In what could be a great convenience for people traveling to and from Whidbey Island, Alaska Airlines plans to fly passengers out of Paine Field in Everett starting next year.

The Seattle-based carrier made the announcement last Wednesday. That makes Alaska the first airline to commit to using a two-gate passenger terminal working its way through Snohomish County’s approval process.

Executives at Alaska painted the move as a response to rapid economic growth that made Seattle-Tacoma International Airport increasingly busy and Interstate 5 more congested. There’s been demand from businesses as well.

“We’ve thought about Paine Field for a number of years,” said Joe Sprague, Alaska’s vice president of external relations. “Sea-Tac Airport is now sort of bursting at the seams.”

ALASKA SAID that Snohomish County residents, by flying from the Everett-area airfield compared to Sea-Tac, stand to shave 80 minutes off their travel time during peak traffic congestion.

The company plans nine departures a day from Paine Field, starting in the fall of 2018. That would account for roughly half of the capacity at the proposed terminal.

No specific routes are expected to be unveiled until early next year.

“It will be a mix of leisure and business destinations,” Sprague said. “They will be popular destinations, they will be destinations that will be in high demand for people living around Everett … It’s a safe bet, that if we have another winter like the one we just had, there will be one or two destinations in the mix that will be appealing for folks in Snohomish County to escape to.”

In other words, a quick path to sunnier climes.

FOR AT LEAST one expected business route, Sprague said, “driving from Everett to Sea-Tac might take longer than the flight itself.”

The announcement marks another significant step in a decades-long effort to bring regular commercial passenger flights to the county airport.

Propeller Airports hopes to build a two-gate terminal adjacent to the airport’s control tower. Plans show a 29,000-square-foot building. The county issued a grading permit for the project in April. Groundbreaking is expected by summer.

“We’re really happy to have Alaska as our launch carrier,” Propeller CEO Brett Smith said.

Alaska expects to use a combination of Boeing 737 and Embraer 175 jets. Boeing 737-800’s and similar models are regularly used to fly as far as the East Coast. Embraer 175’s are typically used for short- or medium-range trips.

PROPELLER, BASED in New York City, entered into an option-to-lease agreement with the county two years ago. Once the lease takes effect, the county would receive about $429,000 per year in rent. In addition to the lease, the agreement will pay the county 2.5 percent of the facility’s gross revenue during its first four years of operation.

After that, the county would receive 5 percent of revenue for the remainder of the lease. That includes money from air service as well as parking.

Many people in Mukilteo have spent years fighting the idea, raising concerns about noise, traffic and other aspects of their quality of life. They lost key court battles during the past couple of years.

On Wednesday, Mayor Jennifer Gregerson led a press conference in front of City Hall.

Gregerson called Alaska’s announcement premature. The city continues to challenge the proposed terminal in court. Mukilteo is awaiting a state Supreme Court decision on whether to accept its appeal of the county’s 2015 lease agreement. Mukilteo alleges the agreement should be scrapped because the county failed to perform a full environmental study of likely impacts in terms of noise, traffic and other areas.

“I want to reassure my community that we will continue to press for important protections for our quality of life, no matter how our appeal goes,” Gregerson said.

MUKILTEO’S MAYOR said her city already has helped to limit the hours of operations and flight paths from the airport. The city also is demanding that the county and Propeller compensate for any traffic impacts, if the terminal moves ahead.

But many local officials were elated.

“Businesses will have easier access to major markets and leisure travelers can skip the commute down south, saving time and fuel,” County Executive Dave Somers said. “For decades, Alaska Airlines has been a responsible neighbor in our region, and we welcome them even closer to home at Paine Field.”

Everett Mayor Ray Stephanson has been among the strongest supporters of bringing regularly scheduled commercial flights to his city’s doorstep.

“Alaska understands the local market, so having our Seattle-based airline be the first to provide scheduled passenger service from Everett just confirms the value commercial flights will bring to the local economy,” Stephanson said.

ALASKA’S NEW operations aren’t expected to displace any of its existing business from Bellingham International Airport — or anywhere else, Sprague said.

Some routes are likely to overlap with 83 locales Alaska already serves nonstop from Sea-Tac.

“It’s tough to compare to anything else in our network,” he said.

The new Paine Field terminal could handle up to two dozen takeoffs and landings per day. Paine Field already averages more than 300 daily takeoffs and landings, mostly from general aviation and aerospace companies.

• Noah Haglund is a reporter for The Herald in Everett.