Narrative:

First; this is just a general report as I have had several encounters with icing conditions. I am based in ZZZ and have been doing mountain flying in a dash 8-200 model for several years and just wanted to submit a report on things I have learned from icing encounters in the dash 8. I have 3 events in my career that I think were a situation I now see as severe icing encounters. In all 3 events; they were at -8 degrees C or 18 degrees F. This is the magic temperature. We started picking up super cooled large droplets or as I call it huge water drops which go beyond a foot after contact before they freeze on the windshield. If it goes farther; then it is getting behind our deicing equipment in my experience. Every time I have seen -8 degrees C and clear ice I had gotten an inch of ice within a minute and also every time requested lower right away. The worst time was where it accumulated at more than 2 inches within the first minute. I lost my windshield completely; put the props to 1200 RPM and told my first officer who was also a newer captain flying right seat at the time we needed lower as soon as possible! We were on vectors and within that first minute we had so much ice on us we had lost 15 KTS which is not normally something the dash does at all in icing. I knew we could not climb out of it in time; so when ATC gave us lower I had the autopilot off and dove down at 3;000-4;000 FPM to 16;000 ft to get out of that temperature of -8 degrees C. At 16;000 ft we were still picking up light rime but it was +3 degrees C and not a concern anymore. However; that minute and a half or so at -8 degrees C and in super cooled large droplet conditions had dumped so much ice on the plane I could barely see out my left window at the boots and prop hub. They were loaded with ice. I felt the plane was limping along. The plane was shaking violently with all the ice on the props. I had had the ice systems on maximum the entire flight. We finally broke out of IMC and ZZZ wanted us to call the airport in sight; but I told them we needed to fly for a bit and get lower to melt all the ice as I couldn't see out my window to land. We got lower yet and by -2 to -1 degrees C the ice started breaking off and melting. We finally got cleared for the visual but by the time I started to configure for landing we had melted all the ice. In the other 2 events that I had they were similar. Ever since then I have watched very closely to make sure we are not getting clear ice at -8 degrees C. The temperature and clear ice combination has always led to severe icing conditions. If it is rime at -8 degrees C I am fine; but the moment I see ice more than 1 foot up from the bottom of my windshield and its clear ice; I know I have to get out of it. In my experience; if you lose your windshield in the dash; you are getting way too much ice and it is getting behind the deice equipment. The only time I have ever lost my windshield was when it is clear at -8 degrees C and all were around the 15;000 to FL200 level. Those have been the only times and all 3 times were bad. Again; the only times I have seen it go farther than a foot back is in this exact condition. Clear ice (super cooled large droplets) drops at -8 degrees C. I can't stress that temperature enough! I have encountered clear ice at other temperatures and it just doesn't accumulate much. However at -8 degrees C it accumulates so fast you barely have enough time to get out of it and I have learned you can't climb because you pick up so much weight and lose airspeed the plane won't climb in time to get out of it. I have read about super cooled large droplet icing and that is how I now know I got that in those events.

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Original NASA ASRS Text

Title: Dash-8-200 Captain recounts past icing experiences with super cooled large droplets that he feels may be germane to current events.

Narrative: First; this is just a general report as I have had several encounters with icing conditions. I am based in ZZZ and have been doing mountain flying in a Dash 8-200 model for several years and just wanted to submit a report on things I have learned from icing encounters in the Dash 8. I have 3 events in my career that I think were a situation I now see as severe icing encounters. In all 3 events; they were at -8 degrees C or 18 degrees F. This is the magic temperature. We started picking up Super Cooled Large Droplets or as I call it huge water drops which go beyond a foot after contact before they freeze on the windshield. If it goes farther; then it is getting behind our deicing equipment in my experience. Every time I have seen -8 degrees C and clear ice I had gotten an inch of ice within a minute and also every time requested lower right away. The worst time was where it accumulated at more than 2 inches within the first minute. I lost my windshield completely; put the props to 1200 RPM and told my First Officer who was also a newer Captain flying right seat at the time we needed lower as soon as possible! We were on vectors and within that first minute we had so much ice on us we had lost 15 KTS which is not normally something the Dash does at all in icing. I knew we could not climb out of it in time; so when ATC gave us lower I had the autopilot off and dove down at 3;000-4;000 FPM to 16;000 FT to get out of that temperature of -8 degrees C. At 16;000 FT we were still picking up light rime but it was +3 degrees C and not a concern anymore. However; that minute and a half or so at -8 degrees C and in Super Cooled Large Droplet conditions had dumped so much ice on the plane I could barely see out my left window at the boots and prop hub. They were loaded with ice. I felt the plane was limping along. The plane was shaking violently with all the ice on the props. I had had the ice systems on maximum the entire flight. We finally broke out of IMC and ZZZ wanted us to call the airport in sight; but I told them we needed to fly for a bit and get lower to melt all the ice as I couldn't see out my window to land. We got lower yet and by -2 to -1 degrees C the ice started breaking off and melting. We finally got cleared for the visual but by the time I started to configure for landing we had melted all the ice. In the other 2 events that I had they were similar. Ever since then I have watched very closely to make sure we are not getting clear ice at -8 degrees C. The temperature and clear ice combination has always led to severe icing conditions. If it is rime at -8 degrees C I am fine; but the moment I see ice more than 1 foot up from the bottom of my windshield and its clear ice; I know I have to get out of it. In my experience; if you lose your windshield in the Dash; you are getting way too much ice and it is getting behind the deice equipment. The only time I have ever lost my windshield was when it is clear at -8 degrees C and all were around the 15;000 to FL200 level. Those have been the only times and all 3 times were bad. Again; the only times I have seen it go farther than a foot back is in this exact condition. Clear ice (Super Cooled Large Droplets) drops at -8 degrees C. I can't stress that temperature enough! I have encountered clear ice at other temperatures and it just doesn't accumulate much. However at -8 degrees C it accumulates so fast you barely have enough time to get out of it and I have learned you can't climb because you pick up so much weight and lose airspeed the plane won't climb in time to get out of it. I have read about Super Cooled Large Droplet icing and that is how I now know I got that in those events.

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.