Narrative:

The second aircraft was a cessna; a single engine -- looked like a C172. On a ferry flight to oak; I was flying with only the flight crew and cabin crew on board. We were talking to norcal on 127.2 on an assigned heading of 340 degrees at 3000 ft MSL approximately 15 NM south of oak. Approach called out traffic at 11 O'clock position and 500 ft below (I do not remember the distance). We were looking for the traffic when all of a sudden approach called traffic alert turn immediately to the left 20 degrees. I turned the autoplt off and used approximately 40 degrees of bank turn left. Just as I started the turn; the TCASII went off with an RA to descend. I kept the turn going and pushed the nose down; descending at approximately 2000 FPM. Going through 2700 ft MSL; we both saw the traffic at about our 1 O'clock position and approximately 500 ft horizontal and 300 ft vertical to us. After telling approach of our RA he told us to descend to 2500 ft MSL intercept the ILS 29 at oak. I know that the airspace around oak/sfo is very busy and congested; but keeping us below the class B airspace going into oak is asking for trouble. I also believe that had I not taken the autoplt off and aggressively bank and descended the aircraft we would have hit the cessna.

Google
 

Original NASA ASRS Text

Title: B737 FLT CREW; BEING VECTORED BY NCT TO OAK; EXPERIENCED A CONFLICT AT 3000 FT WITH UNRPTED ACFT.

Narrative: THE SECOND ACFT WAS A CESSNA; A SINGLE ENG -- LOOKED LIKE A C172. ON A FERRY FLT TO OAK; I WAS FLYING WITH ONLY THE FLT CREW AND CABIN CREW ON BOARD. WE WERE TALKING TO NORCAL ON 127.2 ON AN ASSIGNED HDG OF 340 DEGS AT 3000 FT MSL APPROX 15 NM S OF OAK. APCH CALLED OUT TFC AT 11 O'CLOCK POS AND 500 FT BELOW (I DO NOT REMEMBER THE DISTANCE). WE WERE LOOKING FOR THE TFC WHEN ALL OF A SUDDEN APCH CALLED TFC ALERT TURN IMMEDIATELY TO THE L 20 DEGS. I TURNED THE AUTOPLT OFF AND USED APPROX 40 DEGS OF BANK TURN L. JUST AS I STARTED THE TURN; THE TCASII WENT OFF WITH AN RA TO DSND. I KEPT THE TURN GOING AND PUSHED THE NOSE DOWN; DSNDING AT APPROX 2000 FPM. GOING THROUGH 2700 FT MSL; WE BOTH SAW THE TFC AT ABOUT OUR 1 O'CLOCK POS AND APPROX 500 FT HORIZ AND 300 FT VERT TO US. AFTER TELLING APCH OF OUR RA HE TOLD US TO DSND TO 2500 FT MSL INTERCEPT THE ILS 29 AT OAK. I KNOW THAT THE AIRSPACE AROUND OAK/SFO IS VERY BUSY AND CONGESTED; BUT KEEPING US BELOW THE CLASS B AIRSPACE GOING INTO OAK IS ASKING FOR TROUBLE. I ALSO BELIEVE THAT HAD I NOT TAKEN THE AUTOPLT OFF AND AGGRESSIVELY BANK AND DSNDED THE ACFT WE WOULD HAVE HIT THE CESSNA.

Data retrieved from NASA's ASRS site as of January 2009 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.