Narrative:

I was IFR from cos to sbs on sep/tue/05. There was convective activity along the front range. I checked the WX prior to my departure to my departure and it showed most of the activity over the front range; east of my track. After takeoff and climbing through 17000 ft; I asked for clearance to deviate. The controller granted clearance to deviate. Thunderstorms required several deviations and altitude changes. Onboard radar indicated light precipitation through a corridor between cells. This quickly closed in on me. I immediately attempted to contact center but he was busy and I could not get in to him. The aircraft started to ice (light to moderate) which required an immediate course change. The controller stated that I was IFR which required clearance to deviation and I should have asked. I eventually was cleared to descend into VFR conditions and canceled. Contributing factors: fast moving WX system; convective activity; radio congestion; turbulence and ice and repeatedly blocked radio xmissions. Radar summary chart showed most of the activity to the east of my track. This quickly changed. I should have considered returning to my departure airport.

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Original NASA ASRS Text

Title: A PC12 PLT ON AN IFR FLT PLAN FROM COS TO SBS ENCOUNTERED UNEXPECTED CONVECTIVE ACTIVITY AND ICING. HE DEVIATED AND DSNDED TO CLR THE WX.

Narrative: I WAS IFR FROM COS TO SBS ON SEP/TUE/05. THERE WAS CONVECTIVE ACTIVITY ALONG THE FRONT RANGE. I CHKED THE WX PRIOR TO MY DEP TO MY DEP AND IT SHOWED MOST OF THE ACTIVITY OVER THE FRONT RANGE; E OF MY TRACK. AFTER TKOF AND CLBING THROUGH 17000 FT; I ASKED FOR CLRNC TO DEVIATE. THE CTLR GRANTED CLRNC TO DEVIATE. TSTMS REQUIRED SEVERAL DEVS AND ALT CHANGES. ONBOARD RADAR INDICATED LIGHT PRECIP THROUGH A CORRIDOR BTWN CELLS. THIS QUICKLY CLOSED IN ON ME. I IMMEDIATELY ATTEMPTED TO CONTACT CTR BUT HE WAS BUSY AND I COULD NOT GET IN TO HIM. THE ACFT STARTED TO ICE (LIGHT TO MODERATE) WHICH REQUIRED AN IMMEDIATE COURSE CHANGE. THE CTLR STATED THAT I WAS IFR WHICH REQUIRED CLRNC TO DEV AND I SHOULD HAVE ASKED. I EVENTUALLY WAS CLRED TO DSND INTO VFR CONDITIONS AND CANCELED. CONTRIBUTING FACTORS: FAST MOVING WX SYS; CONVECTIVE ACTIVITY; RADIO CONGESTION; TURB AND ICE AND REPEATEDLY BLOCKED RADIO XMISSIONS. RADAR SUMMARY CHART SHOWED MOST OF THE ACTIVITY TO THE E OF MY TRACK. THIS QUICKLY CHANGED. I SHOULD HAVE CONSIDERED RETURNING TO MY DEP ARPT.

Data retrieved from NASA's ASRS site as of January 2009 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.