Narrative:

En route from psp to lax, level flight at 8500' VFR on top clearance, 25 NM east of pdz VORTAC inbound on the 072 degree right (V388). An small aircraft very suddenly appeared at my 11 O'clock to 11:30 position, same altitude, but on a northwest course. My immediate reaction (I was the PNF and the first one to see the small aircraft) was to initiate a diving right-hand turn. We missed collision by the distances stated above. I feel that had I seen and reacted to the small aircraft just 1 second later, collision would have been imminent. I immediately reported the incident to ont approach control (119.65). A few moments later I asked the controller if he had been talking to the subject small aircraft. The controller stated that he had not been talking to that aircraft but that immediately after I made my near miss report, said aircraft had called asking for traffic advisories (I must have missed that call by the small aircraft as I was off frequency for a moment apologizing to all my passenger). I continued, and told ont approach that I had never been so close to another aircraft in my 3100 hours of flying. He was, in turn, apologetic, but said that the small aircraft was not squawking altitude. At the end of that statement, he gave me a frequency change. Before I could switch frequencys, however, I heard the small aircraft pilot came on frequency and assertively state that he did have altitude encoding equipment and it was turned on prior to the near midair. It was a frightful experience that reconfirms wht I already knew: always make a conscious effort to keep up a good outside traffic scan and reduce as much as safely possible the amount of time spent inside the cockpit. Everyone makes mistakes; I definitely think the controller did this time.

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Original NASA ASRS Text

Title: CLOSE PROX COMMUTER LTT OPERATING VFR ON TOP AND GA SMA VFR CRUISE.

Narrative: ENRTE FROM PSP TO LAX, LEVEL FLT AT 8500' VFR ON TOP CLRNC, 25 NM E OF PDZ VORTAC INBND ON THE 072 DEG R (V388). AN SMA VERY SUDDENLY APPEARED AT MY 11 O'CLOCK TO 11:30 POS, SAME ALT, BUT ON A NW COURSE. MY IMMEDIATE REACTION (I WAS THE PNF AND THE FIRST ONE TO SEE THE SMA) WAS TO INITIATE A DIVING RIGHT-HAND TURN. WE MISSED COLLISION BY THE DISTANCES STATED ABOVE. I FEEL THAT HAD I SEEN AND REACTED TO THE SMA JUST 1 SEC LATER, COLLISION WOULD HAVE BEEN IMMINENT. I IMMEDIATELY RPTED THE INCIDENT TO ONT APCH CTL (119.65). A FEW MOMENTS LATER I ASKED THE CTLR IF HE HAD BEEN TALKING TO THE SUBJECT SMA. THE CTLR STATED THAT HE HAD NOT BEEN TALKING TO THAT ACFT BUT THAT IMMEDIATELY AFTER I MADE MY NEAR MISS RPT, SAID ACFT HAD CALLED ASKING FOR TFC ADVISORIES (I MUST HAVE MISSED THAT CALL BY THE SMA AS I WAS OFF FREQ FOR A MOMENT APOLOGIZING TO ALL MY PAX). I CONTINUED, AND TOLD ONT APCH THAT I HAD NEVER BEEN SO CLOSE TO ANOTHER ACFT IN MY 3100 HRS OF FLYING. HE WAS, IN TURN, APOLOGETIC, BUT SAID THAT THE SMA WAS NOT SQUAWKING ALT. AT THE END OF THAT STATEMENT, HE GAVE ME A FREQ CHANGE. BEFORE I COULD SWITCH FREQS, HOWEVER, I HEARD THE SMA PLT CAME ON FREQ AND ASSERTIVELY STATE THAT HE DID HAVE ALT ENCODING EQUIP AND IT WAS TURNED ON PRIOR TO THE NEAR MIDAIR. IT WAS A FRIGHTFUL EXPERIENCE THAT RECONFIRMS WHT I ALREADY KNEW: ALWAYS MAKE A CONSCIOUS EFFORT TO KEEP UP A GOOD OUTSIDE TFC SCAN AND REDUCE AS MUCH AS SAFELY POSSIBLE THE AMOUNT OF TIME SPENT INSIDE THE COCKPIT. EVERYONE MAKES MISTAKES; I DEFINITELY THINK THE CTLR DID THIS TIME.

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.