Seattle Approach control (S46) Concurrent Operations to Boeing Field (BFI) and Seattle-Tacoma International airport (SEA)

Background: The purpose of this Notice is to inform pilots landing/departing from either Boeing King County International Airport (BFI) or Seattle-Tacoma International Airport (SEA) under Instrument Flight Rules concerning the special use of visual separation to maintain efficiency at both airports.

Sequencing aircraft simultaneously to BFI and SEA under Instrument Flight Rules requires lateral and or vertical separation between aircraft while ensuring protected airspace for potential missed approaches. These requirements directly affect the capacity of both airports.

In a south flow, the ILS approach to BFI Runway 13R converges with the ILS approaches to SEA Runways 16 L/C/R directly over BFI. In a north flow, the departure paths for aircraft departing north from SEA Runways 34L/R and BFI Runway 31L diverge directly over the north end of BFI Runway 31L. BFI field elevation is 21 feet MSL and SEA field elevation is 433 feet MSL. BFI is located 4.5 NM north of SEA. The convergence and divergence of flight paths, differences in field elevations and distance between airports has made it possible to utilize visual separation under certain weather conditions to reduce the spacing normally provided to aircraft landing and departing SEA and BFI.

INFORMATION: When weather/operational conditions permit, BFI Tower controllers will provide visual separation during the following operations:

IFR arrivals to BFI Runways 13R/L and SEA arrivals Runways 16L/C/R

IFR arrivals from BFI Runways 13R/L and IFR departures from SEA Runways 34L/C/R

IFR departures from BFI Runways 31L/R and IFR departures from SEA Runways 34L/C/R

IFR arrivals to SEA 16R/C/L and IFR departures from BFI Runways 31L/R

IFR arrivals to BFI Runways 31L/R and IFR arrivals to SEA Runways 16L/C/R

When weather/operational conditions permit, SEA Tower controllers will provide visual separation during the following operations:

IFR arrivals to BFI Runways 31L/R and IFR departures from SEA Runways 34L/C/R

IFR arrivals to BFI Runways 31L/R and IFR arrivals to SEA Runways 16L/C/R

These procedures have proven to provide an equivalent level of safety compared to standard visual separation rules. This special use of visual separation procedures enables both airports to operate at or near capacity during periods of heavy demand.

If you have any questions or concerns, please contact the manager or designee of one the facilities listed below during normal business hours.

Seattle Approach Control - 206-214-4600

Seattle Air Traffic Control Tower - 206-214-2500

Boeing Field Air Traffic Control Tower - 206-658-6400

SEATAC (SEA) - Boeing Field (BFI) North Flow

Diagram depicting the north flow.

SEATAC (SEA) - Boeing Field (BFI) South Flow

Diagram depicting the south flow.