The Federal Aviation Administration (FAA) uses multiple tools for managing the safety and efficiency of the National Airspace System (NAS). One tool that Air Traffic Control (ATC) uses is to assign headings to departing aircraft as the Seattle-Tacoma International Airport (SEA). The SEA airport has seen a of 23% increase in aircraft operations between 2014 and 2016. Currently (2018), SEA airport is experiencing an additional 3.49% annual increase in aircraft operations, and S46 is experiencing a 6.10% annual increase over the same period in 2017, with more airlines and enhanced schedules occurring daily. To balance demand and increase efficiency and safety, Air Traffic Control (ATC) currently requests that slower moving departing turboprop aircraft be turned out of way of the faster moving, higher performing jet departures. When the airport is operating in north-flow, this means that southbound departing turboprops are manually assigned a westerly turned by the Seattle Terminal Radar Approach Control after takeoff. The FAA proposes to automate this manual request, which would improve safety and efficiency by eliminating the need for SEA ATC to coordinate with Seattle Terminal Radar Approach Control. FAA has undertaken an environmental review under the National Environmental Policy Act (NEPA) to assess the environmental consequences of that proposal.

Based on this NEPA analysis, FAA has concluded that the Preferred Alternative, which will automate a 250° westerly turn for southbound turboprops when Seattle-Tacoma International Airport is Operation in North-flow between the hours of 6 am and 10 pm, meets the need to address this safety and efficiency issue and will not have individual or cumulative impacts on the human environment.

The FAA has prepared a limited update to the Categorical Exclusion (CATEX) it issued in April 2018 for an automated 250-degree turn for turboprop aircraft that depart from Seattle-Tacoma International Airport (Sea-Tac) to the north. The update is in response to an order from the U.S. Court of Appeals, Ninth Circuit, pertaining to a legal challenge of the April 2018 CATEX. In response to the order, the FAA reexamined whether the turn could have a cumulative environmental impact when considered in connection with other planned projects, on and off airport. After reviewing information that is currently available about reasonably foreseeable projects, the FAA determined the turn would not have a significant cumulative environmental impact.

Supplemental Materials

• Limited Update to the Burien Categorical Exclusion (PDF)
• Burien Categorical Exclusion (PDF)
• Appendix A – Initial Environmental Review (PDF)
• Appendix B – Zoning for Burien Seattle Normandy Park (PDF)
• Appendix C – Correspondence with WA State Historic Preservation
  Officer (PDF)
• Appendix D – Public Comments and Responses (PDF)
• Appendix D – Public Comments, Errata (PDF)
• Appendix E – Endangered Species Act Listed Species (PDF)
• Preliminary Environmental Analysis (PDF)