Hi all - I'm hoping some experienced eyes can help me diagnose the root cause of unscripted spiral flying that eventually led to a crash while on a simple mission in auto flight mode.
This is the 4th mission this quad has flown, and the ~25th flight. Every other mission and flight has been perfect, and stabilize, RTL, land, alt hold, loiter, and circle modes successfully exercised. This particular mission had more steps than the others, but it was still quite simple: takeoff, down and back along ~150m course 3 times, RTL, and land, with some condition_yaw changes at the waypoints for different on-board GoPro shots. On the 2nd trip back along the course, the copter started aggressively spiraling in ~30m circles. I finally got it in to stabilize mode but made an orientation mistake and ended up crashing it into a low fluffy pine tree trying to get my bearings. Luckily the copter suffered no damage and performed wonderfully on some short stabilize mode test flights afterwards. In fact the MP and TX telemetry never lost their connection to the copter. That's great, but I obviously don't want to attempt further autonomuos flights until I understand what went wrong.
From what I have read on other posts and on ArduPilot.com this behavior during an auto-mode flight is indicative of a GPS failure. So I analyzed the tlogs and flash logs according to the Wiki and found nothing out of the ordinary. Number of sats is always 11 and the hdop never appears to climb above 1.3. When I planned the mission I changed the waypoint radius from 30m to 5m could that be a cause?(Why does it default to 30m in the first place?) Anything else I'm missing?
Tlogs and flash logs are attached, and I'm using a standard 3DR quad build, MP v1.2.70, APM firmware v3.01. The logs have a long dead space at the end where I was figuring out how to get the copter out of the tree.
Many thanks in advance, Henry