Narrative:

I was given an altitude change from 8000 to 6000' at my discretion. I elected to comply immediately. This new altitude placed me in a cloud formation with moderate turbulence. I was immediately iced over with a heavy layer of clear ice. The windshield, as well as the wings, stabilizers and control surfaces were immediately encrusted. I reported my conditions and asked for an altitude change. I received a lower altitude of 4000', which was at the base of the clouds. I was having trouble holding that altitude due to the weight of the ice and the altered airfoil. The pitot was iced closed and perhaps the static air port was frozen shut as well. My airspeed dropped to 0 due to the closed pitot, and my altimeter was unreliable as a result. I was now in a valley, and was attempting to stay at 4000', but was having extreme difficulty doing so. Center also informed me that communications were fading due to my altitude and position. Below 4000', I was in VFR conditions with good visibility. I called ipt tower and informed them that I had lost communications with center and was on an IFR flight plan. They suggested that I try to reestablish contact and I successfully regained communication. At this time, being in VFR conditions and warmer air, the ice had melted and the runway environment was in sight. There was a tall communications tower along my flight path and I skirted it with no problem. Upon landing, I was asked to call center and did so. I deviated from the designated altitude of 4000' due to airframe failure due to icing, unreliable instrument readings, and a brief communications blackout. I did not willfully or intentionally violate an order from center.

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Original NASA ASRS Text

Title: GA SMA PLT DESCENDED INTO ICING CONDITIONS, LOST AIRSPEED AND ALTIMETER AND WAS UNABLE TO MAINTAIN CLRNC ALT.

Narrative: I WAS GIVEN AN ALT CHANGE FROM 8000 TO 6000' AT MY DISCRETION. I ELECTED TO COMPLY IMMEDIATELY. THIS NEW ALT PLACED ME IN A CLOUD FORMATION WITH MODERATE TURB. I WAS IMMEDIATELY ICED OVER WITH A HEAVY LAYER OF CLEAR ICE. THE WINDSHIELD, AS WELL AS THE WINGS, STABILIZERS AND CONTROL SURFACES WERE IMMEDIATELY ENCRUSTED. I RPTED MY CONDITIONS AND ASKED FOR AN ALT CHANGE. I RECEIVED A LOWER ALT OF 4000', WHICH WAS AT THE BASE OF THE CLOUDS. I WAS HAVING TROUBLE HOLDING THAT ALT DUE TO THE WEIGHT OF THE ICE AND THE ALTERED AIRFOIL. THE PITOT WAS ICED CLOSED AND PERHAPS THE STATIC AIR PORT WAS FROZEN SHUT AS WELL. MY AIRSPD DROPPED TO 0 DUE TO THE CLOSED PITOT, AND MY ALTIMETER WAS UNRELIABLE AS A RESULT. I WAS NOW IN A VALLEY, AND WAS ATTEMPTING TO STAY AT 4000', BUT WAS HAVING EXTREME DIFFICULTY DOING SO. CENTER ALSO INFORMED ME THAT COMS WERE FADING DUE TO MY ALT AND POS. BELOW 4000', I WAS IN VFR CONDITIONS WITH GOOD VISIBILITY. I CALLED IPT TWR AND INFORMED THEM THAT I HAD LOST COMS WITH CENTER AND WAS ON AN IFR FLT PLAN. THEY SUGGESTED THAT I TRY TO REESTABLISH CONTACT AND I SUCCESSFULLY REGAINED COM. AT THIS TIME, BEING IN VFR CONDITIONS AND WARMER AIR, THE ICE HAD MELTED AND THE RWY ENVIRONMENT WAS IN SIGHT. THERE WAS A TALL COMS TWR ALONG MY FLT PATH AND I SKIRTED IT WITH NO PROB. UPON LNDG, I WAS ASKED TO CALL CENTER AND DID SO. I DEVIATED FROM THE DESIGNATED ALT OF 4000' DUE TO AIRFRAME FAILURE DUE TO ICING, UNRELIABLE INSTRUMENT READINGS, AND A BRIEF COMS BLACKOUT. I DID NOT WILLFULLY OR INTENTIONALLY VIOLATE AN ORDER FROM CENTER.

Data retrieved from NASA's ASRS site as of August 2007 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.