Loss of control, frequent 'emergency' landing

On a maiden flight on a new build it seems to fly fine for moments. It then starts drifting a little to much in seemingly random directions, though in a slow progression. And then just lands gently, as if triggered by some sort of failsafe.

Log is attached. I see a lot of vibe failsafe errors, yet the vibe values look good (usually <10), maybe spike on landings. I also see a lot of EKF PRIMARY errors. The POS drawn on the map looks very erratic and way outside where I actually flew, yet the GPS drawn on the map looks reasonable and smooth.

(Fixed) Log link: https://paste.c-net.org/OnionLaughter

A tlog is of limited value. Link to the .bin log file.

screenshot for convenience, @dkemxr sorry, will upload bin file

sorry about that, fixed the log link.

A vibration FS will be triggered when 3 conditions are met and that will trigger Vibration Compensation the result of which you are seeing. Drifting and slow response to command. The conditions have to do with the position estimate. You can read the Wiki and plot these parameters. In your case it’s the vertical position estimate; it’s way out. Not sure what to make of theis baro graph. You can see where it touches the ground initially from Z-vibe (not plotted) but then what happens?

All of the bumps in altitude are from separate takeoff events, from approximately the same altitude. looks like a biased drift downward in the height measurement / sensor, when it should be fairly level. not sure if the 6m drift seen over the course of a few minutes or less is significant; it seems so.

wonder if the batteries were affected by the freezing weather…

There are several Pre-arm-need altitude estimate or EKF altitude is bad messages present. Which jives with poor vertical position estimate. Regarding the cold weather the baro temp tracks the slope of indicated altitude. So I suppose you should let the temp stabilize before flying.

nice, thanks. i did not anticipate sensor temp would be a problem.

I left my copter outside for a while before flying and I did not encounter this problem.