Light Transport
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 1
Situational Awareness; Communication Breakdown; Workload
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Staffing; Human Factors; Procedure
I was working arrival east and BFI arrival combined with a good amount of BFI traffic inbound. I was getting BFI arrivals from all 4 corners into my airspace and trying to sequence while also trying to feed the SEA final. Aircraft X was vectored to final behind Aircraft Y. I did not see that Aircraft Y was an F-Category aircraft before I switched Aircraft X to BFI Tower. Upon realization that I needed 4.0 miles for wake turbulence; I tried to contact BFI Tower to see if they could slow Aircraft X but nobody answered. Aircraft Y started slowing and compression caused Aircraft X to get within 4 miles of the aircraft in front.[Sector] should have been split with the amount of BFI arrivals inbound. My guess is that; like always; staffing forced the situation to remain combined causing the loss. I also have no idea why BFI Tower let Aircraft X continue the approach after they saw that wake turbulence separation was going to be lost unless they asked Aircraft X if they could provide visual with the aircraft in front.
S46 TRACON Controller reported a loss of separation on final due to not realizing an aircraft involved was a Category F.