flybywire

Fly-by-wire (FBW) is an aircraft control system that replaces manual flight controls with an electronic interface. Pilot inputs at control devices such as side-sticks or yokes are converted into electrical signals, processed by flight control computers, and used to actuate the aircraft's control surfaces via hydraulic or electric actuators. In many airliners, the control laws implemented by the computers enforce protections and performance limits that influence how surfaces respond to inputs.

History and development: FBW first appeared in military aircraft and experimental programs in the 1960s–1980s and became widespread in commercial aviation with the Airbus A320 family entering service in 1988. Since then, most new airliners have FBW systems, with newer generations adding more advanced fault tolerance and software-driven behavior.

Design and operation: Modern FBW systems rely on multiple redundant flight control computers and data buses. Sensors provide air data, attitude, and angle-of-attack information. The computers apply flight control laws (e.g., normal, alternate, or direct) to map pilot commands into surface movements, while monitoring for stick shaker protection, gust loads, and stall margins. Actuators shift the control surfaces accordingly. Redundancy and self-test features maintain control in the event of a component failure.

Advantages and limitations: FBW can reduce weight, provide smoother handling, enhance stability, and offer envelope protections that prevent dangerous maneuvers. It also enables advanced flight-augmentation features such as stability augmentation and auto-trim. Limitations include software complexity, potential failure modes requiring rigorous validation, and cybersecurity considerations for networked systems. Maintenance focuses on software updates and fault isolation.

Examples: Airbus has used FBW extensively on the A320 family, A330/A340, A380, and A350. Boeing also employs FBW in models such as the 777 and 787 Dreamliner. Ongoing developments include more distributed computing and enhanced automation.