Editing Fly-by-wire (section)

== Rationale ==

Mechanical and hydro-mechanical [[aircraft flight control systems|flight control systems]] are relatively heavy and require careful routing of flight control cables through the aircraft by systems of pulleys, cranks, tension cables and hydraulic pipes. Both systems often require redundant backup to deal with failures, which increases weight. Both have limited ability to compensate for changing [[aerodynamics|aerodynamic]] conditions. Dangerous characteristics such as [[stall (flight)|stalling]], spinning and [[pilot-induced oscillation]] (PIO), which depend mainly on the stability and structure of the aircraft rather than the control system itself, are dependent on the pilot's actions.<ref>{{cite web |url=https://ntrs.nasa.gov/api/citations/19960020960/downloads/19960020960.pdf |archive-url=https://web.archive.org/web/20210602140358/https://ntrs.nasa.gov/api/citations/19960020960/downloads/19960020960.pdf |archive-date=2021-06-02 |url-status=live|title=Pilot Induced Oscillations and Human Dynamic Behavior|last=McRuer|first=Duane T.|author-link=Duane McRuer|date=July 1995|website=ntrs.nasa.gov}}</ref>

The term "fly-by-wire" implies a purely electrically signaled control system. It is used in the general sense of computer-configured controls, where a computer system is interposed between the operator and the final control actuators or surfaces. This modifies the manual inputs of the pilot in accordance with control parameters.<ref name=Crane/>

[[Side-stick]]s or conventional flight [[yoke (aircraft)|control yoke]]s can be used to fly fly-by-wire aircraft.<ref>{{cite news |last1=Cox |first1=John |title=Ask the Captain: What does 'fly by wire' mean? |url=https://www.usatoday.com/story/travel/columnist/cox/2014/03/30/fly-by-wire-cockpit-controls/7026935/ |access-date=3 December 2019 |work=USA Today |date=30 March 2014}}</ref>

=== Weight saving ===
A fly-by-wire aircraft can be lighter than a similar design with conventional controls. This is partly due to the lower overall weight of the system components and partly because the natural stability of the aircraft can be relaxed (slightly for a transport aircraft; more for a maneuverable fighter), which means that the stability surfaces that are part of the aircraft structure can therefore be made smaller. These include the vertical and horizontal stabilizers (fin and [[tailplane]]) that are (normally) at the rear of the [[fuselage]]. If these structures can be reduced in size, airframe weight is reduced. The advantages of fly-by-wire controls were first exploited by the military and then in the commercial airline market. The Airbus series of airliners used full-authority fly-by-wire controls beginning with their A320 series, see [[A320 flight control]] (though some limited fly-by-wire functions existed on A310 aircraft).<ref>Dominique Brière, Christian Favre, Pascal Traverse, ''Electrical Flight Controls, From Airbus A320/330/340 to Future Military Transport Aircraft: A Family of Fault-Tolerant Systems'', chapitre 12 du ''Avionics Handbook'', Cary Spitzer ed., CRC Press 2001, {{ISBN|0-8493-8348-X}}</ref> Boeing followed with their 777 and later designs.{{Citation needed|date=June 2010}}