The three parallel runways run nearly north–south, west of the passenger terminal and are 8,500 to 11,900 feet (2,600–3,600 m) long.
In 2008 the airport averaged 946 aircraft operations per day, 89% being commercial flights, 10% air taxi operations and 1% transient general aviation.

A new control tower was built beginning in 2001 and opened November 2004, at a cost of $26 million.
The floor of the new tower's control cab is 233 ft (71 m) above ground level; the tower's overall height including antennas is 269 ft (82 m).
The cab has 850 sq ft (79 m²) of space and was designed to support operation by ten controllers, with possible future expansion up to 15.
The site and construction method of the tower were designed to maximize visibility and efficacy of radar systems.
The airport's original control tower, built in the 1950s, is now located in the airport's passenger terminal and used as a ramp control tower, after being repaired from damage caused by the Nisqually earthquake in 2001.

A recurring problem at the airport is misidentification of the westernmost taxiway, Taxiway Tango, as a runway.
A large "X" has been placed at the north end of the taxiway, but a number of aircraft have landed on the taxiway.
The FAA issued an alert notice dated from August 27, 2009, to September 24, 2009, urging airplanes about taking precautions such as REILs and other visual cues while landing from the north.

In 2007 the airport became the first airport to implement an avian radar system providing 24-hour monitoring of wildlife activity across the airfield.
This pilot program, designed and implemented with the assistance of the University of Illinois Center of Excellence for Airport Technology (CEAT), was designed to decrease potentially fatal incidents involving collisions with birds and to provide a test bed for implementation of the technology in the US which was expected to begin in 2009.
The technology is part of a strategy to reduce the presence of wildlife on the airfield.

The Seattle office of the National Weather Service operates a weather station at the airport, with a temperature gauge between the center and eastern runways.
The airport has served as Seattle's official weather recording location since 1945.
The three parallel runways run nearly north–south, west of the passenger terminal and are 8,500 to 11,900 feet (2,600–3,600 m) long. In 2008 the airport averaged 946 aircraft operations per day, 89% being commercial flights, 10% air taxi operations and 1% transient general aviation.
A new control tower was built beginning in 2001 and opened November 2004, at a cost of $26 million. The floor of the new tower's control cab is 233 ft (71 m) above ground level; the tower's overall height including antennas is 269 ft (82 m). The cab has 850 sq ft (79 m²) of space and was designed to support operation by ten controllers, with possible future expansion up to 15. The site and construction method of the tower were designed to maximize visibility and efficacy of radar systems. The airport's original control tower, built in the 1950s, is now located in the airport's passenger terminal and used as a ramp control tower, after being repaired from damage caused by the Nisqually earthquake in 2001.
A recurring problem at the airport is misidentification of the westernmost taxiway, Taxiway Tango, as a runway. A large "X" has been placed at the north end of the taxiway, but a number of aircraft have landed on the taxiway. The FAA issued an alert notice dated from August 27, 2009, to September 24, 2009, urging airplanes about taking precautions such as REILs and other visual cues while landing from the north.
In 2007 the airport became the first airport to implement an avian radar system providing 24-hour monitoring of wildlife activity across the airfield. This pilot program, designed and implemented with the assistance of the University of Illinois Center of Excellence for Airport Technology (CEAT), was designed to decrease potentially fatal incidents involving collisions with birds and to provide a test bed for implementation of the technology in the US which was expected to begin in 2009. The technology is part of a strategy to reduce the presence of wildlife on the airfield.
The Seattle office of the National Weather Service operates a weather station at the airport, with a temperature gauge between the center and eastern runways. The airport has served as Seattle's official weather recording location since 1945.
Seattle–Tacoma International Airport