Boeing is filling in more details about its newest aircraft, still known only by its acronym NMA for New Midrange Airplane. We expect to know even more at the Paris Air Show, which begins the week of June 18. But we're learning that it could open up more route options.

The plane is designed to fit into what Boeing calls the middle of the market. It will be bigger than a 737 and smaller than a 787, but likely to include twin aisles for faster loading and unloading at gates, meaning quicker turnaround for the airlines.

What we do know from briefings with aviation reporters is that Boeing has spoken to some 57 airlines about what they want in an airplane that could become quite common on domestic flights in the U.S., across the Atlantic Ocean to European destinations, and popular in China.

“We’re going to put an airplane in that space with economics that nobody can touch,” Mike Delaney, Boeing’s chief of Airplane Development, said.

Discussions, particularly in the aviation media, began several years ago as more airlines flew Boeing 757s on thinner routes across the Atlantic. Routes such as Seattle to Reykjavik, Iceland, and Newark to Galway, Ireland.

The question: did Boeing make a mistake by ending 757 production in 2005?

Boeing has played down any idea of bringing back the 757 but has increasingly recognized a gap in its product lineup for a jet holding between about 200-240 seats in a multi-class configuration. That would fill a significant gap between the largest 737 and smallest 787 Dreamliner.

"What do we think the space is?” Delaney asked rhetorically.

Boeing makes its jets as families.

The 737 MAX will be made in three sizes and possibly a fourth. The range goes from the smaller MAX 7 at 138 seats, to a proposed MAX 10 at 198 seats in a typical dual class configuration. The 787 is a family ranging from the 787-8 to the 787-10. An NMA family could consist of two sizes of jets.

Delaney said the 787 Dreamliner opened up 140 new routes that nobody was expecting when the plane was designed. Think Seattle to Xiamen, China. These are routes where a 737 would be too small and lack the required range, but a market without enough passengers to fill a Boeing 777 or larger jet for a daily flight. Boeing’s research thinks that the NMA could create even more routes.

“We learned enough on the ’87 to know exactly what we want to do,” Delaney said.

Boeing says it’s talking to the three major engine companies -- General Electric, Pratt & Whitney and Rolls-Royce. Delaney says the plane will push the boundaries of how airliners are constructed.

When will we see it? The tentative target is the mid-2020s, so think 2025 after Boeing begins delivering the 777X in 2020. Where it’s built is also unknown.

What will it be made from? Could the NMA be created out of traditional aluminum or carbon fiber composite? Maybe a combination of both? Delaney says that question could be announced during the Paris Air Show.

“NMA would be a transformational program for the company,” Delaney said.