B737 PF ON VECTOR TO FINAL FAILS TO HEAR TURN TO INSTRUCTIONS AND OVERSHOOTS THE FINAL APCH COURSE.

Narrative

ON VECTOR FOR ILS RWY 9R PHL. ON A HEADING OF 060 DEGS WE WERE EXPECTING EITHER A TURN TO A BASE OR A DOGLEG TO FINAL. WHILE TRYING TO INSERT A CHANGE INTO FMC; APCH CTLR GAVE US A FREQ CHANGE TO THE FINAL CTLR WITH A HEADING CHANGE. FO WAS FLYING; DID NOT HEAR HEADING CHANGE. I HEARD IT BUT BY THE TIME I CHANGED FREQ I REALIZED WE HAD NOT BEGUN TO TURN AND WAS NOW UNSURE OF WHAT THE NEW HEADING WAS SUPPOSED TO BE. I ADVISED CTLR ON CHK-IN THAT WE HAD NOT TURNED YET; STILL ON A HEADING OF 060 DEGS. HE GAVE US AN IMMEDIATE L TURN TO 270 DEGS. WE INITIATED TURN; I OBSERVED TCASII TARGET 400 FT OFF OUR ALT PASS APPROX 2.5 TO 3.0 MI OFF OUR STARBOARD. NO TCASII ALERT OR RESOLUTION. I ASSUMED FO HEARD HEADING CHANGE AND WHILE PREOCCUPIED WITH FMC AND RADIO FREQ CHANGE; I DID NOT NOTICE OUR FAILURE TO TURN UNTIL CHKING IN WITH FINAL CTLR. CONCLUSIONS: 1) LEAVE FMC ALONE DURING HIGH WORKLOAD! 2) WAS NOT EXPECTING TURN TO DOWNWIND SO TURN SUBCONSCIOUSLY DIDN'T MAKE SENSE. WHEN ATC PLANS COURSE REVERSAL FOR A DOWNWIND A HEADS UP SHOULD BE GIVEN. 3) NUMBER OVERLOAD; 4 DIGIT FLT NUMBER; 3 DIGIT HEADING CHANGE; 5 DIGIT FREQ CHANGE; ALL IN SAME XMISSION.