This is military, but I seem to remember an early (1950'ish) Vickers being the first 'commercial' style aircraft. Anybody?
http://www.globalsecurity.org/milita...rcraft/f-9.htm
In 1954, flight tests of the first fly-by-wire aircraft, a modified F9F Panther jet, were initiated at Langley. The primary objective of the tests was to evaluate various automatic control systems, including those based on rate- and normal-acceleration feedback. However (as is the case in many research investigations), the most valuable result of the flight test was related to secondary objectives—in this case the introduction and evaluation of fly by wire and a sidestick controller for pilot inputs.
In a serendipitous approach, Langley researchers decided to avoid the relatively large expense and time required to modify the existing hydraulic flight control system for the F9F. Instead they chose to implement an auxiliary system based on a fly-by-wire analog concept and a small (4 in.) sidestick controller mounted at the end of the armrest at the side of the pilot. The sidestick controller was used as the maneuvering flight controller throughout the investigation. Rapid and precision maneuvers such as air-to-air tracking, ground strafing runs, and precision landings were evaluated.