Boeing has ruled out developing a significantly larger 200 seat 757-sized aircraft to replace today's Next Generation 737s, and will instead focus its product development studies around an aircraft "modestly bigger" than today's 145 to 180-seat 737-700 and -800.

"We've had a lot of people encouraging us to do a much larger narrowbody," said Boeing CEO Jim McNerney at his company's 2011 investor day, but ruled out a 757-sized replacement as the company's direction.

"The first order of business is to replace the heart of the market, which may be slightly bigger than it is now, but not a huge step function bigger," said McNerney. "Which doesn't mean that someday we wouldn't address the market segment above the -700 -800 sized airplane."

"That is another market segment we could either come down on 787 or move up from narrowbody, we're sorting through that right now," he added, suggesting another 787 variant or further stretch of its new jet.

McNerney said a formal decision on a new narrowbody would be made in the next nine months, ruling out an announcement at June's Paris Air Show as it had previously intended.

"We're going to retain the ability to re-engine [the 737] if this new airplane doesn't come together in the next nine months or so. We think it will," said McNerney.

"As a betting man that's where I think it will end up, but we're going to retain the ability to do both and make a decision when we have to make a decision going forward."

The new narrowbody, which would enter service in 2019 or 2020, would aim to provide a 20% improvement in fuel burn and a cash operating cost improvement "well into double digits," said Boeing Commercial Airplanes CEO, Jim Albaugh, who added that a re-engined 737 would be available in 2016 or 2017 and preserve an 8% cost of ownership margin over the A320neo.

Albaugh said the technology is available to deliver a "step function improvement" in economic performance with a new narrowbody through aerodynamic, material and engine technology.

Referring to production considerations for a new aircraft, he said: "How do you take an airplane that is probably composite and how do you ramp it up from zero airplanes a month to 40, 50 or 60 [per month] and how do you do that in a short period of time?"

He added that Boeing is looking to other high-rate manufacturing industries to design the production system for the new jet, aiming to reduce the amount of tooling, eliminate autoclaves for composites and minimise drilling requirements for structures.

Reflecting on the applied lessons from the 787 programme, Albaugh said: "In the past we've adapted airplanes to the production system, this time we need to design an airplane and a production system together and that's precisely what we're trying to do."

Source: Air Transport Intelligence news