A cyberattack hit systems at Seattle-Tacoma International Airport over the weekend, causing headaches for airline staff and long lines for travelers.

As of Tuesday – just days ahead of one of the busiest travel weekends of the year – airport systems were still down with no clear timeline as to when outages would be resolved.

Airport officials aren’t sharing much about what happened as the incident is still under investigation, but spokesperson Perry Cooper said Monday the outage occurred after “nefarious characters” were seen on the airport’s computer system early Saturday, prompting officials to turn off the entire system.

Cooper said the airport is working with federal agencies to investigate the cause of the incident and would not comment on possible motives behind a cyberattack.

This has resulted in the movement of luggage through the airport getting badly snarled and long lines at some ticket counters, among other issues. Here’s what travelers should expect if they are flying through Sea-Tac in the next few days.

What systems are affected?

As of Tuesday, the airport’s website and app, ticketing computers for smaller and international airlines, and baggage sorting are all still experiencing outages.

Wi-Fi and phone systems inside the airport, departure and arrival boards, and the airport’s lost-and-found tracking system are also down.

Computers at “common use” check-in counters, or ticketing desks that are shared by multiple airlines, are off. Frontier, Spirit, Sun Country and all international airlines are among those especially affected because they do not have their own dedicated system within the airport, Cooper said.

The airport’s largest airlines, like Delta or Alaska, have not been affected because they have their own computer system, he said.

Those airlines with computer outages have begun handwriting boarding passes and bag tags for passengers who check in in person.

Because computers that operate the airport’s baggage check are down, airport and airline staff have had to manually sort bags to their proper gate and bag claims. This had led to some delays in both departing flights and bags arriving at their destination, Cooper said.

In a post on Tuesday, the airport said it was making progress in restoring elements of its baggage system and that staff is using “a variety of methods to ensure bags reach their aircraft.”

Security lines?

No, lines through security checkpoints have remained at normal levels.

The Transportation Security Administration’s systems at airports across the country are on their own secure system, which has not been affected by this outage, said Greg Hawko, TSA’s federal security director in Washington.

He encouraged everyone traveling, especially those who may choose to carry on a bag instead of checking it, to remember TSA’s rules for what to pack.

What can travelers do?

Mostly, travelers can expect long lines at ticket counters and possible delays in flights as staff work to ensure everyone and their bags make it onto their planes.

Lines through security checkpoints have remained smooth, Cooper said, and most of the wait is concentrated at the check-in area.

He encouraged travelers to avoid visiting a ticket counter, if possible. That means downloading a mobile boarding pass through an airline app or printing a physical ticket at home and leaving their checked bags at home.

“If you can travel without bags, just carry ons, please do so at this point,” he said.

If a traveler does need to visit a ticket counter, they should plan for extra time. Those traveling on affected airlines should arrive at least three hours early, Cooper said. Those who are traveling internationally and are planning to check a bag should give themselves as much time as possible, he added.

Cruise ships

The Port of Seattle’s maritime phone systems and website are out, but cruise ship operations are continuing as normal, Cooper said.

More info

While airport systems remain out, those looking for updated flight and gate information should check individual airline mobile apps or websites.

The airport is also posting updates on the Washington Ports website and its YouTube channel periodically.

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