A B-757 captain, on the mod 2 arrival for sfo, reported a TCASII RA in response to the close proximi...

Attributes
ACN	585480
Time
Date	200306
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	intersection : archi
State Reference	CA
Altitude	msl single value : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : nct.tracon
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : nct.tracon
Operator	general aviation : personal
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	climbout : intermediate altitude
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : flight engineer pilot : atp pilot : commercial
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 2100
ASRS Report	585480
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : required legal separation non adherence : published procedure non adherence : far
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 3000 vertical : 100
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Descending on arrival to sfo, about 12 NM east of archi intersection, on mod 2 arrival on the coaldale transition, TCASII alerted, 'traffic.' we observed a yellow square on TCASII, about 4 mi out, at 10 O'clock position and climbing into us right towards the arrival. Other airliner was in middle of transmission, so ATC couldn't help. The offending aircraft was apparently oblivious to san francisco arrival traffic. Shortly, we received an RA to 'descend.' we complied with RA and I visually observed a light twin in climbing banked turn, going aft of us about 8 O'clock position and slightly above. Continued approach and landing uneventfully. Advised ATC.

Original NASA ASRS Text

Title: A B-757 CAPT, ON THE MOD 2 ARR FOR SFO, RPTED A TCASII RA IN RESPONSE TO THE CLOSE PROX OF A LIGHT TWIN.

Narrative: DSNDING ON ARR TO SFO, ABOUT 12 NM E OF ARCHI INTXN, ON MOD 2 ARR ON THE COALDALE TRANSITION, TCASII ALERTED, 'TFC.' WE OBSERVED A YELLOW SQUARE ON TCASII, ABOUT 4 MI OUT, AT 10 O'CLOCK POS AND CLBING INTO US RIGHT TOWARDS THE ARR. OTHER AIRLINER WAS IN MIDDLE OF XMISSION, SO ATC COULDN'T HELP. THE OFFENDING ACFT WAS APPARENTLY OBLIVIOUS TO SAN FRANCISCO ARR TFC. SHORTLY, WE RECEIVED AN RA TO 'DSND.' WE COMPLIED WITH RA AND I VISUALLY OBSERVED A LIGHT TWIN IN CLBING BANKED TURN, GOING AFT OF US ABOUT 8 O'CLOCK POS AND SLIGHTLY ABOVE. CONTINUED APCH AND LNDG UNEVENTFULLY. ADVISED ATC.

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.

A B-757 captain, on the mod 2 arrival for sfo, reported a TCASII RA in response to the close proximity of a light twin.