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For the first time, Boeing has begun building its most popular narrowbody plane in Everett.
The company on Monday turned on its North Line, the fourth 737 MAX production line and the first MAX line outside its Renton factory, allowing Boeing to increase the number of MAX planes it churns out each month and bringing new life to previously unused space in its largest manufacturing facility.
The North Line represents a $1 billion investment from Boeing, including upgrades to its Everett facility, workforce training and changes to its production system, the company said. The North Line will start operating with 1,000 employees and grow its workforce as it increases its production rate over time, according to Jennifer Boland-Masterson, senior director for the 737 North Line.
Boeing loaded its first soon-to-be plane on the production line this week, with two fuselages rolling into the Everett factory, and celebrated the grand opening on Friday.
Boeing has been moving toward that milestone since January 2023, when the company announced it would add to its three existing MAX production lines. The new line will take the space formerly used to build Boeing’s widebody 787 Dreamliner, a work package that Boeing moved entirely to its North Charleston, S.C., facility in 2021, dealing a significant blow to Washington and the union members who built the plane here.
Since then, Boeing has used the unoccupied factory space to repair other planes, including flawed 787 Dreamliners. But the factory, the largest manufacturing building in the world, has continued to sit with unused space.
This week, Boeing added to Everett’s workload.
Adding MAX capacity
The North Line will help Boeing increase its monthly MAX production, something the company has focused on heavily following years of setbacks, including two fatal 737 MAX crashes in 2018 and 2019, the COVID-19 pandemic, a nearly catastrophic panel blowout in 2024 and a Machinists strike in Boeing’s Puget Sound factories that fall.
Boeing is in the process of ramping up to produce 47 MAX planes per month, an increase from 42 and before that 38. The Federal Aviation Administration capped Boeing’s monthly MAX production at 38 planes after the panel blowout, and approved the company’s first rate increase since the incident in October.
Boeing won’t need the North Line to produce 47 MAXs per month, but it will tap into the extra capacity as it starts increasing to 52 planes per month.
The North Line will start slowly, with Boeing operating at a “low rate of production” for the first 10 airplanes to move through the new line, according to Boland-Masterson. That’s meant to build in wiggle room to make sure the line operates as expected and space to address any wrinkles.
Boeing is also still working with the FAA to add the North Line to its production certificate. The manufacturer can’t deliver any planes it rolls off the North Line until it receives that regulatory approval.
To do so, Boeing must complete two types of reviews: a process called production certification management, where the FAA validates each station in the factory as the fuselage moves through the production line, and conformities, where the regulator observes specific tasks.
Boeing declined to put a timeline on FAA certification for the North Line, but Boland-Masterson said during a tour this week she hopes it will be finalized in 2026.
The first two planes built on the North Line will be 737 MAX 10s, Boeing’s largest MAX variant that has yet to be certified to carry passengers by the FAA. The very first plane to roll off that line will be delivered to WestJet, a Canadian carrier.
The next two planes on the North Line will be 737 MAX 8s, one of the MAX models already in service. The North Line will be able to build 737 MAX 8s, 9s and 10s, but doesn’t currently have the capability to build the MAX 7, the smallest variant and another model that has yet to be FAA certified.
Apart from the North Line, Boeing also builds its 777 and 767 planes in Everett, as well as the KC-46A refueling aircraft. It will also build its 777X family of planes, another program that has not yet been certified by regulators.
Inside the factory
The North Line will function in the same way as the lines in Renton, following the same 10 “flow days,” Boeing’s internal language to describe each stop the fuselage will make through the factory and specific tasks to complete at each station. The flow days are loosely tied to one day of work, but the fuselage doesn’t have to move every day if tasks aren’t yet complete.
In Renton, the fuselages move through a U shape, moving down the length of the factory through flows days 1 through 4, then making a wide turn and traveling back the same way, on the opposite side of the factory, for flow days 5 through 10.
On Everett’s North Line, the fuselage enters the factory on the north end and moves across the floor for flow days 1 through 4. It then travels toward the south end of the factory for flow days 5 through 10.
Then, it rolls out of the facility for preflight tasks that can’t be done inside, like adding fuel to the plane. The finished plane will then go to Boeing’s Everett Delivery Center for the customer handoff.
There are four additional spaces near flow day 10 where Boeing can hold planes if it needs to complete a task, wait for a part or perform a repair. Boeing is calling those “slant positions.”
Two of those slots are designated for adding in what Boeing calls “complex interiors,” or certain seat configurations that require more work than can be accomplished in the usual flow day structure.
The fuselages for MAX lines at both factories are built in Wichita, Kan., at the former Spirit AeroSystems site that is now part of Boeing, and shipped to the Puget Sound region via train. They arrive to the factory on a specific transportation tool and are lifted by crane into the first flow day position.
The structural elements for the airplane’s wings are built at the Renton site and are sent via trailer to Everett, where mechanics will finish building the wings and join them to the fuselage.
Because the space was once used to build the 787, a much larger plane than the 737 MAX, the North Line has about 20% more room than the MAX lines in Renton, said Boland-Masterson.
That extra space will allow Boeing to fit more of its largest MAX variant than would be possible in Renton, Boland-Masterson continued. The North Line could be filled entirely with 737 MAX 10s, nose to tail, while the Renton lines would require staggering the plane models; a 737 MAX 8 would have to follow a MAX 10.
Though it can hold all MAX 10s, Boland-Masterson said the company is “absolutely not” producing just the largest variant on its new line.
Separated by more than 30 miles, Boland-Masterson said the Renton and Everett MAX lines will operate as a “partnership.”
Leadership from both factories will report to Katie Ringgold, vice president and general manager for the 737 program. North Line employees will be about 50% new hires and 50% current Boeing employees transferring from other sites; new workers will train in Renton. The factories will source their own parts, though from the same suppliers, and, if needed, could pass a part from one factory to the other, Boland-Masterson said.
Importantly, she emphasized, the company will follow the same safety and quality plan that it implemented after the panel blowout in 2024 at both sites. She pointed specifically to Boeing’s “move readiness” criteria, a set of metrics it uses to determine if the fuselage is ready to move to the next flow day.
Renton “perfected” that plan, Boland-Masterson said, and we will follow that script.”
“This is one team. We’re going to lean on each other.
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