Final answer:
Simultaneous movements of side sticks by pilots in a fly-by-wire aircraft are processed by flight control computers, leading to an average, prioritization, or a dual input warning.
Step-by-step explanation:
When both pilots move their side sticks simultaneously in a modern aircraft with a fly-by-wire system, the inputs are usually processed by the aircraft's flight control computers to determine the resulting action. Depending on the specific design and logic of the system, it may average the inputs, prioritize one (e.g., Captain's input over First Officer's), or trigger a dual input warning. The exact reaction can vary from one aircraft model to another.
Moving their side sticks simultaneously means that both pilots are giving the same input to the control system of the aircraft at the same time. In an aircraft with a fly-by-wire system, this would result in the control system combining the inputs from both pilots and controlling the aircraft accordingly. The exact outcome will depend on the specific aircraft and the implementation of the fly-by-wire system.