IFR ACFT HAS NMAC WITH PARADROP ACFT DSNDING NEAR THE AIRWAY.

Narrative

I WAS APCHING MY FINAL DEST; SKY HARBOR; AZ; ON AN IFR FLT PLAN WITH THE VISIBILITY MARGINAL; CAUSED BY THE SUN. TFC WAS EXTREMELY DIFFICULT TO VISUALLY SPOT. ON EITHER PHOENIX OR ALBUQUERQUE APCH I HEARD ANOTHER SMALL ACFT RPTING A NEAR MISS. IMMEDIATELY I TURNED TO MY 6 O'CLOCK AND SPOTTED THE TFC (SMALL HIGH WING). THE TFC FIRST INQUIRED THE APCH CTLR ABOUT THE NEAR MISS COMPLAINING THAT HE WAS TO RECEIVE RADAR COVERAGE FROM THEIR SPIRALING DSCNT FROM 14000 AFTER DROPPING JUMPERS. THE APCH CTLR RETURNED STATING THAT NO TFC HAD BEEN SEEN ON RADAR. WITH A VISUAL ON THE SPIRALING TFC; NOW A MI BEHIND; I IMMEDIATELY QUESTIONED THE CTLR. I STATED MY CALL SIGN; LOCATION; AND THE POSSIBILITY OF BEING THE TFC IN THE NEAR COLLISION. ALSO; I ASKED IF I MYSELF WAS ON RADAR COVERAGE GIVING MY SQUAWK CODE; CONCERNED BECAUSE I MYSELF WAS FILED AS IFR AND SHOULD HAVE BEEN WARNED ABOUT THE TFC BEHIND ME. UPON MY REQUEST THERE WAS NO IMMEDIATE ANSWER. HOWEVER; AFTER A SHORT PAUSE; I WAS REQUESTED TO DSND TO 8000 FROM MY CRUISE OF 10000. THIS SITUATION AROSE FROM A SPIRALING DSCNT OF ONE ACFT ONTO ANOTHER LOWER ACFT; LIMITING THE VISIBILITY OF BOTH. WITHOUT WARNING OF TFC SUCH AS THIS; VERY SERIOUS SITUATIONS CAN ARISE.