Delivery of the 561st Airbus A300 next month marks completion of the European manufacturer’s long march to becoming a successful competitor to its U.S. rival, Boeing, in the commercial aircraft market. It has developed, certified, marketed and completed profitable production of its initial design and embarked on a successor project.

Meanwhile, alongside manufacturing of the A300–the world’s first twin-aisle twinjet airliner– Airbus has certified a series of jetliners ranging in capacity from 100 to almost 600 passengers. Indeed, unless and until Boeing enters the market for airliners with more than 500 seats, only Airbus offers a complete jetliner family, from the twin-engine, single-aisle A318 to the quad-engine, quad-aisle A380 very large airliner.

The A300 story is very much that of Airbus: the design actually being three or four years older than the company, which began as a European consortium involving British, Dutch, French, German and Spanish manufacturers. Initiated under the name “European Airbus,” the A300 preceded the A310, the single-aisle A320 series, the A330 twinjet, the four-engine A340 and the A380. Overall, Airbus has taken orders for almost 7,300 jetliners and delivered more than 4,600.

In 2003, now-retired Airbus market-forecast vice president Adam Brown said the company succeeded because it addressed airline requirements with state-of-the-art technologies. “It was evident we could penetrate a market wholly dominated by American suppliers only if we offered clear competitive advantages. This led us to focus very carefully on customer needs and widespread application of advanced technology wherever it would provide clear benefits in safety, performance capability and/or profitability,” he said.

With carriers seeking 15-percent-lower direct operating costs per seat than existing designs, Airbus aimed to provide an intermediate twin-engine aircraft to compete against Boeing 727, Douglas DC-10 and Lockheed L-1011 trijets, but with capacity to hold side-by-side LD3 cargo containers below the floor.

One innovation for a twin-jet was triple hydraulic and electric systems, while another was the A300’s advanced aft-loaded wing section. The design also featured automatic throttles controlling thrust at all speeds, wind-shear detection to ensure availability of full power and equipment permitting crews to fly at maximum-lift angle of attack. A tall undercarriage ensured ground clearance beneath the large underwing pylon-mounted fan engines in a layout that has become de rigueur in all sizes of twin-jet airliners.

Airbus took the project’s identity from the initial 300-seat capacity, but in 1968 program director Roger Béteille redesigned it with 250 seats, retaining the numeral but introducing a “B” suffix to denote a second basic design. The suffix was subsequently dropped, although Airbus letters were used to denote A300F freighters and A300C passenger/ cargo models.

A fuselage diameter of 222 inches provided what, until the recent advent of the broader A350XWB “extra widebody,” Airbus has always regarded as a “magic” dimension that was successfully and successively employed for the A310, A330 and A340.

The smaller A300B was some 15 percent lighter than in 300-seat guise and it provided an improved platform for 50,000- pound-thrust Pratt & Whitney JT9D, Rolls-Royce RB.211, and General Electric CF6 engines. Formal agreement to proceed among government and industry officials in France and Germany was signed here at Le Bourget during the 1969 Paris Air Show.

The prototype A300B1 made its maiden flight on Oct. 28, 1969, with the stretched A300B2 following in April 1970 and the heavier, long-range B4 in December 1974. Air France flew the first flights on May 23, 1974, but orders came slowly–only 36 during 1974 and 1975 and just one in 1976. Two later years–1982 and 1986–saw single-digit orders before airline requirements virtually dried up after 1992.

The basic A300 was developed in other variants, notably the short-body 200-seat A310 featuring a smaller wing and re-worked rear fuselage to accommodate two extra seat rows and additional underfloor containers or extra fuel.

Other developments included Krueger flaps for hot-and-high operations, a side cargo door for convertible freight operations and, more significantly, the “forward-facing crew concept” that gave the world the two-pilot airliner cockpit.

Initially, U.S. airlines resisted the European design, sometimes ordering 727s despite prospective noise legislation that would outlaw the older–but home-produced–airframe. When Eastern Airlines finally leased four aircraft, Airbus had to guarantee lower fuel burn, but the operator ordered 23 aircraft in 1978 after proving fuel costs almost 30 percent lower than for the 727. Other orders that year saw cumulative A300 sales double to 126, before doubling again in 1979 to 253 overall and putting the aircraft well on the way to breakeven.

Subsequently, Airbus launched the larger, 266-seat A300-600, which competed against the stretched Boeing 767-300, then the longer range -600R that introduced center-of-gravity management and a tailplane fuel tank, and finally the A300-600F freighter.

Despite reduced orders since the early 1990s, there has been sufficient airline interest, mainly from cargo operators, to sustain A300 production until this year. For Adam Brown, the success has been ironic, given that initially the twin-aisle, twin-engine concept had been seen by many as “almost heretical.”