Meanwhile, the airline terminal at Paine Field in Everett is expected to be ready in October.

EVERETT — The new commercial passenger terminal at Paine Field Airport could be finished about the same time the Federal Aviation Administration wraps up the draft of a supplemental environmental study that could determine when the first passenger flight takes off.

The FAA expects to release a draft document in September or October. A 30-day public comment period will follow, an agency spokesman said.

Meanwhile, Brett Smith, founder and CEO of Propeller Airports, expects the building will be completed in October. Propeller is the for-profit company building the commercial terminal.

The start of actual airline service is up to the FAA, which is conducting a supplemental environmental review. The agency in the spring said the entire process could take six to 18 months.

An initial 2012 FAA study approved up to 12 daily airline departures from Paine Field, which is owned by Snohomish County. But now Alaska Airlines, Southwest Airlines and United Airlines are proposing up to 24 daily departures. The expanded scope of operations triggered the supplemental study.

The FAA could find no need for more scrutiny, or it could require a new, lengthier review of traffic, noise and other environmental impacts.

The new terminal is shaping up. Inside, there are baggage conveyors in the check-in and baggage claim areas. A fireplace that will be the focus of a plush waiting area is ready for a flame. Louvers, which mimic the shape of an airfoil and provide shade, are being mounted on the terminal’s upper windows.

Propeller secured a 50-year agreement with Snohomish County more than three years ago to build and operate the two-gate, 30,000-square-foot terminal. By comparison, Sea-Tac Airport has 80 gates.

Paine Field has launched an FAQ page on its website, www.painefield.com, which provides information and updates about commercial service. It says commercial flights should begin later in 2018 or early in 2019, after the airlines obtain the final approvals from the Federal Aviation Administration.

“We are working with Propeller and other stakeholders to commence passenger service as soon as possible,” Arif Ghouse, the Paine Field airport director, said Monday.

At least one airline has begun to advertise its proposed service in a big way. An Alaska Airlines billboard at Evergreen Way and 108th Street SW announces “8 Cities Nonstop? From Everett? Coming This Winter.” But there’s a caveat, in smaller type: “Subject to government approval.”

The United Airlines website now lists Everett or PAE — Paine Field’s three-letter code — as a city it serves, but the airline doesn’t yet offer any booking options.

Many in Snohomish County say they’re looking forward to catching a commercial flight out of Paine Field and skipping a trip to Sea-Tac Airport.

Jeff Harvey, of Lake Stevens, travels for business six to eight times a year. “I had hoped it would start sooner,” Harvey said. “I was hoping they would fast-track it.”

Commercial service would benefit Sharon Sanford, the owner of Renee’s Contemporary Clothing, a women’s apparel and accessories store in downtown Everett.

Sanford regularly flies to Las Vegas and northern California on buying trips, and Alaska Airlines is proposing nonstop flights to Las Vegas, San Francisco and San Jose, among other western cities.

Sanford’s current travel routine involves driving to SeaTac, parking her car at a lot near Sea-Tac Airport and taking a shuttle to the terminal. Paine Field service would eliminate all of those steps, she said.

It’s estimated that about 70 percent of the airport’s initial traffic will be business travelers.

Penny Clark, the owner of Travel Time in Arlington, said commercial service would be “great for me and people in my neck of the woods — Stanwood and Arlington.”

“I don’t think they’re going to have any trouble filling those flights,” said Clark, who has been in business since 1989. “People are anxious for it to begin.”

Janice Podsada: jpodsada@heraldnet.com; 425-339-3097; Twitter@JanicePods.