In the mid-1970s, Airbus began development of the A300B9, a larger derivative of the A300, which would eventually become the A330. The B9 was essentially a lengthened A300 with the same wing, coupled with the most powerful turbofan engines available. It was targeted at the growing demand for high-capacity, medium-range, transcontinental trunk routes. Offering the same range and payload as the McDonnell Douglas DC-10 but with 25 per cent more fuel efficiency, the B9 was seen as a viable replacement for the DC-10 and the Lockheed L-1011 TriStar trijets. It was also considered as a medium-ranged successor to the A300.