Narrative:

The near midair incident occurred at aprox XA55 (PST) at 3000 ft MSL, 2 NM east of sli VOR on a vectored heading of 050 degrees. Coast approach was the controling facility and we were expecting the ILS runway 19R at sna. ATC warned us of traffic 12 O'clock position at our altitude and that we could expect a possible TCASII alert. With traffic approximately 4 NM ahead ATC instructed the traffic to turn right immediately. The traffic was slow to respond and when it did it turned left and descended. We were then told to descend immediately without any instruction as to what altitude or heading. The first officer and I both were ready to respond to a TCASII command when the RA command was initiated by the aircraft's TCASII system. The RA was for an immediate descent straight ahead and the aural warning 'descend, descend' was received. The first officer (PF) immediately responded by smoothly following the TCASII RA descend command and ATC was advised of the descent. At approximately 2600 ft MSL the target symbol merged with our aircraft symbol with a +200 ft deviation. At 2500 ft MSL, removal of the RA descend command and aural 'clear of conflict' was received. At that time ATC was advised that we were returning to our previously assigned altitude and the aircraft was smoothly returned to 3000 ft. No GPWS warnings were received at any time. When clear of the traffic and stabilized to continue vectors for the approach, ATC asked us if we thought the VFR traffic was in VMC conditions. We advised ATC that we were IMC throughout the incident and that the traffic was at our altitude. Vectors were completed and we were cleared for the approach. VMC conditions were obtained at approximately 2000 ft MSL and a normal landing was made without incident. After completing the flight there were no indications from the cabin crew or passenger that a near midair incident was experienced. During the entire incident SOP's were adhered to and good CRM procedures were experienced. The first officer and I thoroughly debriefed the incident after the flight and concluded that we could continue the operation to phx as planned. No further communications with coast approach was made.

Google
 

Original NASA ASRS Text

Title: NMAC BTWN A B737-700 FLC AND AN UNKNOWN 'VMC' ACFT 2 NM E OF SLI FOR A VECTORED APCH TO SNA, CA.

Narrative: THE NEAR MIDAIR INCIDENT OCCURRED AT APROX XA55 (PST) AT 3000 FT MSL, 2 NM E OF SLI VOR ON A VECTORED HEADING OF 050 DEGS. COAST APCH WAS THE CTLING FACILITY AND WE WERE EXPECTING THE ILS RWY 19R AT SNA. ATC WARNED US OF TFC 12 O'CLOCK POS AT OUR ALT AND THAT WE COULD EXPECT A POSSIBLE TCASII ALERT. WITH TFC APPROX 4 NM AHEAD ATC INSTRUCTED THE TFC TO TURN R IMMEDIATELY. THE TFC WAS SLOW TO RESPOND AND WHEN IT DID IT TURNED L AND DSNDED. WE WERE THEN TOLD TO DSND IMMEDIATELY WITHOUT ANY INSTRUCTION AS TO WHAT ALT OR HEADING. THE FO AND I BOTH WERE READY TO RESPOND TO A TCASII COMMAND WHEN THE RA COMMAND WAS INITIATED BY THE ACFT'S TCASII SYS. THE RA WAS FOR AN IMMEDIATE DSCNT STRAIGHT AHEAD AND THE AURAL WARNING 'DSND, DSND' WAS RECEIVED. THE FO (PF) IMMEDIATELY RESPONDED BY SMOOTHLY FOLLOWING THE TCASII RA DSND COMMAND AND ATC WAS ADVISED OF THE DSCNT. AT APPROX 2600 FT MSL THE TARGET SYMBOL MERGED WITH OUR ACFT SYMBOL WITH A +200 FT DEV. AT 2500 FT MSL, REMOVAL OF THE RA DSND COMMAND AND AURAL 'CLR OF CONFLICT' WAS RECEIVED. AT THAT TIME ATC WAS ADVISED THAT WE WERE RETURNING TO OUR PREVIOUSLY ASSIGNED ALT AND THE ACFT WAS SMOOTHLY RETURNED TO 3000 FT. NO GPWS WARNINGS WERE RECEIVED AT ANY TIME. WHEN CLR OF THE TFC AND STABILIZED TO CONTINUE VECTORS FOR THE APCH, ATC ASKED US IF WE THOUGHT THE VFR TFC WAS IN VMC CONDITIONS. WE ADVISED ATC THAT WE WERE IMC THROUGHOUT THE INCIDENT AND THAT THE TFC WAS AT OUR ALT. VECTORS WERE COMPLETED AND WE WERE CLRED FOR THE APCH. VMC CONDITIONS WERE OBTAINED AT APPROX 2000 FT MSL AND A NORMAL LNDG WAS MADE WITHOUT INCIDENT. AFTER COMPLETING THE FLT THERE WERE NO INDICATIONS FROM THE CABIN CREW OR PAX THAT A NEAR MIDAIR INCIDENT WAS EXPERIENCED. DURING THE ENTIRE INCIDENT SOP'S WERE ADHERED TO AND GOOD CRM PROCS WERE EXPERIENCED. THE FO AND I THOROUGHLY DEBRIEFED THE INCIDENT AFTER THE FLT AND CONCLUDED THAT WE COULD CONTINUE THE OP TO PHX AS PLANNED. NO FURTHER COMS WITH COAST APCH WAS MADE.

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.