Private Pilot Anon (twin Beechcraft)
Pilot control was phased out years ago when hydraulic systems were abandoned and fly by wire introduced. Pilot control input has merely become a suggestion to the flight computer to operate the plane's various functions by servo motors. Under optimal conditions, the computer would only override the pilot when unsafe conditions were detected (ie. unsafe attitude, bank, yaw, speed). Sort of like when driving and losing traction and the damn motor governs so you can't dig yourself into a hole. But there are situations where you need that power, so there is an override. Even while under fly by wire, older Boeings had a pilot override for extraneous situations. Years back, in Canada a pilot overrode his system, and slipped his aircraft to rapidly lose altitude for a short landing. I cannot recall the nature of the emergency (phonefagging now). The system of the contemporary Airbus at the time would have vetoed the slip and the aircraft would have probably landed beyond the runway (or crashed).
It seems that Boeing may have eliminated the override feature. Further, a programmer could possibly, if not likely, manipulate the programming to disengage pilot control and fly according to a preprogrammed plan.
For years, I would only fly Boeing when going commercial. I need to investigate more, but I think the Max is the first model without the override system.
Scary stuff.