TSA will use Sea-Tac Airport's north checkpoint for PreCheck, a new expedited screening program it is testing at 28 airports this year as it moves away from one-size-fits-all security checks.

Thousands of Alaska Airlines frequent fliers and others labeled “low-risk” travelers by the U.S. government will get a fast pass through security lines at Sea-Tac Airport starting April 24.

Alaska Airlines sent selected customers a letter Monday notifying them that the Transportation Security Administration (TSA) will use the airport’s north checkpoint to test PreCheck, an expedited screening program it’s rolling out at 28 U.S. airports this year as it moves away from one-size-fits-all security checks.

Those eligible — for now, only members of Alaska’s frequent-flier program invited by the airline and preapproved by the TSA, as well as members of the Nexus, Global Entry and Sentri expedited border-crossing programs run by U.S. Customs and Border Protection — will speed through a special lane without taking off their shoes and belts or removing laptops and liquids from carry-ons.

They’ll also walk through metal detectors, bypassing the full-body scanners that have raised concerns over privacy and low-level radiation emissions.

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PreCheck includes a random-screening component, so agents may still ask a few people to remove shoes and belts. But for the most part, those on the approved list will be sailing through. As of early April, 700,000 passengers participated in PreCheck at 12 U.S. airports testing the program.

“I really see the benefit of this as being one fewer annoying routine to have to go through at Sea-Tac,” said Frank Catalano, of Seattle, an Alaska Airlines MVP Gold customer notified by the airline this week that he could use PreCheck. “Starting a trip — which is stressful, even best-case — a little less hassled and a little less inconvenienced will likely make the entire trip better.”

Alaska Airlines passengers will be able to use PreCheck only at Sea-Tac, although Alaska said it is working with the TSA to add other airports this year, including Portland in May, then Anchorage and possibly Los Angeles.

That would be good news for Mark Van Lommel, an Alaska frequent flier who lives in L.A.

“I’m looking forward to not needing to remove my shoes, belt, coat, laptop and toiletries and maintaining a sense of decency when I fly again,” he said in an email.

TSA spokeswoman Lorie Dankers couldn’t say when the agency will open PreCheck to other airlines at Sea-Tac, or when the general public might become eligible to apply.

“Pre-check allows us to focus our (screening) efforts on people we know nothing about,” she said.

But there’s pressure for the government to quickly make the program more inclusive.

“What we really think TSA has to do is step it up and find a way to enroll a large number of legitimate travelers, not just airline customers,” Roger Dow, CEO of the U.S. Travel Association trade group, said in a recent phone interview.

To participate, high-mileage members (MVP Gold) of Alaska’s frequent-flier program agree to allow the airline to submit their names, genders and birth dates to the government for pre-screening.

Nexus, Global Entry and Sentri members supply more-detailed information and submit to a personal interview, photo and digital-fingerprint scan as part of the approval process for those programs.

Any U.S. citizen can apply for an expedited border-crossing card, and Alaska will continue to invite more frequent-flier members into PreCheck, Dankers said.

Airlines automatically send the frequent-flier information to the TSA when passengers make reservations. Nexus, Global Entry and Sentri members enter their ID numbers in the “Known Traveler Number” field when booking, or can add their ID numbers to their frequent-flier profiles.

Expedited clearance is on a per-flight basis, so travelers don’t find out that they’re eligible to use the special lane until they check in at the airport and a TSA agent scans a bar code on their boarding passes. PreCheck is just one of the changes TSA is making to airport security.

To reduce the number of pat-down checks, it is allowing children 12 and under and seniors to pass through the screening machines more than once if needed, rather than sending them immediately to secondary pat-down screening.

A pilot program being tested at four airports, including Portland, lets those 75 and older (about 3 percent of air travelers) keep on shoes and jackets as they walk through either the body scanners or metal detectors.

Carol Pucci: cpucci@seattletimes.com. On Twitter @carolpucci.