Narrative:

WX at sna was sky obscured 1000 ft overcast, visibility 2 mi, rain, fog with the tops at 8000 ft. We were vectored across the localizer for a right downwind at 170 KTS. On base leg we were asked to slow to 150 KTS, we complied. On the intercept heading we were cleared for the ILS runway 19R and instructed to slow to approach speed. We crossed lemon intersection at 135 KTS (approach speed) and contacted the tower. Tower issued a go around for slow GA aircraft on the approach ahead of us. Now on the second approach, intercept heading to the localizer, we were issued a clearance to descend to 3000 ft, maintain 3000 ft till established, cleared for the ILS approach runway 19R. Established inbound, IMC, outside of snake intersection at 3000 ft a TA popped up on the TCASII 500 ft below. I asked approach control if he had the traffic. During my transmission the target showed 400 ft then 300 ft below and climbing. The controller said, 'your cleared to 4000 ft.' I instructed the first officer to execute a missed approach, simultaneously we received an RA to 'climb climb climb now.' in the time the go around was accomplished the target, on the TCASII, was shown at our altitude and passed through our airplane symbol. TCASII issued a 'clear of conflict' command shortly after. We were issued a right downwind vector for another approach, which was routine. We were IMC the entire time below 8000 ft and did not have ground contact until 500 ft AGL.

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Original NASA ASRS Text

Title: NMAC. POSSIBLE OP ERROR.

Narrative: WX AT SNA WAS SKY OBSCURED 1000 FT OVCST, VISIBILITY 2 MI, RAIN, FOG WITH THE TOPS AT 8000 FT. WE WERE VECTORED ACROSS THE LOC FOR A R DOWNWIND AT 170 KTS. ON BASE LEG WE WERE ASKED TO SLOW TO 150 KTS, WE COMPLIED. ON THE INTERCEPT HDG WE WERE CLRED FOR THE ILS RWY 19R AND INSTRUCTED TO SLOW TO APCH SPD. WE CROSSED LEMON INTXN AT 135 KTS (APCH SPD) AND CONTACTED THE TWR. TWR ISSUED A GAR FOR SLOW GA ACFT ON THE APCH AHEAD OF US. NOW ON THE SECOND APCH, INTERCEPT HDG TO THE LOC, WE WERE ISSUED A CLRNC TO DSND TO 3000 FT, MAINTAIN 3000 FT TILL ESTABLISHED, CLRED FOR THE ILS APCH RWY 19R. ESTABLISHED INBOUND, IMC, OUTSIDE OF SNAKE INTXN AT 3000 FT A TA POPPED UP ON THE TCASII 500 FT BELOW. I ASKED APCH CTL IF HE HAD THE TFC. DURING MY XMISSION THE TARGET SHOWED 400 FT THEN 300 FT BELOW AND CLBING. THE CTLR SAID, 'YOUR CLRED TO 4000 FT.' I INSTRUCTED THE FO TO EXECUTE A MISSED APCH, SIMULTANEOUSLY WE RECEIVED AN RA TO 'CLB CLB CLB NOW.' IN THE TIME THE GAR WAS ACCOMPLISHED THE TARGET, ON THE TCASII, WAS SHOWN AT OUR ALT AND PASSED THROUGH OUR AIRPLANE SYMBOL. TCASII ISSUED A 'CLR OF CONFLICT' COMMAND SHORTLY AFTER. WE WERE ISSUED A R DOWNWIND VECTOR FOR ANOTHER APCH, WHICH WAS ROUTINE. WE WERE IMC THE ENTIRE TIME BELOW 8000 FT AND DID NOT HAVE GND CONTACT UNTIL 500 FT AGL.

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.