I've flown my fixed wing with APM:Plane firmware successfully for over 30 missions. Just earlier this week I experienced a crash that has rattled my confidence. I have some theories but hopefully you can help me reconstruct what happened by looking at some of the data. I feel like someone at NTSB trying to analyze data from a black box and have spent countless hours pouring over it. I've looked at numerous wiki posts on ardupilot.com, but have been unable to uncover the exact cause.
Right now my strongest theory is that a high voltage transmission line caused some sort of interference. You'll see below why I believe this is the cause, but hopefully someone can educate me based on the data from the telemetry log. Unfortunately I was unable to obtain the dataflash log.
This is actually a mission I've flown a few times before to help a friend get some aerial imagery of his property. Two weeks ago I flew this mission at 170m and he asked if I could fly a little lower. So I flew the exact same mission at 120m instead. The screen below shows the flight path in Google Earth. I drew in the white line to represent the transmission line. The flight path goes from left to right so you'll see that the line was flown over a couple times before the crash. The crash is on the right just south of the transmission line.
Now, check out the photo from my UAV right before the crash:
At the top of the image you'll see the transmission line and that the UAV is high above it. This image is taken heading from north to south. As seen in the Google Earth photo above, the UAV is heading north-south when it crashed in the field. Here are a couple more photos in the sequence where the crash begins. All photos are taken on a 3s interval:
You can see that it all happens right after passing over the transmission lines. I'm not sure if that's coincidental, but if I knew how to look for the right information in the logs it may be apparent that there's interference. I've gone through the steps below but nothing conclusive jumps out at me:
Finally, here is the tlog:
and the same log converted to text:
I'd greatly appreciate any insight that you may have to offer.