While flying inside with a quadrotor with an HKPilot32 running ArduCopter V3.6-dev (why a dev version was used is another discussion...) and equipped with a LIDAR-Lite 3 and a disabled GPS, the quadrotor hit the roof (battery disconnected at that time) when we activated the auto land mode.
From the DataFlash logs, we see that CTUN.DAlt (Controller TUNing Desired Altitude) was set to around 4.6 m at that time (which is consistent with the quadrotor sudden ascension), while the quadrotor was flying around 1-2 m of altitude when land mode was activated. We see also that a previous land succeeded 2 min before, so the problem was quite unexpected.
Although the Auto Analysis function on our log suggests that we had accelerometers accuracy problems, I do not understand why CTUN.DAlt got this value considering the current altitude estimation. How is the desired altitude chosen in land mode? Also, is CTUN.Alt the best altitude estimation used by the land controller, or is it another one (I looked also to XKF1.PD but it is quite similar, but with the opposite sign)?
Thank you for letting me know if you have explanations on this behavior (log is in attachement)!