Strange crash during mapping mission.. help with log analysis!

Quadplane running Arduplane 4.3.3 on Cube Orange. Target airspeed was set to 19m/s.

There may have been ice buildup but the crash was so hard (30+m/s to trees) that any evidence of severe ice buildup was lost.

This is strange one, i have no idea what happened:

Autopilot log file

It just went full forward motor throttle but didn´t even try to pitch up to clear the hill, why?

Are you sure that the linked log file is the right one ? I can’t recognise the curve of your graph there.


Zoom in here

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Now I see what you mean.

Apparently the waypoints have different target heights. According to the TECS data (TECS.h , TECS.hdem) the target altitude matches the actual altitude all the way to the impact ! It is interesting that the TECS altitude always followed the mission command altitude, only suddenly it did not at the last waypoints before the impact. The reference altitude of the waypoints has not been changed, so the answer as to how this can happen is unfortunately beyond my horizon. I am also curious how this can happen.


Yeah, this is how we have been doing terrain following. We generate waypoint file with our own custom software and each waypoint has target altitude that is referenced to home altitude. Has been working just fine for years.