Narrative:

Approaching jaksn intersection with a crossing restriction of 12000 ft; we were issued a revised restriction of 10000 ft; due to an ATC restriction. Descending to meet the restriction ATC issued a traffic alert. Two VFR light jet targets were noted and visually identified as we were responding to a TCAS RA. I climbed in response to the RA to approximately 15900 and turned off course approximately 60 degrees away from the intruding aircraft. They passed within 300 feet of our aircraft. The two targets appeared to be traveling with each other within close proximity of each other. Clear of the conflict ATC cleared us direct to hethr intersection to resume the arrival. Remainder of the flight was without incident. During the escape maneuver while turning; ATC also requested a turn of 20 degrees. I suspect the two intruders were either part of a special event practice or maneuvering clear of the practice area over lake washington.

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Original NASA ASRS Text

Title: AN A320 DESCENDING INTO SEA ON THE GLASR ARRIVAL TOOK EVASIVE ACTION IN RESPONSE TO A TCAS RA ON A FLIGHT OF TWO SMALL JETS.

Narrative: APPROACHING JAKSN INTERSECTION WITH A CROSSING RESTRICTION OF 12000 FT; WE WERE ISSUED A REVISED RESTRICTION OF 10000 FT; DUE TO AN ATC RESTRICTION. DESCENDING TO MEET THE RESTRICTION ATC ISSUED A TRAFFIC ALERT. TWO VFR LIGHT JET TARGETS WERE NOTED AND VISUALLY IDENTIFIED AS WE WERE RESPONDING TO A TCAS RA. I CLIMBED IN RESPONSE TO THE RA TO APPROXIMATELY 15900 AND TURNED OFF COURSE APPROXIMATELY 60 DEGREES AWAY FROM THE INTRUDING AIRCRAFT. THEY PASSED WITHIN 300 FEET OF OUR AIRCRAFT. THE TWO TARGETS APPEARED TO BE TRAVELING WITH EACH OTHER WITHIN CLOSE PROXIMITY OF EACH OTHER. CLEAR OF THE CONFLICT ATC CLEARED US DIRECT TO HETHR INTERSECTION TO RESUME THE ARRIVAL. REMAINDER OF THE FLIGHT WAS WITHOUT INCIDENT. DURING THE ESCAPE MANEUVER WHILE TURNING; ATC ALSO REQUESTED A TURN OF 20 DEGREES. I SUSPECT THE TWO INTRUDERS WERE EITHER PART OF A SPECIAL EVENT PRACTICE OR MANEUVERING CLEAR OF THE PRACTICE AREA OVER LAKE WASHINGTON.

Data retrieved from NASA's ASRS site as of January 2009 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.