NMAC.

Narrative

OUR ACFT WAS CLRED TO MODESTO AND THE ASSOCIATED ARR INTO SFO. THE INITIAL CLRNC WAS TO 17000 FT. THE CTLR CALLED OUT THE CPR LTT TFC AT 10 O'CLOCK AND 4 MI. WE SAID WE HAD IT. BOTH THE PLT AND MYSELF (THE SO) HAD THE LTT Y IN SIGHT ON A PARALLEL FLT PATH AND CLRLY IN SIGHT. AFTER WE SAID THE TFC WAS IN SIGHT; OAKLAND ATC RECLRED US 'TO 11000 TO PASS UNDER THE TFC.' THE PLT HAD THE SPD BRAKES OUT PARTIALLY AND WAS DSNDING AT ROUGHLY 4000 FPM. THE CONFLICT WASN'T READILY APPARENT UNTIL THE ACTUAL COLOR OF THE LTT WAS APPARENT. I SAID 'BANK R' AT THE SAME TIME THE PLT TURNED R. I KEPT THE LTT IN SIGHT OUT THE L WINDOW. WHEN THE LTT TURNED L; HIS UNDERWING SURFACE GAVE THE ILLUSION OF EVEN CLOSER PROX. BECAUSE THE SPD BRAKES WERE PARTIALLY OUT; OUR TURN RATE WAS GREATLY MAGNIFIED AS THE SPOILERS ASSISTED IN OUR TURN. THIS RESULTED IN A G-FORCE OF APPROX 2-2 1/2 G'S. I KEPT THE TFC IN SIGHT AND WHEN I SAID WE WERE WELL CLR; WE LEVELED AT 11000. I MADE AN IMMEDIATE PA TO THE PAX. WHEN WE SWITCHED FREQS TO ANOTHER OAKLAND CTLR; THE LTT WAS BEING TOLD HE SHOULD HAVE BEEN ON FREQ IN HIS AREA. (THE LTT WAS OPERATING VFR AND NOT ON OUR FREQ WHEN THE INCIDENT HAPPENED). IN MY OPINION; THERE WERE 2 MAJOR FACTORS THAT CONTRIBUTED TO OUR ROLE IN THIS INCIDENT. THE FIRST WAS THE MINDSET OF MOST PLTS WHO OPERATE ON AN IFR FLT PLAN. THAT IS WHEN CLRED ON AIRWAY; ARR; ETC.; WE THINK THAT A DEV OFF COURSE WILL GET US IN TROUBLE. HENCE; A REAL HESITATION TO TURN AWAY. WE WERE ALSO CLRED TO 11000 TO PASS UNDER THE TFC; WHICH LURED US INTO THINKING A TURN WOULDN'T BE NECESSARY. THE SECOND FACTOR WAS OUR ACCEPTANCE OF PARALLEL TFC INTO CONDENSED TFC AREAS WITH PARALLEL RWYS. SINCE WE WERE GOING INTO THE BAY AREA; IT DIDN'T SEEM UNUSUAL TO SEE OTHER TFC THAT CLOSE. WE DIDN'T KNOW AT THE TIME HE WASN'T ON FREQ. BECAUSE OF HIS SMALL SIZE; HIS CLOSURE WAS ALMOST INSIDIOUS. ONLY WHEN WE COULD DISTINGUISH SEVERAL FEATURES OF THE PLANE DID WE REALIZE HE WASN'T ON A PARALLEL COURSE; BUT CLOSING AND DSNDING AT A SIMILAR RATE.