What are fly-by-wire systems?

Fly-by-wire (FBW) systems are semi-automatic, computer-regulated aircraft flight control systems that replace mechanical flight controls with an electronic interface.

When the pilot moves flight controls, those movements are converted into electronic signals, which are then interpreted by the aircraft's flight control computers (FCC) to adjust actuators that move flight control surfaces. Computers also monitor sensors throughout the aircraft to make automatic adjustments that enhance the flight. When equipped with active control sticks, the FCC also uses sensor data to create "tactile cueing" – sensory feedback to the pilot in the form of improved physical "feel" for the aircraft's motions and aerodynamic limits.

Traditional mechanical and hydro-mechanical flight control systems use a series of levers, rods, cables, pulleys, and more which pilots move to adjust control surfaces to aerodynamic conditions. Their "hands on" design gives pilots a direct, tactile feel for how the aircraft is handling aerodynamic forces as they fly. On the other hand, mechanical systems are also complicated to operate, need constant monitoring,
are heavy and bulky, and require frequent maintenance.

Because fly-by-wire is electronic, it is much lighter and less bulky than mechanical controls, allowing increases in fuel efficiency and aircraft design flexibility, even in legacy aircraft. And to prevent flightcritical failure, most fly-by-wire systems also have triple or quadruple redundancy back-ups built into them. Further innovations to the system are also in development, including fly-by-wireless, fly-by-optics, power-by-wire, and more.

 


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