Fly-by-Wire — Fly-by-Wire Flight Control System

How Fly-by-Wire Works

In a fly-by-wire (FBW) system, moving the sidestick, yoke, or rudder pedals does not directly move a control surface through a mechanical connection. Instead, the input is converted into an electrical signal, processed by flight control computers, and then sent to actuators at the control surfaces. The computers can also incorporate feedback from the aircraft's sensors, comparing the desired flight path or surface position against the actual one and adjusting continuously.

Why It Was Adopted

Design Philosophies

Different manufacturers have taken different approaches to how much authority the flight control computers retain in extreme situations:

History and Adoption

Fly-by-wire technology was first proven in military aviation, with the F-16 becoming one of the first production aircraft to use fly-by-wire for all of its flight controls in the 1970s. In commercial aviation, the Airbus A320, introduced in the late 1980s, was the first airliner to use a full digital fly-by-wire system as its primary flight control architecture, and the technology has since been adopted across most subsequent Airbus and Boeing widebody and narrowbody families, including the Boeing 777, typically using triple- or quadruple-redundant computer channels with a limited mechanical backup in some designs.

Why It Matters

Fly-by-wire has become the standard flight control architecture for modern airliners because it combines weight savings with safety features such as envelope protection, while giving manufacturers more flexibility in aircraft handling characteristics than purely mechanical or hydromechanical systems allow.