GLASSAIR 1 PLT FLIES INTO AN AREA FORECAST WITH POSSIBLE ICING CONDITIONS ABOVE 9000 FT 20 MI W OF I58 AFTER DEP.

Narrative

I WAS SITTING IN THE FBO AT PLAINVIEW; TX; GETTING 5 MIN OLD DOPPLER RADAR. I HAD GOTTEN A BRIEFING EARLIER THAT CALLED FOR TSTMS BTWN PLAINVIEW AND SANTA FE (OUR DEST). I SAW A PRECIP FREE WINDOW ALONG V62; CALLED FOR ANOTHER BRIEFING AND WAS TOLD THERE WAS A WINDOW OF OPPORTUNITY FROM PLAINVIEW AND SANTA FE WITH THE FORECAST OF POSSIBLE ICING FROM 9000 FT TO FL210. WE DEPARTED IN LIGHT RAIN AND IMC AT 1100 FT. WE HAD NO PROBS AT 8000 FT AND WERE BTWN LAYERS UNTIL JUST SW OF ANTON CHICO VOR WHERE WE HAD TO GO TO 10000 FT JUST AFTER ANTON CHICO. ALBUQUERQUE TOLD ME THAT HE HAD A PIREP OF LIGHT ICING ABOVE 9000 FT. AS I REACHED 10000 FT; I STARTED PICKING UP RIME ICE. I ASKED FOR HIGHER AND STARTED A CLB; BUT IT QUICKLY BECAME APPARENT THAT I WOULD NOT REACH 12000 FT. THE ICE WAS BUILDING VERY FAST. I COULD NOT MAINTAIN ALT WITH FULL PWR AND STARTED TO DSND. I TOLD ALBUQUERQUE THAT I HAD TO DSND TO HOLD AIRSPD. I DID A 180 DEG TURN TO HEAD BACK TO LOWER TERRAIN. I ASKED FOR VECTORS TO THE NEAREST ARPT AND WAS TOLD THAT SANTA ROSA WAS 12 O'CLOCK POS AND 20 MI. I HEADED FOR SANTA ROSA WHILE STILL IN A DSCNT. I WAS VECTORED OVER THE ARPT AND WITH THE HELP OF MY CERTIFIED GPS; CIRCLED DOWN IN A HALF STANDARD RATE TURN. THE ICE WAS STILL ON THE WING BUT WAS NO LONGER BUILDING. I BROKE OUT; SAW THE ARPT AND MADE A NORMAL LNDG WITH ICE FLYING OFF THE PLANE IN CHUNKS. I CANCELED IFR ON THE GND IN SANTA ROSA. IN HINDSIGHT; I THOUGHT WITH THE WINDOW OF NO PRECIP BTWN PLAINVIEW AND SANTA FE I COULD MAKE IT TO SANTA FE. THE TEMPS IN THE CLOUDS WENT FROM 34 DEGS TO 28 DEGS AS I CLBED TO 10000 FT. THE PIREP OF LIGHT ICING CHANGED TO HVY FAST ICING BY THE TIME I GOT PAST ANTON CHICO AT 10000 FT. THE FORECAST OF THE FREEZING LEVEL AT 9000 FT SHOULD HAVE BEEN A NO-GO DECISION.