Introduction

Seattle-Tacoma International Airport (KSEA) is an international airport serving the Seattle metropolitan area in the U.S. state of Washington. It is located between Seattle, the most populous city in the state, and Tacoma, the third-most populous city in the state. The airport is located in the city of SeaTac and managed by the Port of Seattle. It is the 37th busiest airport in the world by passenger traffic and the 12th busiest in the United States.

Air Traffic

SeaTac has three parallel runways. Depending on wind direction, air traffic will flow either north or south. One runway is typically used for departures while the other two are used for arrivals but other times this may be reversed. In night hours, planes are more likely to arrive on a different runway. SeaTac is busy nearly the entire day, but busiest from around 6:00 am to 12:00 pm and quietest from 1:00 am to 4:00 am.

North Flow

SeaTac uses this pattern when winds are blowing from the north to the south. It is used about 35% of the time, most commonly in the summer months. Approaching planes approach from the south facing north. Departing planes depart headed north. 

• Arrivals most commonly use Runway 34L but larger planes might land on Runway 34C or 34R. 

• Departures most commonly use Runway 34R to take off.

South Flow

SeaTac uses this pattern when winds are blowing from the south to the north. It is used about 65% of the time, most commonly in the winter months. Approaching planes approach from the north facing south. Departing planes department headed south.

• Arrivals most commonly use Runway 16R but larger planes might land on Runway 16C or 16L.

• Departures most commonly use Runway 16L to take off.

Airlines

Alaska Airlines is headquartered at the airport but Delta Air Lines also has a hub at SeaTac. These two carriers make up around about 75% of traffic at the airport. Other domestic carriers include American Airlines, Frontier Airlines, Hawaiian Airlines, Southwest Airlines, Sun Country Airlines, and United Airlines.

Alaska, American, Delta, and United Airlines also use the regional carrier SkyWest Airlines, which primarily operates Embraer E175s.

Cargo airlines typically leave in the early morning.

Aircraft

Boeing 737 -- Very common at SeaTac, these make up over 40% of SeaTac traffic. Almost all of Alaska Airlines' fleet are 737-700s, 737-800s, 737-900ERs, and 737-9MAXs. Delta, United, and Southwest all use 737s as well. 

Boeing 747 -- No airline operates passenger 747s at SeaTac, but there are occasional 747 cargo planes from Asiana, Korean, Cargolux, and more.

Boeing 757 -- Flown primarily by Delta Airlines but also some freight carriers. Not the most common and not the most rare.

Boeing 767 -- Used by FedEx Cargo and ABX Air. 

Boeing 777 -- The largest passenger plane to see at SeaTac. International carriers that fly 777s to SeaTac include Asiana Airlines, Emirates, Philippine Airlines, and Qatar Airlines. The freight variant is used by China Cargo Airlines.

Boeing 787 -- A common sight among international carriers. International carriers that fly 787s to SeaTac include All Nippon Airways, British Airways, Eva Air, Japan Airlines, Korean Air, and Virgin Atlantic.

Airbus A320 -- Quite common at SeaTac. Flown by Delta, American, and United.

Airbus A330 -- Fairly common at SeaTac. Flown by Aer Lingus, Delta, Condor, and Hawaiian Airlines.

Airbus A340 -- Uncommon sight at SeaTac. Sometimes flown by Lufthansa when not using an A330. 

Airbus A350 -- A common sight among international carriers and long range Delta flights. International carriers that fly A350s to SeaTac include Air France, Philippine Airlines, Singapore Airlines, Starlux, and Turkish Airlines.

Airbus A380 -- Not present at SeaTac :(

Embraer E175 -- Very common, these make up about 30% of all traffic at SeaTac. Used by Horizon Airlines and SkyWest Airlines on behalf of Alaska, Delta, United, and American Airlines. SkyWest operates on behalf of all four while Horizon operates for Alaska only. Keep an eye out for Horizon, there are four special livery planes.

Bombardier CRJ-700 -- Uncommon sight at SeaTac. Most commonly flown by SkyWest on behalf of American Airlines (American Eagle brand) but occasionally in SkyWest's blue-and-white paint scheme. A few of these planes visit SeaTac a day.

DHC-8 400 -- Uncommon sight at SeaTac but they are present. Flown by only two airlines, Jazz Aviation on behalf of Air Canada, and WestJet Encore on behalf of WestJet. A few of these planes visit SeaTac a day.

More coming soon!