd be fine. While orbiting the water tower my aircraft suddenly disconnected and didnt reconnect. Dead, nothing, no signal, no GPS, no last known location. I hussled out there and sure enough, there was my drone, smashed to bits on the gravel. What happened? why didnt my drone RTH or auto land?

TLDR: I'm a noob and flew my drone out a few miles, aircraft disconnected, turned into a brick, you know the rest. what happened?

 

[msinger]

what happened?

Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.

 

[Just_nick]

Possible compass error, but the logs will be more telling.

 

[rothe22]

heres the .txt file. not sure how else I should upload this to you guys. the forum wont let me upload the .CSV or .KML file

 

[Fly Dawg]

If you follow the instructions that @msinger provided you can upload the data properly. If you did not follow his link try this one and place a link back here to that file once uploaded. Otherwise you will not get much help without the data file.

DJI Flight Log Viewer

 

[rothe22]

DJI Flight Log Viewer - PhantomHelp.com

 

[KongWerks]

Without seeing the flight log... Did the water tower block your signal? If you were moving in towards the water tower when the signal was blocked, it has enough time to fly into the tower and crash.

 

[Fly Dawg]

Initial look, compass errors approx 1min after takeoff. Flight should have been aborted at that point. Will look in greater detail when I have the time, but sure that others will chime in, in the interim........

 

[sar104]

From the Google Earth image of the water tower, taken on 3/10/15, the solar azimuth is 167°, meaning that the image was taken at 1135. That puts the solar elevation at almost exactly 45°. The tower shadow is 205 ft long, so the tower is clearly approximately 200 ft tall (205tan45 if that's not obvious).

The aircraft was at 236 ft above takeoff, which was at 930 ft MSL. The ground MSL at the tower is 1000 ft, so the aircraft was ~ 166 ft AGL, and so below the tower height.

It lost connection because the tower came between the aircraft and the controller. That will have triggered RTH. RTH height was set to 30 m (98 ft), which it was already above. If OA was enabled it should have detected the tower, stopped, and then climbed to avoid. Unfortunately the tower diameter increases with height, so it likely rose vertically until the props hit the tower.

 

[bsartist]

From the Google Earth image of the water tower, taken on 3/10/15, the solar azimuth is 167°, meaning that the image was taken at 1135. That puts the solar elevation at almost exactly 45°. The tower shadow is 205 ft long, so the tower is clearly approximately 200 ft tall (205tan45 if that's not obvious).

Or look up the sectional chart. ;-))

 

[sar104]

Or look up the sectional chart. ;-))

Where's the fun in that? But yes - it's there - 1216 ft, so ~ 216 ft high.

 

[rothe22]

I was well outside the diameter of the water tower so it didnt climb into it. I believe you are correct in your assumption that the water tower was between me and the aircraft. I watched the video on my controller from just before it cut out and it looks like i was flying about even with the water tower. Pretty good chance the drone smashed into it on RTH.

Shame on me for even attempting this. This was my first long distance flight and I did it with a P4P I bought on ebay that had taken a 10' fall. The left landing skid was slightly damaged when i received it and I ignored the compass error/controller announcing i was in ATTI mode.

is there a flight log on the internal memory of the drone I could recover? I'd like to see if it even tried to RTH or not.

 

[sar104]

 

[sar104]

I was well outside the diameter of the water tower so it didnt climb into it. I believe you are correct in your assumption that the water tower was between me and the aircraft. I watched the video on my controller from just before it cut out and it looks like i was flying about even with the water tower. Pretty good chance the drone smashed into it on RTH.

Shame on me for even attempting this. This was my first long distance flight and I did it with a P4P I bought on ebay that had taken a 10' fall. The left landing skid was slightly damaged when i received it and I ignored the compass error/controller announcing i was in ATTI mode.

is there a flight log on the internal memory of the drone I could recover? I'd like to see if it even tried to RTH or not.

It's clear from the track data that the aircraft was outside the diameter when it lost connection, but it will have moved towards the tower under RTH, stopped close to it, and then climbed to attempt to get past it.

The compass error was not significant and played no part in this.

 

[sar104]

is there a flight log on the internal memory of the drone I could recover? I'd like to see if it even tried to RTH or not.

Yes.

How to retrieve a V3 .DAT File from the AC

 

[bsartist]

View attachment 97492

What app is that you used for the chart?

 

[sar104]

What app is that you used for the chart?

ForeFlight.

 

[captainmilehigh]

ForeFlight.

Good choice. That’s what I use.....Foreflight/Jeppesen.

 

[rothe22]

It's clear from the track data that the aircraft was outside the diameter when it lost connection, but it will have moved towards the tower under RTH, stopped close to it, and then climbed to attempt to get past it.

The compass error was not significant and played no part in this.

not likely, I reviewed the footage from just before my controller disconnected and i was about even with the top of the water tower (the tower is perpendicular to the ground at the height i was flying). I'll see if I can post the last 10 seconds of the video.

I think its more likely that my forward vision sensors werent working and it slammed into the side of the water tower.

 

[sar104]

not likely, I reviewed the footage from just before my controller disconnected and i was about even with the top of the water tower (the tower is perpendicular to the ground at the height i was flying). I'll see if I can post the last 10 seconds of the video.

That would be interesting to see. I'm not sure how the altitude could be that far out though. The tower is listed as 216 ft tall and the aircraft was reporting 166 ft AGL - i.e. 50 ft below the top.