Narrative:

As I continued my descent inbound to the airfield my first officer and I noticed that the air traffic controller was being supervised (every so often another controller would come on the frequency and countermand instructions given by my controller to other aircraft). From here the story evolves. At approximately 15 mi from long beach I was cleared to 4000'. On the descent and passing 4800' I was told by the controller to level at 5000'. I abruptly stopped my descent and reclimbed back to 5000'. I was told by the controller that IFR traffic would be at 4000' (another medium large transport Y) and pass below me from left to right. At about the same time I observed the medium large transport Y below me, my first officer and I noticed an small transport Z at our 10 O'clock position at our same altitude and in a very sharp left turn to avoid us. About the same time the supervisor controller came on and told us to make an immediate right turn and descend to 4000'. The turn was an 80 degree turn away from the traffic and airport. The controller then asked me if I saw the traffic, which I acknowledged. I also sensed the supervisor controller was very upset, not to mention the controller she was supervising or the commuter pilot who took evasive action. At no time did I feel my flight was in jeopardy and a routine approach and landing followed. Among contributing factors I believe led to this incident were: proliferation of heavy light aircraft operations along the coast because of nice WX and a sunday afternoon. Controller saturation with traffic calls. Leveling off at an altitude to allow adequate IFR sep for passing traffic unaware that the altitude was also occupied by closing traffic toward my aircraft, also probably due to traffic controller overload. Failure of either the student controller of supervisor to recognize the traffic conflicts of 3 aircraft until they were literally on top of each other (unplanned).

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Original NASA ASRS Text

Title: NMAC BETWEEN ACR-MLG AND ACR-SMT. ALSO LESS THAN STANDARD SEPARATION BETWEEN ACR-MLG AND SECOND ACR-MLG AT THE SAME TIME. OPERATIONAL ERROR.

Narrative: AS I CONTINUED MY DSCNT INBND TO THE AIRFIELD MY F/O AND I NOTICED THAT THE AIR TFC CTLR WAS BEING SUPERVISED (EVERY SO OFTEN ANOTHER CTLR WOULD COME ON THE FREQ AND COUNTERMAND INSTRUCTIONS GIVEN BY MY CTLR TO OTHER ACFT). FROM HERE THE STORY EVOLVES. AT APPROX 15 MI FROM LONG BEACH I WAS CLRED TO 4000'. ON THE DSCNT AND PASSING 4800' I WAS TOLD BY THE CTLR TO LEVEL AT 5000'. I ABRUPTLY STOPPED MY DSCNT AND RECLIMBED BACK TO 5000'. I WAS TOLD BY THE CTLR THAT IFR TFC WOULD BE AT 4000' (ANOTHER MLG Y) AND PASS BELOW ME FROM LEFT TO RIGHT. AT ABOUT THE SAME TIME I OBSERVED THE MLG Y BELOW ME, MY F/O AND I NOTICED AN SMT Z AT OUR 10 O'CLOCK POS AT OUR SAME ALT AND IN A VERY SHARP LEFT TURN TO AVOID US. ABOUT THE SAME TIME THE SUPVR CTLR CAME ON AND TOLD US TO MAKE AN IMMEDIATE RIGHT TURN AND DSND TO 4000'. THE TURN WAS AN 80 DEG TURN AWAY FROM THE TFC AND ARPT. THE CTLR THEN ASKED ME IF I SAW THE TFC, WHICH I ACKNOWLEDGED. I ALSO SENSED THE SUPVR CTLR WAS VERY UPSET, NOT TO MENTION THE CTLR SHE WAS SUPERVISING OR THE COMMUTER PLT WHO TOOK EVASIVE ACTION. AT NO TIME DID I FEEL MY FLT WAS IN JEOPARDY AND A ROUTINE APCH AND LNDG FOLLOWED. AMONG CONTRIBUTING FACTORS I BELIEVE LED TO THIS INCIDENT WERE: PROLIFERATION OF HEAVY LIGHT ACFT OPS ALONG THE COAST BECAUSE OF NICE WX AND A SUNDAY AFTERNOON. CTLR SATURATION WITH TFC CALLS. LEVELING OFF AT AN ALT TO ALLOW ADEQUATE IFR SEP FOR PASSING TFC UNAWARE THAT THE ALT WAS ALSO OCCUPIED BY CLOSING TFC TOWARD MY ACFT, ALSO PROBABLY DUE TO TFC CTLR OVERLOAD. FAILURE OF EITHER THE STUDENT CTLR OF SUPVR TO RECOGNIZE THE TFC CONFLICTS OF 3 ACFT UNTIL THEY WERE LITERALLY ON TOP OF EACH OTHER (UNPLANNED).

Data retrieved from NASA's ASRS site as of August 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.