Take off in qstabilize mode, and then switch to FBWA mode. The aircraft will quickly reduce the altitude until it crashes
NOTE: I haven’t reviewed your log file.
You must switch to and enter QHOVER mode before switching to FBWA mode. Remember that during a transition, the airplane starts to fly on the wing, while “holding” the last known quad mode state command. There is no altitude hold in QStabilize, so an immediate change to FBWA means you may likely lose altitude.
Also check your transition parameters. If you do not hit the defined airspeed for the specified amount of time, the transition will not be complete and I’m uncertain what the airplane does. It may just keep flying in last commanded Qstabilize - losing altitude until impact. Your airspeed and/or time interval may be set too high.
The proper sequence for an altitude hold transition is QStabilize > QHOVER > FBWA.
Thank you for your reply.
I use QHOVER > FBWA，which is very effective.