DH8A crew had TCASII RA in S46 class B airspace.

Attributes
ACN	489630
Time
Date	200010
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : sea.vortac
State Reference	WA
Altitude	msl single value : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : s46.tracon
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 34l other vortac
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : s46.tracon
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 34l other
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp pilot : instrument
Experience	flight time last 90 days : 100 flight time total : 4200 flight time type : 1900
ASRS Report	489630
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	other
Miss Distance	horizontal : 2000 vertical : 1000
Supplementary
Problem Areas	Airspace Structure Flight Crew Human Performance ATC Human Performance
Primary Problem	Ambiguous

Narrative:

I was cleared for a visual approach to runway 34L at sea airport to maintain visual separation with a B757 landing on runway 34R sea. As we turned final runway 34L, 1 TA followed by an RA (monitor vertical speed). The B757 was in visual contact at all times. To avoid more RA's, TCASII was selected to TA only. I received no more TA's. My airplane was configured with gear and flaps down on GS and on centerline of extended runway 34L and localizer of runway 34L sea. The B757 was in visual contact all the way to our full stop on runway 34L sea.

Original NASA ASRS Text

Title: DH8A CREW HAD TCASII RA IN S46 CLASS B AIRSPACE.

Narrative: I WAS CLRED FOR A VISUAL APCH TO RWY 34L AT SEA ARPT TO MAINTAIN VISUAL SEPARATION WITH A B757 LNDG ON RWY 34R SEA. AS WE TURNED FINAL RWY 34L, 1 TA FOLLOWED BY AN RA (MONITOR VERT SPD). THE B757 WAS IN VISUAL CONTACT AT ALL TIMES. TO AVOID MORE RA'S, TCASII WAS SELECTED TO TA ONLY. I RECEIVED NO MORE TA'S. MY AIRPLANE WAS CONFIGURED WITH GEAR AND FLAPS DOWN ON GS AND ON CTRLINE OF EXTENDED RWY 34L AND LOC OF RWY 34L SEA. THE B757 WAS IN VISUAL CONTACT ALL THE WAY TO OUR FULL STOP ON RWY 34L SEA.

Data retrieved from NASA's ASRS site as of July 2007 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.