TagVashon Island Fair Skies(4)

Written comments submitted by Vashon Island Fair Skies to the FAA regarding noise policy review, focusing on ambient noise considerations and challenges in modeling airframe noise generation for aircraft arrivals. The document criticizes the current DNL metric and discusses technical issues with Sound Exposure Level calculations and airframe noise modeling.

Dear Councilmember Kwon & SeaTac City Council, We’re requesting the help of the City of SeaTac to lobby the Port of Seattle to make a procedural change in how the data from their system of 24 Port owned Larson Davis 831 noise monitors is collected and retained. Our 501(c)3 Vashon Island Fair Skies is located, not surprisingly, on Vashon Island and as such has no city government to lobby on our behalf. Currently the Port does not retain the raw second by second measured sound level data but instead contracts the data collection and analysis to the vendor L3Harris. The vendor periodically downloads this data and then purges it from the monitors. They use this data to build a list of SELs (Sound Exposure Level) for overflight events at that monitor location along with a set of noise statistics for the site. Nothing precludes the Port from also downloading a copy of their own raw second by second data from the Port owned noise monitors before L3Harris purges it. Alternatively, if the Port’s Noise Office wants to retain a completely hands-off relationship with their own noise monitors, the vendor L3Harris could deliver the raw data with the other processed data currently being supplied. This raw data amounts to ~62 MB/month (~40 MB compressed) per monitor, which is tiny by today’s standards. At the UC Davis Aviation Noise & Emissions Symposium in March I spoke with L3Harris, who was a sponsoring vendor and had a booth there. Samuel Carter, their Training…

A color-coded map showing complaint data by ZIP code in the SeaTac area for August 2019. The map displays different complaint volume ranges from 1-51 complaints (green) to over 13,000 complaints (red), with ZIP code 98070 showing the highest complaint levels in red.

A petition to the Port of Seattle Commission requesting the addition of two noise monitors on Vashon Island to monitor aircraft noise from new FAA NextGen flight procedures. The petition cites concerns about focused flight paths over Vashon Island at low altitudes affecting approximately 250 arrivals per day in Southflow operations.