NMAC BTWN A C172 CLBING OUT OF 4000 FT AND A DSNDING A320 5 MI NW OF AVX; CA.

Narrative

AFTER DEPARTING CATALINA ISLAND; CLBING THROUGH 3000 FT; INTENDED TO CLB TO 5500 FT; ENRTE TO LONG BEACH; PLT CONTACTED SOCAL APCH FOR FLT FOLLOWING. WE WERE ASKED TO IDENT AND SAY AGAIN REQUEST. I BELIEVE WE WERE THEN GIVEN A XPONDER CODE. WE WERE NEVER GIVEN 'RADAR CONTACT.' AT APPROX 4500 FT; WE SAW AN A320 AT OUR 9 O'CLOCK POS; BELOW US; ON A PERPENDICULAR TRACK. WE STAYED AT 4500 FT AND THEY PASSED BENEATH US. THE CTLR NEVER CAME BACK TO US WITH ANY REPLY. THE CTLR DID TELL A320; 'SORRY ABOUT THAT LATE CALL ON THE VFR TFC.' WE PROCEEDED TOWARD LONG BEACH AND THEN DSNDED TO 3500 FT; CONTACTED SOCAL ON THE NEXT FREQ AND LANDED. THIS AIRSPACE IS HIGHLY CONGESTED; ESPECIALLY ON SUNDAY; AND I WAS SURPRISED TO SEE AN ACR JET THAT LOW ABEAM THE E SIDE OF CATALINA HEADING SE. THE AIRLINER WAS NOT ON THE AIRWAY OR THE INST APCH INTO LGB. I ALSO NOTED THE TCA CHART HAS JET TFC DEPICTED AT 6000 FT INBOUND TO AVX WHEREAS THE APCH INTO LGB SHOWS 4000 FT. THE FREQ WAS CONGESTED. THERE WAS ALSO ANOTHER GA ACFT WHICH DEPARTED PRIOR TO US REQUESTING THE SAME; 3000 FT CLBING TO 5500 FT AND FLT FOLLOWING. MY ATTN WAS DIVERTED TO SCANNING FOR THIS TFC. IT IS POSSIBLE THE CTLRS THOUGHT WE WERE THE SAME ACFT. ANOTHER OBSERVER IN OUR ACFT RPTED HE HEARD ATC TELL THE A320 TO DSND. THE TFC AROUND CATALINA ISLAND IS ALWAYS HIGHLY CONGESTED ON VFR DAYS; ESPECIALLY WEEKENDS. ALLOWING THE AIRLINER TO DSND INTO THIS TFC SEEMS UNSAFE DURING THESE PEAK PERIODS. WE; BEING VFR ACFT; WERE OUTSIDE THE CLASS B AIRSPACE AND NEVER REACHED THE FLOOR OF 5000 FT. SUPPLEMENTAL INFO FROM ACN 591720: THE AIRBUS WAS OFF THE V27 AIRWAY; BELOW 4000 FT MSL. AFTER THE NEAR MISS; THE CTLR APOLOGIZED TO THE AIRBUS AND TOLD HIM IT WAS VERY BUSY.