
COMMISSION AGENDA – Briefing Item No. 11a Page 3 of 5
Meeting Date: March 28, 2023
Template revised September 22, 2016.
The highlights in 2022 include:
(1) Ground Noise Study – The study, which analyzed airfield ground noise sources
and identified potential mitigation measures, was completed in the spring. Airfield ground noise
sources identified in the study by the consultants included stop and go aircraft queuing,
traditional takeoffs, reverse thrust, auxiliary power unit (APU) use, engine maintenance run-ups
and dual engine taxiing. The AN Working Group, since the study’s completion, has been
reviewing each of the potential mitigation measures to determine feasibility and if there’s
agreement, the steps to implementation.
(2) Discouraging Reverse Thrust – Identified as a noise source in the Ground Noise
Study, reverse thrust is used by pilots to deaccelerate aircraft upon landing. In coordination with
the FAA, Alaska Airlines, Delta Airlines and the members of the AN Working Group, updated
language was developed that discourages the use of reverse thrust at SEA at all times of the day
and beyond what is necessary. The updated, voluntary SEA language was implemented in
January 2023 and will be followed by an air carrier awareness campaign in mid-2023.
(3) Encouraging Rolling Takeoffs – Identified as a noise source in the Ground Noise
Study, rolling takeoffs have less of a noise footprint than traditional takeoffs that require aircraft
to power up after coming to a complete stop. Noise monitoring conducted by Port staff over the
summer to evaluate rolling takeoffs didn’t produce usable data. However, based upon past
results at a comparable airport, implementation of voluntary SEA language identifying rolling
takeoffs as having a noise benefit was pursued. In coordination with the FAA, Alaska Airlines,
Delta Airlines and the members of the AN Working Group, new, voluntary SEA language
promoting rolling takeoffs is in development. If enacted, the language will be followed by an air
carrier awareness campaign in 2023.
Aviation Near-term Noise Action Agenda – Earlier Achievements
(1) Late Night Noise Limitation Program – Voluntary measure to reduce late night
noise by incentivizing air carriers to fly at less noise sensitive hours or transition to quieter
aircraft. Program commenced in July 2019 with regular reporting each quarter to StART, air
carriers and other external audiences.
(2) Runway Use Plan – Informal Runway Use Plan, implemented in late 2019, to
minimize use of the Third Runway during the late-night hours (12:00 AM to 5:00 AM). Late night
operations on the Third Runway have dropped dramatically since implementation of the Runway
Use Plan.
(3) Glide Slope Adjustment – Raise Runway 34R’s glideslope to lessen aircraft
approach noise. Implementation is contingent on the Sustainable Airport Master Plan’s (SAMP)
finalization and FAA approval.
(4) Monthly Noise Comment Reporting – Provide up-to-date, accessible information
on noise complaints and comments submitted by the public. Online monthly reporting began
with June 2020.