S46 TRACON controller reported an aircraft departed an airport IFR and was immediately in conflict w...

Narrative:

Aircraft X departed kbfi IFR. As soon as the aircraft checked on frequency I had to issue a traffic alert for two VFR aircraft in the vicinity of aircraft X and the aircraft subsequently reported responding to a TCAS-RA. Although the pilot did not indicate what action the RA advised; the aircraft appeared to continue the climb that I initially issued. I do not know if tower issued any traffic to aircraft X during his departure prior to transferring communications to me. Aircraft X subsequently advised the RA complete and continued on without further incident.this is another report of a continued problem within our airspace. Something needs to change. The VFR aircraft are transiting a very narrow; busy corridor of airspace and are doing so without any communication with ATC. It is simply unsafe. The VFR aircraft in this area at the very least need to be in communication with ATC so that we can assign; as necessary; altitude restrictions ensuring the safety of all the aircraft involved. The solutions are not hard and while they are potentially more restrictive to VFR aircraft the bottom line is that what happens day in and day out in that airspace as it exists and operates now will eventually result in a very bad accident.

Original NASA ASRS Text

Title: S46 TRACON Controller reported an aircraft departed an airport IFR and was immediately in conflict with two VFR aircraft not in communication with ATC. The departing IFR aircraft responded to an RA.

Narrative: Aircraft X departed KBFI IFR. As soon as the aircraft checked on frequency I had to issue a traffic alert for two VFR aircraft in the vicinity of Aircraft X and the aircraft subsequently reported responding to a TCAS-RA. Although the pilot did not indicate what action the RA advised; the aircraft appeared to continue the climb that I initially issued. I do not know if Tower issued any traffic to Aircraft X during his departure prior to transferring communications to me. Aircraft X subsequently advised the RA complete and continued on without further incident.This is another report of a continued problem within our airspace. Something needs to change. The VFR aircraft are transiting a very narrow; busy corridor of airspace and are doing so without any communication with ATC. It is simply unsafe. The VFR aircraft in this area at the very least need to be in communication with ATC so that we can assign; as necessary; altitude restrictions ensuring the safety of all the aircraft involved. The solutions are not hard and while they are potentially more restrictive to VFR aircraft the bottom line is that what happens day in and day out in that airspace as it exists and operates now will eventually result in a very bad accident.

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.

Attributes
ACN	1334488
Time
Date	201602
Local Time Of Day	1801-2400
Place
Locale Reference	S46.TRACON
State Reference	WA
Aircraft 1
Make Model Name	Falcon 7X
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Route In Use	Vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Plan	VFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 1.2
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict

S46 TRACON controller reported an aircraft departed an airport IFR and was immediately in conflict with two VFR aircraft not in communication with ATC. The departing IFR aircraft responded to an RA.