C180 PLT COLLIDES WITH ANOTHER ACFT WHILE TAXIING AT FWS.

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TAXI INSTRUCTIONS FROM SPINKS (FWS) GND WAS TO TAXI TO RWY 17R AND HOLD SHORT. I TAXIED ON TXWY A AT THE S END OF THE RWY TO RWY 17R AT THE N END OF RWY (ABOUT 6000 FT). FORWARD VISION IN A C180 IS SOMEWHAT LIMITED; SO I EXECUTED S-TURNS DURING TAXI FOR BETTER VISIBILITY. I SAW A LOW WING ACFT AT THE RWY 17R HOLD AREA WHEN I WAS ABOUT 3000 FT FROM THE N END OF RWY. AS I REACHED THE N END OF THE TXWY; I STARTED A GENTLE R-HAND TURN TO THE HOLD/RUN-UP AREA (ABOUT 150 FT IN FRONT OF ME). AS I WAS TURNING; MY GLASSES SLIPPED DOWN MY NOSE; AND I REACHED UP WITH MY R HAND TO PUSH THEM BACK UP INTO POS (1-2 SECONDS). WHEN I LOOKED FORWARD AGAIN; MY AIRPLANE (C180) WAS SLOWLY CONTINUING A R TURN AND THE OTHER ACFT SUDDENLY CAME INTO VIEW AND WAS ONLY 10-20 FT IN FRONT OF ME. MY GND SPD WAS LOW (6-8 KTS) AND THE ENG RPM WAS 750-800. I BRAKED AND PULLED THE THROTTLE BACK; BUT STILL COLLIDED WITH THE R REAR OF THE PA28 ON THE HORIZ TAIL. THE PA28 WAS AT REST WHEN THE ACCIDENT OCCURRED. I HAD THOUGHT THE PA28 WAS 50-100 FT FURTHER IN FRONT OF ME; BUT DUE TO THE NOSE HIGH ATTITUDE OF THE C180; I MOMENTARILY LOST SIGHT OF THE PA28 IN THE R TURN I WAS MAKING.