TagNoise(310)

This 1990 FAA document explains why the Day Night Average Sound Level (DNL) was chosen as the standard metric for measuring airport noise. DNL averages noise exposure over a full 24-hour period, applying a penalty for nighttime flights, and has been adopted by multiple federal agencies—including the EPA, DOT, HUD, and DOD—as the most reliable way to assess how aircraft noise affects surrounding communities. The FAA formally incorporated DNL into federal regulation through FAR Part 150, Airport Noise Compatibility Planning, in 1981.

Resolution No. 3032, adopted by the Port of Seattle Commission on October 25, 1988, amends an earlier resolution (No. 3016) concerning noise management at Seattle-Tacoma International Airport. The key change gives the negotiating committee—known as the Joint Committee on Aircraft Overflights—the freedom to select their own neutral convener (mediator) from at least three interviewed candidates, rather than being restricted as under the previous rules. The chosen convener would be retained for up to four months to organize a mediation process, ensure all relevant parties are represented, and report regularly to the Port Commission on progress.

In July 1984, homeowners on 26th Ave. South near Seattle-Tacoma International Airport wrote to Port of Seattle Commissioners supporting the acquisition of their properties under the Noise Remedy program, citing increasing aircraft noise, growing industrial traffic hazards, and uncertainty that had delayed home maintenance. A separate letter from the Port's Director of Aviation to an airline captain acknowledged that non-compliance with existing noise abatement procedures — such as aircraft flying lower or turning sooner than prescribed — was a significant community concern, and noted that the Port was developing computer software using FAA radar data to automatically detect and report such violations.

In a June 22, 1984 letter to Seattle-Tacoma International Airport, United Airlines Vice President Captain M. E. Volz requested information about the airport's noise-sensitive areas and any formal or informal noise abatement procedures in place. The airline was conducting a survey of all airports it served in order to build a computer database of noise procedures accessible to pilots at any United Airlines terminal. United Airlines asked Sea-Tac to provide copies or descriptions of its noise procedures and to send future updates to the Flight Safety Department in Chicago.

In this February 28, 1984 letter, the FAA's Northwest Mountain Region reviewed the Port of Seattle's proposed Noise Remedy Program for Sea-Tac Airport, raising concerns about the criteria used to add 44 homes to an acquisition program and 275 homes to a purchase assurance program. The FAA questioned whether the new criteria of 'buffer for airport-related development' and 'neighborhood continuity' were sufficiently justified, particularly for homes along 24th Avenue South. The agency urged that all criteria be reasonable, clearly documented, and tied to measured noise impacts, and cautioned against finalizing the purchase assurance plan before key federal policy questions were resolved.

Minutes from the September 28, 1983 Policy Advisory Committee meeting at Sea-Tac Airport cover updates on noise reduction efforts, including new aircraft departure procedures, expanded noise monitoring stations, and a study on noise insulation and building codes. The committee also reviewed the 20-year Airport Master Plan, which will identify surplus Port-owned land that could be repurposed for commercial development or parks, and received updates on facilities improvements such as a new taxi holding area, completed runway safety zones, and the expanded South Satellite International Terminal.