TagSea-Tac Airport(2023)

In this 1992 letter, acoustics expert James D. Chalupník explains to attorney Richard Aramburu how aircraft noise near Seattle's Sea-Tac Airport is measured and rated, focusing on the appropriateness of the Ldn metric and the data used in the FAA's Integrated Noise Model (INM). He outlines the key physical properties of noise—intensity, frequency distribution, and fluctuation over time—and describes how various weighting schemes, particularly the A-weighting (dBA) scale, are used to approximate human perception of loudness and annoyance. The letter also notes the limitations of simpler metrics and introduces more sophisticated rating methods such as Stevens' Loudness Level and Perceived Noise Level for evaluating aircraft noise.

The CASE Group (Citizens' Alternatives to Sea-Tac Expansion) was formed in 1987 to oppose the Port of Seattle's plans to add a third runway at Sea-Tac Airport, gathering over 4,600 protest signatures and prompting the King County Council to pass a resolution against the expansion. The coalition organized public hearings, lobbied Port Commissioners, and circulated petitions urging state officials to reject expansion recommendations in favor of building a new regional airport away from densely populated areas. Their core argument was that alternatives to Sea-Tac expansion represented sounder economic and environmental choices for the Central and South Puget Sound region.

These two Port of Seattle Flight Track Sample maps compare jet aircraft arrival and departure patterns at Seattle-Tacoma International Airport (SEA) under south flow conditions, one from March 22, 1989 (pre-4 Post) and one from March 31, 1991 (4 Post). Both charts plot all jet flight tracks between approximately 4:30–24:00 and 6:00–22:00 respectively, showing how flight paths over the Seattle region shifted between the two periods. The maps are annotated to highlight southbound departures and arrivals over Seattle, serving as visual evidence for noise impact analysis related to airport runway and procedure policy changes.

The Seattle-Tacoma International Airport Noise Budget, effective January 1, 1991, is a formal agreement designed to limit and gradually reduce overall aircraft noise levels at Sea-Tac Airport. It establishes a system of noise allocations assigned to individual passenger and cargo carriers, measured through defined noise exposure levels, with limits enforced on both a quarterly and annual basis. The agreement outlines key definitions and rules governing how noise is measured, allocated, and managed, including provisions for new entrants, international carriers, and government aircraft.

In 1990, the Port of Seattle's Port Commission passed Resolution No. 3062, endorsing an agreement reached by the Seattle-Tacoma International Airport Noise Mediation Committee after 18 months of study by community representatives, airlines, pilots, the FAA, and airport users. The agreement established a Noise Budget and Nighttime Limitations program aimed at reducing aircraft noise levels by at least 50% by 2001 compared to a 1989 baseline, while also expanding the existing Noise Remedy Program to insulate more homes and remove financial burdens from homeowners. The resolution authorized the Executive Director to implement the agreement's terms, including revising airport regulations, entering noise limitation agreements with airline tenants, and installing a Noise Management System to monitor compliance.