Failsafe&Crash - Failsafe reason from logs?

Hi, I’ve crashed my Skywalker plane last weekend when I was testing it with APM 2.5 with APM:Plane 3.3 FW.
I had two flights. First one was quite long and it was OK, but the second one finished by crash very shortly after take-off as it’s possible to see when telemetry log is replayed in Mission Planner (please rewind to 80% of it). Actually, few seconds after take-off I’ve completely lost control over plane - it autonomously decreased throttle, rolled left and consequently hit the ground and crashed.

I can see from logs, that the reason was FAILSAFE trigger that put plane to CIRCLE mode when it was about 3 meters above surface, but I have no idea what was the reason for this event.

Can anybody please take a look at attached dataflash and telemetry logs and parameters file and explain me what was the issue? Thank you…

I’ve just noticed that dataflash log is missing IMU values, which is a bit strange (log from first one flight contains those values) - maybe it’s connected with reason, maybe not

you lost RC , - the signals are not gone, but just flatlines (most likely reciever “hold” feature), this can be seen by RCIN.C1 ,C2 …

but THR_FS was not trigged the usual way … you should log more.

You’re probably right that there were some sort of issue with RC, because (if I good rember), I’ve cut the throttle immediately after I’ve noticed the issue, but the ch3in value is kept on high value.
Anyway, I have no idea what was the mechanism of FS trigger since my receiver was not configured to send lower value than THR_FS_VALUE.

Can you please suggest me what type of messages should I add to logging to detect fail safe events better?
BTW dataflash log file seems to be a bit broken - there are IMU messages mixed with UNKNOWN message types on the same lines in in LOG file and MP can’t see them (no idea why too).

Start with at least ERR and EV, I usually have everything enabled.

What bitmask values should be used for it from: … og_bitmask
BTW, my current bit mask value is 65535 (1111111111111111b)