Flight termination - Always send flag to IO without checking the circuit breaker. The circuit breaker is used inside IO to decide if it has to go into failsafe if FMU dies and also controls is the FailureDetector sets the force_failsafe flag. The other sources of flight termination (rc loss, geo fence, ...) are not disabled by the circuit breaker

src/modules/px4iofirmware/mixer.cpp

@@ -235,6 +235,7 @@ mixer_tick(void)
 		should_arm &&
 		/* and FMU is initialized */
 		(r_status_flags & PX4IO_P_STATUS_FLAGS_FMU_INITIALIZED)) {
+		/* FMU is then dead -> force failsafe */
 		PX4_ATOMIC_MODIFY_OR(r_setup_arming, PX4IO_P_SETUP_ARMING_FORCE_FAILSAFE);
 	}