McDonnell Douglas studied improved, stretched versions of the MD-11 trijet, named MD-12X[1] with a possible lower-front passenger deck with panoramic windows.

In November 1991, McDonnell Douglas and Taiwan Aerospace Corporation signed a Memorandum of Understanding to form a company to produce the new design.

Separating the costly development of the military C-17 airlifter, which had been a drain on the company's resources, from the profit-making production of the MD-80 and MD-11 airliners would make it easier to attract foreign investors for the MD-12X.

[3] Some skeptics believed that MDC launched the project to lure Boeing into paying a higher price for the company.

At the 1996 Farnborough International Air Show, the company presented plans for a new trijet with high-seating and long-range named "MD-XX".

The MD-XX LR was the same length as the MD-11, had seating for 309 in a typical 3-class arrangement and featured a range of 8,320 nmi (9,570 mi; 15,400 km).