Same runway assignment assumed. Near midair collision in multiple runway operation parallel runways.

Attributes
ACN	285352
Time
Date	199410
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sea
State Reference	WA
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sea tower : sea
Operator	common carrier : air carrier
Make Model Name	B747-100
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent : approach
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	approach : straight in approach : visual
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 240 flight time total : 20000
ASRS Report	285352
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : clearance non adherence : far other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 75 vertical : 400
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Pilot Deviation
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

We were flying a 747 from japan to sea and were entering elliott bay for a bay visual to runway 16R at sea. We were at 3000 ft with ceiling of about 3300 ft in our area. Sea approach told us that air carrier Y was 5 mi north of our position -- we only acknowledged 'roger' as we did not have the aircraft insight and it was not given to us as traffic. As we approached boeing field (5 mi north of sea) we were on the runway 16R GS and we suddenly noticed traffic on TCASII 800 ft below us. Our initial reaction was either a traffic aircraft or boeing traffic. However, the separation decreased to 700-600 ft and at that point we had a TCASII RA to 'stop descent.' I asked sea tower if they knew the aircraft was as we had had an RA. Sea said that it was air carrier Y on a visual to runway 16L. Separation got to 400 ft vertical during all of this and when I looked down out of my left side window all I could see was the left wing of the dash 8. At no time were we ever informed of an aircraft on approach to runway 16L which is a very close parallel runway. What happened staggered approachs with close runways? What happened to ATC notifying both aircraft if parallel visuals are going to be used? How can visual separation be maintained if 1 aircraft is allowed to pass another? What happened to wake turbulence. Caution and education? The ATC system needs to slow down and evaluate itself.

Original NASA ASRS Text

Title: SAME RWY ASSIGNMENT ASSUMED. NMAC IN MULTIPLE RWY OP PARALLEL RWYS.

Narrative: WE WERE FLYING A 747 FROM JAPAN TO SEA AND WERE ENTERING ELLIOTT BAY FOR A BAY VISUAL TO RWY 16R AT SEA. WE WERE AT 3000 FT WITH CEILING OF ABOUT 3300 FT IN OUR AREA. SEA APCH TOLD US THAT ACR Y WAS 5 MI N OF OUR POS -- WE ONLY ACKNOWLEDGED 'ROGER' AS WE DID NOT HAVE THE ACFT INSIGHT AND IT WAS NOT GIVEN TO US AS TFC. AS WE APCHED BOEING FIELD (5 MI N OF SEA) WE WERE ON THE RWY 16R GS AND WE SUDDENLY NOTICED TFC ON TCASII 800 FT BELOW US. OUR INITIAL REACTION WAS EITHER A TFC ACFT OR BOEING TFC. HOWEVER, THE SEPARATION DECREASED TO 700-600 FT AND AT THAT POINT WE HAD A TCASII RA TO 'STOP DSCNT.' I ASKED SEA TWR IF THEY KNEW THE ACFT WAS AS WE HAD HAD AN RA. SEA SAID THAT IT WAS ACR Y ON A VISUAL TO RWY 16L. SEPARATION GOT TO 400 FT VERT DURING ALL OF THIS AND WHEN I LOOKED DOWN OUT OF MY L SIDE WINDOW ALL I COULD SEE WAS THE L WING OF THE DASH 8. AT NO TIME WERE WE EVER INFORMED OF AN ACFT ON APCH TO RWY 16L WHICH IS A VERY CLOSE PARALLEL RWY. WHAT HAPPENED STAGGERED APCHS WITH CLOSE RWYS? WHAT HAPPENED TO ATC NOTIFYING BOTH ACFT IF PARALLEL VISUALS ARE GOING TO BE USED? HOW CAN VISUAL SEPARATION BE MAINTAINED IF 1 ACFT IS ALLOWED TO PASS ANOTHER? WHAT HAPPENED TO WAKE TURB. CAUTION AND EDUCATION? THE ATC SYS NEEDS TO SLOW DOWN AND EVALUATE ITSELF.

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.