Editing Fly-by-wire (section)

=== Airbus/Boeing ===
{{Main|Flight control modes}}

Airbus and Boeing differ in their approaches to implementing fly-by-wire systems in commercial aircraft. Since the [[Airbus A320 family|Airbus A320]], Airbus flight-envelope control systems always retain ultimate flight control when flying under normal law and will not permit pilots to violate aircraft performance limits unless they choose to fly under alternate law.<ref>{{cite magazine|url=https://www.popularmechanics.com/flight/a3115/what-really-happened-aboard-air-france-447-6611877/ |title=Air France 447 Flight-Data Recorder Transcript – What Really Happened Aboard Air France 447 |magazine=Popular Mechanics |date=6 December 2011 |access-date=7 July 2012}}</ref> This strategy has been continued on subsequent Airbus airliners.<ref>Briere D. and Traverse, P. (1993) "[http://personales.upv.es/juaruiga/teaching/TFC/Material/Trabajos/AIRBUS.PDF Airbus A320/A330/A340 Electrical Flight Controls: A Family of Fault-Tolerant Systems] {{webarchive|url=https://web.archive.org/web/20090327095042/http://personales.upv.es/juaruiga/teaching/TFC/Material/Trabajos/AIRBUS.PDF |date=27 March 2009 }}" Proc. FTCS, pp. 616–623.</ref><ref>North, David. (2000) "Finding Common Ground in Envelope Protection Systems". ''Aviation Week & Space Technology'', 28 Aug, pp. 66–68.</ref> However, in the event of multiple failures of redundant computers, the A320 does have a mechanical back-up system for its pitch trim and its rudder, the [[Airbus A340]] has a purely electrical (not electronic) back-up rudder control system and beginning with the A380, all flight-control systems have back-up systems that are purely electrical through the use of a "three-axis Backup Control Module" (BCM).<ref>Le Tron, X. (2007) [http://www.fzt.haw-hamburg.de/pers/Scholz/dglr/hh/text_2007_09_27_A380_Flight_Controls.pdf A380 Flight Control Overview] Presentation at Hamburg University of Applied Sciences, 27 September 2007</ref>

Boeing airliners, such as the [[Boeing 777]], allow the pilots to completely override the computerized flight control system, permitting the aircraft to be flown outside of its usual flight control envelope.