SEAAirport Guide

How long a connection to book at Seattle airport

Allow at least three hours after an international arrival at SEA. See the security and train moves your connection needs.

The long glass-sided moving walkway corridor at Seattle-Tacoma airport.
Moving walkway, SEA

Book at least three hours between flights if you’ll clear U.S. entry at SEA. The Port of Seattle’s connections guidance gives 120 to 180 minutes. Three hours is the longer end of that range. For a domestic arrival, check where your next gate is and how much time remains before boarding ends.

The airport has one main terminal. You can walk between Concourses A, B, C and D after security. You’ll need the SEA Underground train for the separate N and S concourses. The Port says the Underground gets you where you’re going in two to five minutes, and the walks to and from the stations come on top of that. Check your airline’s SEA information for the minimum it will sell or accept for your flights, and its boarding cutoff.

Your arrival and next flight What to allow for
Domestic arrival, onward flight from A, B, C or D Walk between concourses without leaving the secure area.
Domestic arrival, onward international flight Follow the route to the departure gate, including the train if it is in N or S. Ask your airline whether your bag is checked through.
International arrival that needs U.S. entry processing Claim checked bags, clear Customs and Border Protection, recheck bags if connecting, and screen again.
Arrival from a U.S. preclearance airport These arrivals have already cleared passport control and skip the International Arrivals Facility.

If your connection takes you out of the secure area, allow time to clear TSA again and reach your next gate. Check the live checkpoint wait times before choosing a line.

If both flights are domestic

Find the route between your gates

If both gates are in A, B, C or D, follow the signs and stay after security. You don’t need a train simply because the gate letter changes among those four concourses.

For an S gate, follow signs to the Blue Line. A Station is across from A3, and B Station is below B20 and B21. Both are after security and connect to S Station. For an N gate, use the Green Line. C Station is by C11, and D Station is across from D2. Both are after security and connect to N Station.

The SEA Underground platforms at the Main Terminal stations and at N and S Stations are on Level 2. Follow the train signs down from the concourse rather than looking for a platform beside the gates.

Going between N and S takes another change: use the Green Line to D Station, the Yellow Line to A Station, then the Blue Line to S Station, or reverse that route. If a train is out of service, the Port of Seattle describes bus access to the satellite concourses. Follow the airport’s signs and ask staff for the active route rather than counting on the usual train pattern.

The Port of Seattle’s map places B20 and B21 at the end of B, and the D Annex gates D21 through D26 across from D5. At D21 through D26, you walk through the gate door and take a shuttle to the aircraft parked away from the terminal. Leave time for that last ride.

Arriving from abroad takes a different route

If your flight is arriving from outside the U.S. from an airport without preclearance, follow International Arrivals. SEA uses a bags-first process: collect all checked luggage before U.S. Customs and Border Protection, even when you have an onward flight. After clearance, stay to the right for airline bag recheck. Depending on the airline, you may instead need to exit and check the bag on the ticketing level. The Port of Seattle says entry processing can take 60 minutes or longer during holidays and the summer travel season, or when several international flights arrive together.

Flights from U.S. preclearance airports have already cleared passport control before departure, so they skip the International Arrivals Facility. Preclearance airports are Dublin and Shannon in Ireland, Aruba, Bermuda, Abu Dhabi, Nassau in the Bahamas, and Calgary, Toronto, Edmonton, Halifax, Montreal, Ottawa, Vancouver and Winnipeg in Canada. If you do need passport control at SEA, Global Entry is available for international arrivals.

Every connecting passenger on this arrival route must pass TSA screening again. The International Arrivals Facility transfer checkpoint is open from 6 a.m. to 9:45 p.m. Pacific and exits into Concourse A. It does not offer TSA PreCheck. When it is closed, exit to the pre-security side and use a main terminal checkpoint. Checkpoint 4 is open 24 hours before security in the Main Terminal. It’s closest to the Central Terminal and B and C gates, and it gives access to every gate. You may also need a main checkpoint if your airline sends you to the ticketing level to recheck a bag.

If you need TSA PreCheck after leaving the secure area, Checkpoint 1 on the baggage claim level is listed from 4 a.m. to 8 p.m. The airport’s checkpoint directory lists PreCheck there, though its live wait-times page lists general and CLEAR+ lanes. Checkpoint 2 is listed from 4 a.m. to 4 p.m. Checkpoint 3 stays open until 11:30 p.m., but its PreCheck lane runs 4 a.m. to 8 p.m. Checkpoints 1, 2 and 3 are closest to A and S gates. Checkpoint 5, closest to C, D and N, is open from 4 a.m. to 8 p.m. and lists TSA PreCheck. Checkpoint 6 is open 4 a.m. to 10 p.m., with PreCheck listed from 6 a.m. to 8 p.m. It is also closest to C, D and N. All main terminal checkpoints are before security and can get you to any gate.

Don’t treat a short international connection as a domestic transfer because the onward gate looks close.

When your connection starts to slip

If an international arrival leaves you short of time, the Port of Seattle says Alaska and Delta agents can help with bag recheck or rebooking. Staffing varies by demand. On separate tickets, ask each airline whether your bag needs a ticketing-level recheck and what happens if you miss the next flight.

If the walk or train change between gates is difficult, ask your airline for free wheelchair assistance between gates. Arrange it with the airline before travel. Our mobility guide explains how to arrange it.

More on our flights page.

Sources