Sea-Tac Faces a Capacity Crunch It Can’t Outgrow

Article Summary:

The airport will fail to meet the Puget Sound region’s long-term demand for passenger air service, study concludes

Bill Conroy

The airport will fail to meet the Puget Sound region’s long-term demand for passenger air service, study concludes
The Puget Sound Regional Council (PSRC), a planning agency for the four-county Puget Sound region, has released some key initial findings from an ongoing regional aviation study showing Sea-Tac International Airport faces a severe capacity crunch that ill prevent it from meeting the area’s long-term commercial aviation demands.

The big takeaway from the just-released PSRC data: “Even with planned investments, Sea-Tac Airport will not be able to meet the region’s 2050 demand for passenger air service.”

In fact, the near-term projects planned as part of Sea-Tac’s Sustainable Airport Master Plan (SAMP) are projected to accommodate about 28 million passenger enplanements by 2027, well short of the anticipated demand of 31.1 million passenger enplanements for the Puget Sound region, according to the PSRC. Enplanements, or passengers boarding a plane to fly somewhere, represent roughly half of total passenger traffic at an airport, with the balance being passenger arrivals ― or deplanements.

Phase 1 of Sea-Tac’s SAMP is now under environmental review and calls for some 30 projects to be completed or under construction by 2027, including a new 19-gate airport terminal. The estimated price tag for those projects, according to Sea-Tac spokesperson Perry Cooper, is $4.5 billion. Another slate of Sea-Tac projects is expected to be identified in Phase 2 of the SAMP that will be designed to address longer-term airport capacity needs. Planning for Phase 2 is scheduled to begin after the completion of the PSRC aviation baseline study.

The initial data just released from the PSRC study shows that even with completion of those long-term SAMP projects ― which would increase total aircraft gates to 113, up from the current 83 ― Sea-Tac will fall short of meeting the region’s long-term demand for commercial passenger air service.

The capacity crunch at Sea-Tac, if left unaddressed, will translate into longer flight delays for passengers, according to the PSRC. The average annual aircraft delay is projected to jump from about 10 minutes at the 2018 level of 438,391 landings and takeoffs (called “operations”) to nearly 45 minutes once aircraft operations reach the 550,000 level annually. A Washington Aviation System Plan capacity study conducted in 2017 predicts Sea-Tac will exceed that mark by 2034.

Making matters worse, as congestion at Sea-Tac increases, propelled by the Puget Sound region’s population growth ― projected to reach 5.8 million by 2050, up from 4.1 million today ― drive-times to Sea-Tac will get “substantially worse for most of the region’s residents,” the PSRC assessment states.

In 2017, the drive to Sea-Tac for 38% of individuals in the four-county Puget Sound region was outside of an hour. By 2050, that figure is projected to increase to 58%, the PSRC projects.

State legislation enacted this past spring seeks to address Sea-Tac’s growing capacity woes by establishing a new state commission composed of representatives from government, business and the community appointed by the governor. The commission is charged with coming up with a short list of six preferred locations for developing a new airport outside King County by Jan. 1, 2021. That list must be narrowed down to a single preferred location by Jan. 1, 2022, the legislation states.