Failsafe - or not

Today I was going to do some auto tune, and while still in the ground I activated failsafe with some “nice” results… see video. One thing I rest assured. Crash detection works…

Have no idea what happened, I had already done some test flights to sort things and this was completely unexpected…Only difference from previous tests is that I changed battery from 3S to 4S, but adjusted relevant settings.

One can hear the ardupilot Android app during the “flight”…


I’m adding the bin log, copied from the microSD card on the PixHawk. On a recent MacBook Pro, APM Planner 2.08 freezes while downloading log files, but that’s another issue.

Previous tests with a 3S pack went ok




Forgot to add the HW config

Frame DJI F550

Motors and ESC are the E300 kit also from DJI

PixHawk, with the external GPS/Compass unit and the 3DR 433Mhz Telemetry kit

Radio TX - Spektrum DX9 connected to an OrangeRX 800 which is connected to the PixHawk via the SBus to the PixHawk’s RCIN

Yeah, I can’t recommend activating the failsafe on the ground. If your throttle is at minimum it should just disarm. Otherwise it will try to tilt the copter while it is still on the ground, which will cause it to snag things and fall over.

Thanks Jonathan

I fail to see the reason why activating failsafe (or happening by some other reason) should tilt the copter on the ground, even if throttle is not at minimum. Can you clarify?

I managed to get the tlogs and at aprox. 74,xx% of the log (where the video occurred) I see an event of bad compass health followed by the Failsafe and crash at aprox. 76.xx%, if this can help. I’m adding the tlog.