Yellowstone is a Boeing Commercial Airplanes project to replace its entire civil aircraft portfolio with advanced technology aircraft. New technologies to be introduced include composite aerostructures, more electrical systems (reduction of hydraulic systems), and more fuel-efficient turbofan engines (such as the Pratt & Whitney PW1000G Geared Turbofan, General Electric GEnx, the CFM International LEAP56, and the Rolls-Royce Trent 1000). The term "Yellowstone" refers to the technologies, while "Y1" through "Y3" refer to the actual aircraft.
Yellowstone is divided into three projects:
- Boeing Y1, to replace the Boeing 737, 757, and 767-200 product lines 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. In early 2011, Boeing outlined plans for a 737 replacement that would arrive in 2020.In August 2011, Boeing pushed back the decision to develop a 737 replacement with the launch of the 737 MAX, an updated and re-engined version of the 737 Next Generation. In November 2014, it was reported that Boeing plans to develop a new aircraft to replace the 737 in the 2030 time frame.
- Boeing Y2, to replace the 767-300 and -400 product lines. It may also replace the 777-200. 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".The Dreamliner competes with the Airbus A330, A340 and later A350 families.
- Boeing Y3, to replace the 777-300 and 747 product lines. Y3 covers the 350–600+ passenger market, and is expected to be the third Yellowstone Project aircraft to be developed. It will compete with the Airbus A380 family as well as the largest model of the A350 family, the A350-1000, scheduled to be introduced in 2017. In June 2010 it was reported that Emirates, which has the largest fleet of 777s, was in discussions with Boeing about plans to develop a new airliner to replace the 777. The Boeing 777-8X and 777-9X were launched by Boeing on November 16, 2013 at the Dubai Airshow in the United Arab Emirates, with 259 orders.