What is ‘fly by wire’?

Aircraft control surfaces, located on the wings, the rudder and horizontal stabiliser at the rear of the aircraft, were originally connected to the pilots by a series of cables and pulleys. Pilot action on the control wheel or stick, would move the control surface, which was some distance away, by the mechanical linkage between the two.

Airbus became the first manufacturer to remove this mechanical linkage and instead use an electronic interface between the pilots and the control surfaces. The pioneering A-320 aircraft did away with mechanical linkages, with pilot input being converted to digital electrical signals, that were relayed to the control surfaces vie electrical circuits, the ‘wires’ in ‘fly by wire’ or FBW.

The allowed a great deal of weight saving and also permitted increased use of computer-controlled techniques to optimise flight. The popularity and reliability of the system forced Boeing to follow suit, with the B-777 being the first of their products to incorporate fully digital FBW controls. The B-787 uses a similar system, as does the entire stable of Airbus aircraft.