Boeing unveiled the latest member of its 737 narrowbody airliner family on Wednesday when it gave reporters a sneak preview of the new Max 9 model at its assembly line in Renton, Washington. Company officials took the opportunity to report that it expects to complete FAA certification of the smaller Max 8 model imminently.

“The first Dash-9 will be rolling out soon—toward the end of the month,” said Boeing vice president Keith Leverkuhn, who is general manager of the 737 Max program. “Then we’ll have an employee celebration in early March as we head toward first flight, which will likely occur in April.”

Technicians at Boeing’s Renton manufacturing plant are still installing test instrumentation aboard the Max 9 as it sits at the front of an assembly line next to a previous-generation 737 NG-900. The differences between the two aircraft are subtle. The Max 9 nose gear is a little taller, allowing proper ground clearance for the larger CFM International Leap 1-B engines.

Like that of the Max 8, the tail of the Max 9 is conical rather than abbreviated as with earlier variants. At 138 feet 4 inches (42.2 meters) the Max 9 is almost nine feet longer than the Max 8 variant, the wingspan is the same at 117 feet 10 inches (35.9 meters).

In spite of its greater length, increased maximum takeoff weight (194,700 pounds) and longer range (3,280 nm), Boeing touts the Max 9 as much more economical to operate than previous generations of the 737 family, including the its closest relative, the 737-900ER, which also seats 178 passengers in a two-class configuration. Boeing claims that the new Max 9 will deliver seat costs 8 percent lower than those of the rival Airbus A320neo.

The Max 9 is the largest of the new 737s to date. Boeing engineering teams are working on the larger-still Max 10, which Leverkuhn said is now in the initial phase of design. Sales teams are still canvassing airlines as to what they want from this derivative. The Max 7 is the smallest member of the family, equipped to carry 138 passengers in a two-class configuration.

“What we’re really looking at, from a competitive standpoint, is does the airplane meet the missions that the airlines are wanting, given the fact that there’s a competitor out there with a little bit larger airplane [the Airbus A321neo]? The answer is ‘yes,’” he said.

Leverkuhn declined to say whether the Max 10 would end up being presented as the so-called “middle-market aircraft” that has long been anticipated from Boeing. Instead, he said the company is capable of designing and building both the Max 10 and an even larger single-aisle aircraft capable of transcontinental range.