Narrative:

Had in person briefing at north.Y. FSS for IFR trip isp to alb. No PIREPS of icing, but usual chance of icing in clouds. Isp was still reporting IFR, but was actually VFR. Destination was VFR with VFR forecast. Cold front to east of route moving eastward. Departed IFR then cancelled at 5000'. Increasing cloud cover below gradually forced me to 9500' MSL, 60 mi from alb. Alb ATIS reported 4500' broken. Asked for IFR descent, denied. Then received IFR clearance to alb. Minor error in clearance corrected shortly. By the time I received correct clearance I was just entering clouds and beginning descent to 7000'. After approximately 2 mins I encounter extremely rapid buildup of airframe ice--3/4' in just a few seconds. I have encountered ice approximately 8 times in the past, but never seen such a deadly buildup--almost instantaneous. I immediately began a left turn to opp heading and at same time told ATC of problem. Turbulence was strong in clouds and altitude control was difficult. I increased turn rate beyond standard because it appeared to me every second was critical. ATC was rather upset with me for turning before asking and waiting for permission. That is why I am reporting this. Although it is not his responsibility to report en route WX, he had to have something showing on his scope and could have alerted me of what was ahead. After all, he had time to chastise me. After the 180 degree turn, icing stopped with about 1 1/2' of ice on leading edge. Emerged from clouds and made VFR descent eastward, then westward, then returned to isp. Temperature at altitude was -20 degrees C. Windshield covered in 1-2 seconds with liquid rolling back then freezing. Ice on wings appeared mixed. I believe ice was from supercooled drops freezing on contact with aircraft. Everything happened fast. Transition from VFR to IFR and severe icing and turbulence resulted in poor aircraft control. Could have been much worse.

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Original NASA ASRS Text

Title: PLT OF SMA ENROUTE ISP TO ALB ENCOUNTERS SEVERE AIRFRAME ICING DURING IFR DESCENT.

Narrative: HAD IN PERSON BRIEFING AT N.Y. FSS FOR IFR TRIP ISP TO ALB. NO PIREPS OF ICING, BUT USUAL CHANCE OF ICING IN CLOUDS. ISP WAS STILL RPTING IFR, BUT WAS ACTUALLY VFR. DEST WAS VFR WITH VFR FORECAST. COLD FRONT TO E OF RTE MOVING EASTWARD. DEPARTED IFR THEN CANCELLED AT 5000'. INCREASING CLOUD COVER BELOW GRADUALLY FORCED ME TO 9500' MSL, 60 MI FROM ALB. ALB ATIS RPTED 4500' BROKEN. ASKED FOR IFR DSCNT, DENIED. THEN RECEIVED IFR CLRNC TO ALB. MINOR ERROR IN CLRNC CORRECTED SHORTLY. BY THE TIME I RECEIVED CORRECT CLRNC I WAS JUST ENTERING CLOUDS AND BEGINNING DSCNT TO 7000'. AFTER APPROX 2 MINS I ENCOUNTER EXTREMELY RAPID BUILDUP OF AIRFRAME ICE--3/4' IN JUST A FEW SECS. I HAVE ENCOUNTERED ICE APPROX 8 TIMES IN THE PAST, BUT NEVER SEEN SUCH A DEADLY BUILDUP--ALMOST INSTANTANEOUS. I IMMEDIATELY BEGAN A LEFT TURN TO OPP HDG AND AT SAME TIME TOLD ATC OF PROB. TURB WAS STRONG IN CLOUDS AND ALT CONTROL WAS DIFFICULT. I INCREASED TURN RATE BEYOND STANDARD BECAUSE IT APPEARED TO ME EVERY SECOND WAS CRITICAL. ATC WAS RATHER UPSET WITH ME FOR TURNING BEFORE ASKING AND WAITING FOR PERMISSION. THAT IS WHY I AM RPTING THIS. ALTHOUGH IT IS NOT HIS RESPONSIBILITY TO RPT ENRTE WX, HE HAD TO HAVE SOMETHING SHOWING ON HIS SCOPE AND COULD HAVE ALERTED ME OF WHAT WAS AHEAD. AFTER ALL, HE HAD TIME TO CHASTISE ME. AFTER THE 180 DEG TURN, ICING STOPPED WITH ABOUT 1 1/2' OF ICE ON LEADING EDGE. EMERGED FROM CLOUDS AND MADE VFR DSCNT EASTWARD, THEN WESTWARD, THEN RETURNED TO ISP. TEMP AT ALT WAS -20 DEGS C. WINDSHIELD COVERED IN 1-2 SECS WITH LIQUID ROLLING BACK THEN FREEZING. ICE ON WINGS APPEARED MIXED. I BELIEVE ICE WAS FROM SUPERCOOLED DROPS FREEZING ON CONTACT WITH ACFT. EVERYTHING HAPPENED FAST. TRANSITION FROM VFR TO IFR AND SEVERE ICING AND TURB RESULTED IN POOR ACFT CONTROL. COULD HAVE BEEN MUCH WORSE.

Data retrieved from NASA's ASRS site as of July 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.