Narrative:

We were cruising at 6;000 ft when we entered the tops of the clouds and picked up trace icing and light turbulence. We were just in the tops and it appeared we could easily get on top; so we climbed to 8;000 ft to try to get clear of the layer and find some smooth air. At 8;000 ft; we were still in the clouds and began picking up light clear icing. At this point I tried the boots; just to ensure they were still working; in case the icing got worse. (They had tested fine on the ground that morning) the sfc deice light would not illuminate and the wing boots would not visually inflate. (During the rest of the flight; I continued to attempt to blow the boots; followed by a reset; and repeated this continually throughout the flight.) we asked for a climb to 10;000 ft to get out of icing conditions; believing that we would easily top the layer by then. However; the tops were rising with us; and after being level at 10;000 ft for a few minutes we were still in the layer and began picking up moderate clear icing. We were approaching our destination so we asked for; and were cleared to descend. I was hoping the descent would allow the ice to melt off; however during the first 500 ft of the descent we began picking up a significant amount of clear ice. At this point the copilot voiced his concern that the aircraft was beginning to handle sluggishly and that he was concerned about the amount of ice on the aircraft; so I rechecked the weather and noticed that it was now freezing on the surface; making the descent useless. I then called center asking to abandon the approach and asked for a PIREP about the cloud tops. Center believed we would top out at 11;000 ft so I asked for a climb to that altitude; since it was only about 1;500 ft away. The copilot began a full power climb at this point. During this entire time the aircraft was still accumulating ice and was unable to shed it. The aircraft was unable to maintain a positive rate of climb at 120 knots and full power; so I called center and told them we were unable to climb and asked for a 180 degree turn and a descent to the lowest altitude he could give us. We rapidly descended to 6;400 ft; and after getting the ATIS in ZZZ; decided to divert there; mainly because it was close and the temperature on the surface was above freezing. Once we got within 30 miles or so of ZZZ; passing through about 8;000 ft; I managed to get the boots activated; and the aircraft shed the ice. Passing through 7;000 ft; the ice also began to melt off of the windshield and the rest of the aircraft. We completed the approach and landing with no further ice accumulation.initially; we were not picking up enough ice for me to be concerned that the boots were not working. I had been in and out of this airport prior to this flight and had only picked up a trace of clear ice in cruise at 8;000 ft and I was able to get on top at 10;000 ft; and whatever traces of ice I had accumulated quickly melted off during my descent on the approach. During my weather briefing; I noticed that the group of low pressure areas were still grouped over the area; and there were multiple warm and cold fronts noted on the chart; but it did not appear the I would be crossing the cold front that I ended up crossing. I believe that sometime between my weather briefing and my arrival into the area; the low pressures began to consolidate and a definite cold front developed across my route of flight; bringing with it a lot more moisture than I thought and much lower temperatures. Once we crossed the cold front and began to encounter the moderate and severe icing; I did have an escape plan; however it was an escape plan that was better suited to the turboprops I used to fly.

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Original NASA ASRS Text

Title: Captain of Cessna twin encountered unexpected icing conditions and discovers the wing deice boots were not functioning. Attempts to climb above the weather are unsuccessful; the flight diverted to a warmer airport. The wing boots began to work and the windshield ice begins to melt during descent.

Narrative: We were cruising at 6;000 FT when we entered the tops of the clouds and picked up trace icing and light turbulence. We were just in the tops and it appeared we could easily get on top; so we climbed to 8;000 FT to try to get clear of the layer and find some smooth air. At 8;000 FT; we were still in the clouds and began picking up light clear icing. At this point I tried the boots; just to ensure they were still working; in case the icing got worse. (They had tested fine on the ground that morning) The SFC DEICE light would not illuminate and the wing boots would not visually inflate. (During the rest of the flight; I continued to attempt to blow the boots; followed by a reset; and repeated this continually throughout the flight.) We asked for a climb to 10;000 FT to get out of icing conditions; believing that we would easily top the layer by then. However; the tops were rising with us; and after being level at 10;000 FT for a few minutes we were still in the layer and began picking up moderate clear icing. We were approaching our destination so we asked for; and were cleared to descend. I was hoping the descent would allow the ice to melt off; however during the first 500 FT of the descent we began picking up a significant amount of clear ice. At this point the Copilot voiced his concern that the aircraft was beginning to handle sluggishly and that he was concerned about the amount of ice on the aircraft; so I rechecked the weather and noticed that it was now freezing on the surface; making the descent useless. I then called Center asking to abandon the approach and asked for a PIREP about the cloud tops. Center believed we would top out at 11;000 FT so I asked for a climb to that altitude; since it was only about 1;500 FT away. The copilot began a full power climb at this point. During this entire time the aircraft was still accumulating ice and was unable to shed it. The aircraft was unable to maintain a positive rate of climb at 120 knots and full power; so I called Center and told them we were unable to climb and asked for a 180 degree turn and a descent to the lowest altitude he could give us. We rapidly descended to 6;400 FT; and after getting the ATIS in ZZZ; decided to divert there; mainly because it was close and the temperature on the surface was above freezing. Once we got within 30 miles or so of ZZZ; passing through about 8;000 FT; I managed to get the boots activated; and the aircraft shed the ice. Passing through 7;000 FT; the ice also began to melt off of the windshield and the rest of the aircraft. We completed the approach and landing with no further ice accumulation.Initially; we were not picking up enough ice for me to be concerned that the boots were not working. I had been in and out of this airport prior to this flight and had only picked up a trace of clear ice in cruise at 8;000 FT and I was able to get on top at 10;000 FT; and whatever traces of ice I had accumulated quickly melted off during my descent on the approach. During my weather briefing; I noticed that the group of low pressure areas were still grouped over the area; and there were multiple warm and cold fronts noted on the chart; but it did not appear the I would be crossing the cold front that I ended up crossing. I believe that sometime between my weather briefing and my arrival into the area; the low pressures began to consolidate and a definite cold front developed across my route of flight; bringing with it a lot more moisture than I thought and much lower temperatures. Once we crossed the cold front and began to encounter the moderate and severe icing; I did have an escape plan; however it was an escape plan that was better suited to the turboprops I used to fly.

Data retrieved from NASA's ASRS site as of April 2012 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.