Boeing's new-product portfolio is for all intents and purposes full through the rest of the decade with the development of the 737 MAX, 747-8, 777X and the 787 family. But deep within the organization's product development group, the company continues to explore new concepts for the 2020s.

While development priorities and concept details are at the embryonic stage, there is no disguising the obvious gap in Boeing's lineup in the 200-plus-seat sector that was once occupied by the out-of-production 757. Discussions over how, and perhaps even whether, to plug this gap emerged at the recent Singapore Airshow where Boeing acknowledged it is seeing “a lot of interest” for a potential new aircraft larger than the 737 but with less range than the 787.

However, although Boeing concedes there is a market, it cautions that much work is needed before the true size and overall viability of the sector can be established. The one certainty is that while theoretically occupying the seat-capacity market niche once dominated by the 757, the study aircraft would not be a direct successor to the company's single-aisle twinjet, says John Wojick, Boeing Commercial Airplanes global sales senior vice president.

“The market today is not like when the 757 went into service. The 737 Next Generation and 737 MAX will cover the current lower end of that demand, so the question is what is the size of the market and when is it needed?” Wojick says. To find the answers, Boeing is flying “a lot of trial balloons with customers.” Wojick accepts that “there is a niche there,” but says the key is figuring out just how big it is.

Boeing Commercial Airplanes Marketing Vice President Randy Tinseth says: “We think there is maybe a marketplace and we have a lot of interest from a lot of customers in an aircraft that seats between 200 and 300, but which does not need the range capacity of the 787. [There are ongoing discussions] with customers to figure out the market size of what that might become.”

Unlike an earlier Light Twin concept study, which was evaluated in the 2000s as a potential stablemate to the now abandoned short-to-medium range 787-3 version, the newer studies are focusing on range requirements in the 4,000-5,000 nm sectors. The Light Twin, as outlined in early 2009, was provisionally sized around the capacity of the stretched 757-300, but based on a twin-aisle configuration close in scale to the 787-3 (AW&ST Jan. 19, 2009, p. 39). The high-density, medium-range 787-3 variant was shelved in late 2010 after All Nippon Airways—by then the only remaining customer for the type—converted its order for 28 to 787-8s. Although leveraging many elements of the 787 design, the Light Twin was expected to be less dependent on more electric systems and would, for instance, have retained a standard pneumatic system.

The Light Twin concept was aimed at the 2,500-3,200-nm-range market, with seating capacity for 250-260 in a two-class cabin layout and 290-300 in single-class. This would have sized it to replace 757s on classic transcontinental North American routes for which it was originally designed in the late 1970s. However, for some carriers the 757 has since evolved into a longer-range, transatlantic and low-cost operator aircraft as Boeing 737-900ERs and Airbus A321s assumed a greater proportion of the mid- and long-range routes across the U.S. The aircraft now being considered is therefore aimed predominantly at medium routes within markets such as to and within Asia-Pacific, Tinseth adds.

Production of the 757 began in 1981 and—despite a late attempt to stimulate the market with the stretched 757-300—ended in 2004 after 1,050 aircraft were assembled. The last aircraft, a 757-200, was delivered to Shanghai Airlines in November 2005. Although the bulk of 757 routes have gradually switched over to 737-900/-900ERs or A321s, even with the coming debut of the more capable 737-9 member of the MAX family and the reengined A321neo, a true long-range replacement for the 757 has yet to emerge. The 757 sector above 200 seats is “the one segment that is not being served by a new airplane in the pipeline,” says Wojick.

Plans are therefore far from concrete. “We are at still at the stage of finding out what the customer requirements are, what the market size might be and whether it makes sense for Boeing at this stage,” adds Tinseth. An important element of the decision includes assessment of profitability levels for possible production runs at smaller numbers than current family products such as the 737, 787 and 777.