Air carrier X had less than standard TCA separation from small aircraft Y. System error.

Attributes
ACN	177157
Time
Date	199104
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : sfo
State Reference	CA
Altitude	msl bound lower : 3000 msl bound upper : 3300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	approach : visual
Flight Plan	IFR
Aircraft 2
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	cruise other
Route In Use	enroute : direct
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 220 flight time total : 18000 flight time type : 300
ASRS Report	177157
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : nmac non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 300
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X on a quiet bridge visibility approach to runway 28R sfo. We were advised to follow a company medium large transport to airport that was landing 28L. We were advised to let ATC know if we had company in sight. The aircraft was to our left 3000' and below our flight path 1000', and at least 20 KTS faster. We were just above G/south and cleared for a visibility approach to runway 28R sfo. We were advised of traffic at 3000', but we did not see the traffic and never advised ATC that we had the traffic. We could not believe that a single engine small aircraft would be allowed to cross the landing flight path of sfo runway 28 complex at 3000'. We were advised that we missed the aircraft by 300', but he never had visibility contact with us, and we never had a visibility on him. We were asked to call ATC and a discussion of the problem occurred between the captain and ATC supervisor. I feel we both learned a lesson that we must make it 'perfectly clear' what all aircraft are doing.

Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD TCA SEPARATION FROM SMA Y. SYSTEM ERROR.

Narrative: ACR X ON A QUIET BRIDGE VIS APCH TO RWY 28R SFO. WE WERE ADVISED TO FOLLOW A COMPANY MLG TO ARPT THAT WAS LNDG 28L. WE WERE ADVISED TO LET ATC KNOW IF WE HAD COMPANY IN SIGHT. THE ACFT WAS TO OUR LEFT 3000' AND BELOW OUR FLT PATH 1000', AND AT LEAST 20 KTS FASTER. WE WERE JUST ABOVE G/S AND CLRED FOR A VIS APCH TO RWY 28R SFO. WE WERE ADVISED OF TFC AT 3000', BUT WE DID NOT SEE THE TFC AND NEVER ADVISED ATC THAT WE HAD THE TFC. WE COULD NOT BELIEVE THAT A SINGLE ENG SMA WOULD BE ALLOWED TO CROSS THE LNDG FLT PATH OF SFO RWY 28 COMPLEX AT 3000'. WE WERE ADVISED THAT WE MISSED THE ACFT BY 300', BUT HE NEVER HAD VIS CONTACT WITH US, AND WE NEVER HAD A VIS ON HIM. WE WERE ASKED TO CALL ATC AND A DISCUSSION OF THE PROB OCCURRED BTWN THE CAPT AND ATC SUPVR. I FEEL WE BOTH LEARNED A LESSON THAT WE MUST MAKE IT 'PERFECTLY CLR' WHAT ALL ACFT ARE DOING.

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.