Air carrier has near midair collision with another air carrier flight on visual approach. TCASII RA.

Attributes
ACN	199334
Time
Date	199201
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : sea
State Reference	WA
Altitude	msl bound lower : 800 msl bound upper : 1100
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : sea
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent : approach descent other
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Light Transport
Flight Phase	descent : approach descent other
Route In Use	approach : visual
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 25000 flight time type : 3000
ASRS Report	199334
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 300 vertical : 300
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

My flight was vectored by sea approach for a visual approach to runway 16L at sea. I was flying the aircraft. Approach asked if we had the airport in sight, which we did. They advised that an air carrier B flight was also on a visual to runway 16R and they had us in sight. We saw the air carrier B aircraft approaching from the right and high. Approach control also advised that an air ambulance was on final to runway 32 at boeing field. I had that aircraft in sight to the left and low. We were cleared for a visual approach to runway 16L and to cross boeing field at or above 2100. We crossed at 2100 ft. Between boeing field and seatac the air carrier B flight passed us on the approach. The air carrier B appeared to be drifting over to 16L and descending on top of us. Our TCASII went off and turned red with an RA to descend. The air carrier B altitude was 1100 according to the TCASII. I moved over to the left of the centerline of 16L and was approximately 800 AGL and looking up at the air carrier aircraft. The tower asked our altitude from an alerter going off in the tower. I told them about the air carrier B aircraft and that I had the ground and the field in sight. Had I started a go around I would have hit the air carrier B aircraft. The air carrier B said they were lined up with 16R. I slowed the aircraft to 138 KTS. Vref was 124 KTS. I let the air carrier B get further ahead of us and continued the approach to 16L and made a safe successful landing on 16L. After landing I was to call the sea tower supervisor. I spoke with mr X and explained what had happened. He had not spoken with the air carrier B captain when I called.

Original NASA ASRS Text

Title: ACR HAS NMAC WITH ANOTHER ACR FLT ON VISUAL APCH. TCASII RA.

Narrative: MY FLT WAS VECTORED BY SEA APCH FOR A VISUAL APCH TO RWY 16L AT SEA. I WAS FLYING THE ACFT. APCH ASKED IF WE HAD THE ARPT IN SIGHT, WHICH WE DID. THEY ADVISED THAT AN ACR B FLT WAS ALSO ON A VISUAL TO RWY 16R AND THEY HAD US IN SIGHT. WE SAW THE ACR B ACFT APCHING FROM THE R AND HIGH. APCH CTL ALSO ADVISED THAT AN AIR AMBULANCE WAS ON FINAL TO RWY 32 AT BOEING FIELD. I HAD THAT ACFT IN SIGHT TO THE L AND LOW. WE WERE CLRED FOR A VISUAL APCH TO RWY 16L AND TO CROSS BOEING FIELD AT OR ABOVE 2100. WE CROSSED AT 2100 FT. BTWN BOEING FIELD AND SEATAC THE ACR B FLT PASSED US ON THE APCH. THE ACR B APPEARED TO BE DRIFTING OVER TO 16L AND DSNDING ON TOP OF US. OUR TCASII WENT OFF AND TURNED RED WITH AN RA TO DSND. THE ACR B ALT WAS 1100 ACCORDING TO THE TCASII. I MOVED OVER TO THE L OF THE CENTERLINE OF 16L AND WAS APPROX 800 AGL AND LOOKING UP AT THE ACR ACFT. THE TWR ASKED OUR ALT FROM AN ALERTER GOING OFF IN THE TWR. I TOLD THEM ABOUT THE ACR B ACFT AND THAT I HAD THE GND AND THE FIELD IN SIGHT. HAD I STARTED A GAR I WOULD HAVE HIT THE ACR B ACFT. THE ACR B SAID THEY WERE LINED UP WITH 16R. I SLOWED THE ACFT TO 138 KTS. VREF WAS 124 KTS. I LET THE ACR B GET FURTHER AHEAD OF US AND CONTINUED THE APCH TO 16L AND MADE A SAFE SUCCESSFUL LNDG ON 16L. AFTER LNDG I WAS TO CALL THE SEA TWR SUPVR. I SPOKE WITH MR X AND EXPLAINED WHAT HAD HAPPENED. HE HAD NOT SPOKEN WITH THE ACR B CAPT WHEN I CALLED.

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.