Airbus A320 (1987) — the fly-by-wire revolution

1987·Mach 0.78 (~829 km/h)·2× CFM56 or IAE V2500 turbofans, ~120 kN each·7, in two dissimilar designs (ELAC, SEC, FAC)·~150 (typical two-class)

· THE STORY

The computer between pilot and wing

The A320 looks like an ordinary airliner, and that is the point: its revolution is invisible. Pull back on its small sidestick and no cable moves — the stick sends an electrical request to flight-control computers, which decide how to move the wings and tail. The computers also refuse politely: they will not let the aircraft stall, overspeed or overbank, no matter what the pilot asks. Nearly every airliner designed since works this way.

Mach 0.78 (~829 km/h)Cruise speed2× CFM56 or IAE V2500 turbofans, ~120 kN eachEngines

· WHY IT MATTERED

Signals instead of cables

For eighty years a pilot’s controls were connected to the wings by steel cables, pulleys and pushrods running the length of the aircraft. The A320 replaced almost all of it with wires carrying signals to computers, and computers commanding hydraulic actuators at each surface — lighter, more precise, and able to move each surface for reasons of its own, like smoothing gusts the pilot never felt.

· WHY IT MATTERED

The envelope has a fence

The computers know the aircraft’s limits — stall angle, maximum speed, structural g — and simply will not cross them. A pilot escaping windshear can snap the stick fully back and hold it there: the aircraft gives its maximum climb performance, right at the edge of the stall, without stalling. Before fly-by-wire, that manoeuvre relied on nerve and feel; now it is guaranteed by design.

· WHY IT MATTERED

Computers that vote, and fail politely

No single computer is trusted. The A320 carries seven flight-control computers of two different designs, written by separate teams, cross-checking each other. If one disagrees it is outvoted; if several fail, the aircraft steps down through simpler control laws and can still be flown. Redundancy through disagreement is now the template for every safety-critical system, in aircraft and beyond.

GO DEEPERComputers that vote — how fly-by-wire earns trust →

· WHY IT MATTERED

One cockpit for a whole family

Because the "feel" of the aircraft is computed rather than mechanical, Airbus gave the A320’s cockpit and handling to every aircraft it designed afterwards — a pilot moves between the A320 and the giant A380 with days of training instead of months. That common type rating changed airline economics, and helped make the A320 family the best-selling airliner in history.

· TRY IT

Fly-by-wire vs direct linkage

Two aircraft, one stick. The mechanical aircraft does exactly what you command — including flying straight past the stall. The fly-by-wire aircraft filters the same command through its envelope protection: push it as hard as you like, it rides the limit and never crosses it. Add a gust and watch the computers correct before you could.

Readout

Direct: angle of attack2.5°

Direct: lift (vs cruise)1.00×

FBW: angle of attack2.5°

FBW: lift (vs cruise)1.00×

The fly-by-wire aircraft rides the lift curve to α-max and sits there — maximum lift on demand, stall unreachable. The direct aircraft crosses the stall line, loses its lift and porpoises as the held stick drags it back through the break, exactly what envelope protection was invented to end.

GO DEEPEROpen the full demo →