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flight safetyFlight Corridor Safety Program

To help ensure safe aircraft takeoffs and landings, the Port of Seattle plans to remove obstructions, primarily trees, from around the runways at Sea-Tac Airport. Airports around the country periodically must remove obstructions as trees and vegetation mature. If not removed, these trees either are or soon will grow tall enough to encroach upon the airport’s airspace and pose a risk to aircraft safety and the safety of the surrounding community in the case of an aircraft emergency.

Project overview

The Port of Seattle has identified trees that need to be removed from the flight corridor. A vast majority of trees to be removed are located on property owned by either the Port of Seattle, Washington Department of Transportation or local city governments. Approximately 200 trees are located on residential or commercial property.

Flight Corridor Safety All activities related to removing and replanting trees will conform to applicable federal, state and local environmental review and permitting requirements. The Port of Seattle will conduct additional environmental review (i.e. SEPA), including public outreach and a comment period, for the remainder of the program. You can email questions about the flight corridor safety program to our dedicated project account:



Airport Community ​Ecology Fund
The Airport Community Ecology (ACE) Fund, authorized by the Port of Seattle Commission in November 2016, recognizes that neighboring communities that experience more impacts from airport operations should also experience more benefits. The Commission directed that the program support environmental projects and programs in the cities of SeaTac, Burien and Des Moines. Visit the ACE Fund site to learn more about the program.


Frequently Asked Questions (FAQ) 

Why is the Port of Seattle removing trees around Sea-Tac Airport?
Removal of the trees will ensure Sea-Tac Airport complies with all Federal Aviation Administration (FAA) regulations protecting the takeoff and landing corridors off the airport runways.These trees, which pose a risk to aircraft safety, are either penetrating the airport’s airspace or soon will grow tall enough to penetrate the airport’s airspace.
What is the plan for property owners who have trees on their property?
The Port will contact each property owner directly to notify them of the tree or trees on their property that need to be removed. Property owners will be offered a number of alternatives.
When will the trees be removed and replanted?
Trees on property owned by the Port of Seattle and local governments will be removed and replanted in 2017. Trees on residential and commercial property will be removed in 2018.

Environmental best management practices are part of the program’s overall design. Each area where trees are to be removed will be assessed to ensure that an individualized removal and replanting plan is carefully executed, consistent with the environmental characteristics specific to each location.
Where will the trees be replanted?
Every effort will be made to replant trees at the same location or in adjacent properties. Where it isn’t feasible to replant in the same area, the Port will work with local jurisdictions to arrive at a opportune location.
How many trees will be replanted?
The Port’s implementation plan proposed a minimum of 1 to 1 replacement ratio in non-critical areas and a 2 to 1 tree replacement ratio in critical areas. In addition to the minimum tree replacement requirement, the Port established a site revegetation objective to restore native forest or shrub communities.
What kind of trees will be replanted?
Native, low-height species will be planted on Port-owned properties such as Shore Pine, Oregon Ash and Red Alder. Local government and residential and commercial property owners will also have the option to select ornamental, non-native trees  for replanting.
What other steps will be taken to maintain the ecological and wildlife habitat at the impacted areas?
Key steps for minimizing impact include developing site-specific removal and revegetation plans. Those plans vary, but can include recommended steps such as performing manual tree removal within critical areas, protecting existing native shrubs and groundcovers and leaving stumps and roots in place on steep slopes.
For areas where trees provide visual buffer, what steps will be taken to maintain that barrier?
A buffer will be maintained between any residential properties that border tree-removal areas.
Did the program go through an environmental review?
The Port of Seattle, as lead agency, issued a Mitigated Determination of Non-Significance (MDNS) for the initial phase of the project (i.e. trees on Port-owned property) on August 26, 2016. This is allowed under Washington Administrative Code (WAC).  The Port of Seattle will conduct environmental review (i.e. SEPA) for the remainder of the program. This includes obstructions on commercial properties, public properties, and private properties located in the cities of SeaTac, Des Moines, and Burien.  Once this process begins, it will be known what type of environmental review is conducted, ex. Determination of Non-Significance (DNS) or Determination of Significance (DS) that could trigger a Mitigated Determination of Non-Significance (MDNS) or Environmental Impact Statement.

Additional SEPA review will be required for phases two and three and will include public outreach and comment periods.
Can you top the trees rather than remove them?
Topping a tree can often end up killing the tree and potentially creating a hazard. The airport’s Wildlife Hazard Management Plan prohibits tree topping adjacent to the airport because it provides an ideal roosting and nesting site for large birds. Many bird species pose a serious risk to aircraft safety and so, it’s important the airport take every effort to deter birds from making their homes close to the airfield.

Download the following to learn more:
Tree Topping: A Practice to Avoid, a Washington State University Extension fact sheet
Can you slow down this work and remove fewer trees each year?
The goal is to return the impacted areas to a natural state as quickly as is possible. If the program was extended and many of the same impacted areas disrupted by heavy equipment year after year, it would take longer for those areas to return to a natural state. So, the sooner the program starts and ends, the sooner the impacted areas can begin reestablishing themselves.
How does the program impact carbon capture in the region?
Through  revegetation efforts, the Port expects  carbon storage removed will be replaced, and likely exceeded, as replanted trees and vegetation continue to mature.