The first of these projects, Y2, entered service as the Boeing 787. The second project, Y3, is expected to enter service as the Boeing 777X. The Y1 project was cancelled in favor of the re-engined Boeing 737 MAX.
Boeing Y1, to replace the 737 and 757 product lines.[2] The Y1 covers the 100- to 250-passenger market, and is expected to be the second Yellowstone Project aircraft to be developed. Boeing submitted a patent application in November 2009, that was released to the public in August 2010, that envisions an elliptical composite fuselage, and likely signals the company's planning for the 737 successor.[3][4] In early 2011, Boeing outlined plans for a 737 replacement that would arrive in 2020.[5][6] In August 2011, Boeing announced the 737 MAX, an updated and re-engined version of the 737, rather than progress with Y1 concepts.[7]
Boeing Y2, to replace the 767 product line.[8] It covers the 250- to 350-passenger market, and was the first completed Yellowstone project, coming to fruition as the Boeing 787 Dreamliner. Y2 initially referred to the highly efficient, more conventional, baseline aircraft for the Sonic Cruiser, which was project "Glacier".[9] The Dreamliner competes with the Airbus A330neo.
Boeing Y3, to replace the 777 and 747 product lines. Y3 covers the 350–600+ passenger market. The Boeing 777X is largely considered the end result of the Y3 program, which was launched by Boeing on November 16, 2013. The 777X competes with the Airbus A350.
