Boeing has outlined plans to develop a new aircraft, with new engines and likely a composite structure, to replace the 737 MAX by 2030.
The aircraft will be slightly larger than the 737 but its shape won't change dramatically from the current fuselage. The push for the new aircraft was being driven by competition from China and elsewhere, chief executive Jim McNerney said.
"By 2030 we will have a new airplane," he said, adding there's "a good chance it will be a composite airplane."
"It will be slightly bigger, there will be new engines. The current look of the planes (shape) won't change dramatically," McNerney said.
China's COMAC is developing the C919 to compete with the 737 and the Airbus A320. The C919 has been delayed until end-2015.
Other competitors include Russia's MS-21 and the slightly smaller Bombardier CSeries.
McNerney said a 737 MAX replacement was needed "because the new entrants would do something like MAX."
Boeing has nearly 100 years of aircraft experience and "we cannot give up that advantage because competing on costs alone would be difficult," he said. "Innovation is the only answer, there's no easy way around."
The Boeing 737 and Airbus A320, seating 150-160 in standard layouts, are the world's most popular jets and the backbone of short-haul fleets worldwide.
Boeing had considered designing a completely new "clean-sheet" design as a successor to the 737 at the start of the decade but abandoned the plan and came up with a revamped version of the 737 known as the MAX after Airbus scored market success with an upgraded version of the A320.
Having invested in an upgrade capable of providing around 15 percent fuel savings thanks to new engines, both companies had previously indicated they would not aim for a complete redesign before 2030.
But McNerney's comments provide further detail to the thinking of the Chicago-based company.
The 737 MAX is a "renovation" of the current 737, with new engines and aerodynamic changes that provide up to 20 percent better fuel efficiency. But the jet is not a new aircraft, and the company now envisions succeeding it in 2030.
Boeing's chief executive has said the company wants to avoid "moon shots" - long-range product developments that take decades to come to market. Instead, Boeing wants to innovate frequently and harvest existing technology in new aircraft, much like tech companies do. By referring to a composite 737 structure, McNerney suggests the successor aircraft will draw from the composite-built 787 Dreamliner, Boeing's latest new aircraft.