Washington Aviation System Plan, Chapter 9: Alternate Airports Assessment

A 2009 Washington State aviation planning study assessed which existing airports could absorb overflow demand from airports projected to hit capacity limits by 2030, with Sea-Tac International among those forecast to exceed both airfield operations and passenger terminal capacity. The analysis evaluated potential alternate airports within roughly 60 miles of Sea-Tac based on factors such as available capacity, runway length, and highway access, while noting that free-market decisions by airlines and passengers would ultimately determine how traffic is distributed. The study was intended as a first-level screening, with more detailed environmental and operational analyses expected before any formal relief airport designations could be made.

Notes

Chapter 9 of the Washington Aviation System Plan (WASP), dated July 1, 2009, assessing alternate airports to relieve capacity-constrained airports across Washington State by 2030. Twenty-four airports are forecast to approach or exceed 100% capacity in airfield operations, passenger terminal, aircraft storage, or air cargo by 2030. Seven airports forecast to exceed airfield and/or passenger terminal capacity include Boeing Field, Sea-Tac International, Kenmore Air Harbor, Harvey Field, Tri-Cities, Anacortes, and Orcas Island. Seventeen airports forecast to exceed aircraft storage capacity only include Felts Field, Crest Airpark, Pearson Field, Renton Municipal, Pullman/Moscow Regional, and others. Screening factors for alternate airports include proximity (30-45 miles for general aviation, 60 miles for commercial airports such as Sea-Tac), available capacity, runway length, and ground access. Analysis conducted under LATS Phase II by WSDOT for the Aviation Planning Council.

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