Narrative:

[Aircraft] was being vectored for the ILS runway 14R into bfi. The aircraft was at 4000 feet south of ZZZ for a regional jet departing ZZZ southbound climbing to 3000 ft. Once that conflict was passed; [aircraft] was descended to 3000 ft. And issued traffic on a VFR target southbound at 2500 feet. Once past that traffic; [aircraft] was descended to 2200 ft. And turned left to a base heading of 220 degrees. Again; traffic was issued for the 2500 feet target and they got that traffic in sight. Additionally; traffic was issued for another target northwest-bound at 1700 feet. As [aircraft] was turning to join the localizer from the southwest; the 1700 feet target started to climb into the [medium transport aircraft]. Traffic was again issued and [aircraft] responded to a TCAS RA and descended. As [aircraft] was climbing back up to 2200 feet; the previous 2500 feet target started a turn towards bfi on the localizer; descending. [Aircraft] lost sight of that traffic and was given an altitude of 2100 feet and turned to the southwest to avoid the descending VFR target. [Aircraft] responded to a second RA for that target. [Aircraft] advised with bfi in sight and was cleared for the visual approach. The bfi final must be protected or there will be an accident at some point. There needs to be airspace underneath the ZZZ bravo that is sterile so jets going 200 knots can safely arrive at bfi. Until this happens; there will continue to be near misses into bfi.

Related reports:

Google
 

Original NASA ASRS Text

Title: Approach Controller reported vectoring an aircraft on an ILS Approach to avoid two separate unidentified VFR aircraft not in communication with ATC.

Narrative: [Aircraft] was being vectored for the ILS Runway 14R into BFI. The aircraft was at 4000 feet south of ZZZ for a regional jet departing ZZZ southbound climbing to 3000 ft. Once that conflict was passed; [aircraft] was descended to 3000 ft. and issued traffic on a VFR target southbound at 2500 feet. Once past that traffic; [aircraft] was descended to 2200 ft. and turned left to a base heading of 220 degrees. Again; traffic was issued for the 2500 feet target and they got that traffic in sight. Additionally; traffic was issued for another target northwest-bound at 1700 feet. As [aircraft] was turning to join the localizer from the southwest; the 1700 feet target started to climb into the [Medium Transport Aircraft]. Traffic was again issued and [aircraft] responded to a TCAS RA and descended. As [aircraft] was climbing back up to 2200 feet; the previous 2500 feet target started a turn towards BFI on the localizer; descending. [Aircraft] lost sight of that traffic and was given an altitude of 2100 feet and turned to the southwest to avoid the descending VFR target. [Aircraft] responded to a second RA for that target. [Aircraft] advised with BFI in sight and was cleared for the visual approach. The BFI final must be protected or there will be an accident at some point. There needs to be airspace underneath the ZZZ Bravo that is sterile so jets going 200 knots can safely arrive at BFI. Until this happens; there will continue to be near misses into BFI.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.