C172 PLT REPORTS NMAC WITH OVERTAKING CIRRUS. IS FORCED TO TAKE EVASIVE ACTION WITHOUT VISUAL CONTACT DUE TO ENCROACHING MONITORED ON THE TIS DISPLAY AND APPARENT IMMINENT COLLISION.

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SOCAL APCH ADVISED ME OF A CIRRUS AT MY 6 O'CLOCK POS AND AT 3500 FT; AND GAINING ON ME BY 30 KTS. SOCAL APCH ADVISED THE CIRRUS OF MY SKYHAWK PRESENCE. I THINK THE CIRRUS PLT SAID HE WAS LOOKING FOR ME. HE MAY HAVE SAID THAT HE WAS BEGINNING HIS DSCNT TO A LOWER ALT; MAYBE TO 2500 FT; MY ALT. I SAW A REAR DISPLAY ON MY TIS OF A TARGET AT +10; RELATIVE ALT OF 1000 FT. I WAS AT 2500 FT MSL. I THINK I HAD ANOTHER TARGET OR 2 ON MY TIS SOMEWHERE AROUND ME. ABOUT A MIN LATER OR TWO AT THE MOST; THE CIRRUS PLT CALLED; 'SKYHAWK TFC IN SIGHT.' I LOOKED AT MY TIS DISPLAY ON A GARMIN 430 GPS PANEL MOUNT UNIT; AND IT SHOWED TFC +3 (300 FT RELATIVE ALT) AND BEHIND ME; AND CLOSER BEHIND ME. IT WAS THE ONLY PING BY NOW; I THINK; AND I DON'T KNOW WHAT HAPPENED TO THE OTHER PINGS. THEN IT WENT TO +02; +01; THEN A YELLOW CIRCLE AT 00; WHICH MEANS AT MY ALT OF 2500 FT; AND A PROX WARNING BY THE TIS; A YELLOW CIRCLE. I WATCHED THE PING GET CLOSER AND CLOSER TO THE CIRCLE; THEN CTR CIRCLE; AND HELD STEADY AT 00 RELATIVE ALT; WHICH IS STILL 2500 FT MSL. THIS TOOK ABOUT 15-30 SECONDS MY BEST GUESS. THEN I BEGAN A DSCNT OF ABOUT 300 FPM; A SHALLOW DSCNT; AS AN EVASIVE ACTION MANEUVER. THEN THE CIRRUS BUZZED RIGHT OVER ME WHEN I WAS AT 2300 FT MSL; 10-20 FT MAX HT DISTANCE DIRECTLY OVERHEAD ABOVE ME. I THEN CALLED SOCAL APCH AND TOLD THEM THAT THE CIRRUS 'JUST FLEW RIGHT OVERHEAD OF ME; 50 FT OR SO AT THE MOST;' OR SIMILAR WORDS TO THAT EFFECT. SOCAL APCH HAD NO RESPONSE TO MY RADIO CALL. IT WAS ACTUALLY 10-20 FT ABOVE AT THE MOST WHEN I THINK BACK ON IT. I HEARD HIS ENG ROARING THROUGH MY HEADSET; THE PLANE THAT I WAS IN HAS 2 OVERHEAD SKYLIGHT WINDOWS; WHICH SHADOWED ON HIS OVERPASS; AND HIS WINGSPAN WAS ALMOST AS WIDE AS MINE. THOSE ARE MY JUDGEMENT FACTORS; PLUS THE IMAGE FILLED MY WINDSCREEN INITIALLY. I HAD A PAX ABOARD WHO SAW IT TOO.