The Boeing 737 was designed in the mid-60s. A lot has changed since then, as the manufacturer's best-selling airplane went through four generations and a dozen variants, but the fundamentals remained the same. And now, as the story of 737 MAX shows, those fundamentals are causing a lot of problems. So, why not build a new aircraft from the ground up?

The first fact we have to discuss is that 737 itself, through constant upgrading, became a replacement for other, even later types. The initial 1967 design was, by modern standards, a regional airplane: with approximately 100 seats and 2,850 km range, it was barely on par with something like current Embraer E-jets. By design, longer ranges and larger capacities were for 757 – Boeing’s other narrow-body airliner.

As a result of the pandemic, the prolonged grounding of the Boeing 737 MAX became a blessing in disguise for airlines. However, as it is set to return soon, the narrow-body might become a headache for airlines once again.

But as the time passed, the 737 was stretched, enlarged and up-engined numerous times, and by the late 90s it had pushed into the 200+ seat 5000+ kilometer market with the new 737NG. The 757 production was discontinued in 2003, in part thanks to airlines buying 737 to do its job. So, replacing 737 would mean replacing 757 too. Something Boeing actually attempted to do numerous times.

Circles of the development hell

Somewhere between the 90s and the 2000s the Yellowstone project emerged: Boeing’s ambitious scheme to overhaul its entire lineup with three aircraft that would utilize the newest technology available. Those aircraft were codenamed Y1, Y2 and Y3.

Y2 became the 787 Dreamliner and Y3, set to replace 747 and larger variants of 777, possibly resulted in 777X – an upgrade instead of a revolution. Y1 was supposed to use a lot of research done for Y2, and thus become a miniaturized Dreamliner: all-composite, fly-by-wire and extremely efficient airliner, universal enough to replace all Boeing’s narrow-bodied aircraft.

In the early 2000s, the plan was to roll out the production model of Y1 by 2015. In 2010, Boeing's patent became public, revealing a glimpse of the new project: a dream of all low-cost airlines and a bold new step for the industry. The aircraft was supposed to have T-tail and nearly elliptical fuselage cross section with twin-aisle 2-3-2 configuration, but retain drag-per-seat and weight-per-seat ratio comparable to single-aisle competitors. A variety of weight-optimization techniques, utilizing the newest composite structures, was explored. According to Boeing Commercial Airplanes CEO Jim Albaugh, the company was already looking into converting their plants from metal to all-composite manufacturing.

But come 2011, the project was shelved. American Airlines (A1G) (AAL)’ decision to go for Airbus 320 certainly played a part in this, as after Boeing got a word of American’s choice, the new 737 generation was rushed into development. Less than four months later, the MAX was ready to take orders.

In 2014, Boeing CEO James McNerney disclosed that the Y1 project was not dead and the 737 MAX would likely be replaced by 2030 with something slightly bigger, but not dramatically different. Some of more innovative ideas may have been discarded, but the premise of all-composite elliptical fuselage remained.