Narrative:

During descent on the arrival into smf; we received a traffic call from norcal approach concerning traffic at our 12 O'clock position; type and altitude unknown. The captain was flying the aircraft with the autoplt engaged during the descent. We were cleared to 4000 ft in the descent. I visually acquired the aircraft at around 4600 ft; and advised the captain that the target had no relative motion. TCAS sounded at about this time with a TA. We leveled at 4000 ft and I told the captain we needed to descend now because of the collision hazard. The captain finally saw the aircraft in our windscreen; disconnected the autoplt and dove under the other aircraft. It was a eurocoupe private aircraft and we were overtaking on approximately the same heading. We were 236 degree heading; the eurocoupe was approximately a 250 degree heading. We did not get an RA; most likely because the aircraft was using a mode a transponder. Miss was close to 400 ft vertically.

Google
 

Original NASA ASRS Text

Title: CARJ AND SMA HAVE NMAC NEAR SMF.

Narrative: DURING DSCNT ON THE ARR INTO SMF; WE RECEIVED A TFC CALL FROM NORCAL APCH CONCERNING TFC AT OUR 12 O'CLOCK POS; TYPE AND ALT UNKNOWN. THE CAPT WAS FLYING THE ACFT WITH THE AUTOPLT ENGAGED DURING THE DSCNT. WE WERE CLRED TO 4000 FT IN THE DSCNT. I VISUALLY ACQUIRED THE ACFT AT AROUND 4600 FT; AND ADVISED THE CAPT THAT THE TARGET HAD NO RELATIVE MOTION. TCAS SOUNDED AT ABOUT THIS TIME WITH A TA. WE LEVELED AT 4000 FT AND I TOLD THE CAPT WE NEEDED TO DSND NOW BECAUSE OF THE COLLISION HAZARD. THE CAPT FINALLY SAW THE ACFT IN OUR WINDSCREEN; DISCONNECTED THE AUTOPLT AND DOVE UNDER THE OTHER ACFT. IT WAS A EUROCOUPE PVT ACFT AND WE WERE OVERTAKING ON APPROX THE SAME HDG. WE WERE 236 DEG HDG; THE EUROCOUPE WAS APPROX A 250 DEG HDG. WE DID NOT GET AN RA; MOST LIKELY BECAUSE THE ACFT WAS USING A MODE A XPONDER. MISS WAS CLOSE TO 400 FT VERTICALLY.

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.