TagFour Post Plan(22)

Resolution A-93-03 adopted by the Puget Sound Regional Council General Assembly on April 29, 1993, amending the 1988 Interim Regional Airport System Plan (RASP) for long-term commercial air transportation capacity needs of the central Puget Sound region (King, Kitsap, Pierce, Snohomish counties). Establishes as preferred alternative a major supplemental airport in the four-county area plus

A 1993 confidential legal memorandum from law firm Cutler & Stanfield to the Airport Communities Coalition (ACC) outlines strategies for opposing the planned third runway expansion at Seattle-Tacoma International Airport. The memo recommends that the ACC Cities prioritize preventing new runway construction as their primary goal, with secondary goals focused on reducing noise impacts, limiting night flights, and improving mitigation for affected residents. The overarching strategy was to build enough political and legal leverage so that airport expansion decisions could not practically move forward without the ACC Cities' participation.

In 1992, the Ninth Circuit Court of Appeals upheld the FAA's decision to change flight patterns for turbine-powered aircraft at Seattle-Tacoma International Airport without preparing a full Environmental Impact Statement. The FAA had issued a Finding of No Significant Impact based on a computer noise model using the 65 decibel day-night sound level as the threshold for significant noise impact, which the court found to be a reasonable approach. The Seattle Community Council Federation had challenged the decision, arguing that the FAA failed to adequately assess the noise effects on surrounding communities.

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.

On April 2, 1990, the FAA announced it would implement the 'Four-Post Plan,' a set of air traffic control procedural changes at Seattle-Tacoma International Airport designed to reduce congestion, improve efficiency, and address worsening arrival delays. The plan, developed after nearly a year of public meetings, environmental review, and computer simulation of 13 alternatives, was determined to produce no significant noise impact on surrounding communities. The FAA cited a 30,000 increase in annual landings and takeoffs since 1988 and the failure of mediation talks to produce an agreed-upon flight path solution as key reasons for moving forward with the changes.

This 1990 document outlines a comprehensive package of noise abatement actions for Seattle-Tacoma International Airport, agreed upon by a Mediation Committee on March 31, 1990. It covers measures such as nighttime flight restrictions, soundproofing programs for nearby homes and public buildings, improved flight corridors, and a new noise management monitoring system. According to the technical consultant involved, full implementation of these agreements could reduce noise levels by approximately 50% for communities surrounding the airport.