Boeing is abandoning its long-running effort to devise a successor to the 737, driven back to the drawing board by the lack of existing technology that can deliver the huge leap in performance airlines want for a next-generation single-aisle aircraft.

The decision to disband the 737RS (replacement study) design project, because it fell short of critical performance targets, has implications beyond Boeing. It will likely influence how Airbus moves forward on its A320 replacement effort, the A30X. For airlines, it means an even longer wait until a 737 or A320 follow-on hits the market.

For Boeing, the focus now switches to more fundamental research into aerodynamics, composites and other advanced alloys and hybrid materials, systems and propulsion in the hope that concepts will emerge to meet the challenge.

The manufacturer openly admits the change of strategy, saying, "We know customers are demanding really high targets for this aircraft, and we know that with the state of technology, we're not going to get there anytime soon." As a result, Boeing adds, "We're focusing on technology efforts and reducing the aircraft design effort while the technology matures."

The transformation of the 737RS project into a more sweeping technology study effort is sparking industry speculation that this will inevitably push any prospective development of a 737 successor toward 2017-19. Boeing declines to be more specific on the impact of the decision or the potential for further slippage. It simply says, "We expect the rate of this technology development to be available in the latter part of next decade, and we've said this will be no earlier than 2015."

Boeing's 737RS study emerged from the product development group's P-1 project of the late 1990s, and was later absorbed as a subset of the Yellowstone project. Further details came out in early 2006, when Boeing named key executives to the project, including Mike Cave, vice president for airplane programs, and Carolyn Brandsema, head of aircraft and production system studies.

At the time, Boeing was still targeting a 2012-15 entry-into-service window, and was starting to explore splitting the project, renamed 737RS, into two portions covering a 90-120-seater and a larger family bridging the gap between 125 seats and the lower range of the 787.

Studies to date combining the best technology advances in materials, propulsion, aerodynamics, structures and systems have produced results that, according to industry sources, fail to get even halfway toward Boeing's original operating cost, fuel burn and emissions goals. The most realistic design scenarios have produced overall operating cost improvements of only around 10% versus current 737-700/800 performance.

Boeing has not publicly stated the 737RS targets, but they are believed to be cost reductions in the 20-25% range. A company official clarifies, however, that "you can't just do a shrink of the 787; it's not as easy as that because of the different missions, higher cycles and shorter range. You can't shrink the 787 because of the systems. You need volume to handle the systems on the 787. With this study, we really need breakthroughs."

Airbus also has backed away from any earlier commitments for its A320 successor, the A30X, which was similarly aimed at the 2012 entry-into-service timeframe when originally disclosed as the New Short Range (NSR) project around 2005. The aircraft maker now forecasts a 2018 service entry at the earliest.