syseng68k, PLCs are slow, dumb, ladder logic tools that are dumb enough to be 100% predictable in their operation. That is why they are used in industry and safety critical applications. You seem to be telling me that modern aircraft software is falling into feature creep to the point they're using multi-tasking and priorities. Please tell me I'm not putting my life in the metaphorical hands of a potential priority inversion or interrupts left off for too long. And I hope the CPUs and hardware on the flying planes are used at about 10% of their ultimate capacity if they are using multi-tasking.
Dumb silly state machines do have a wonderful place in safety applications.