EnglsihmaninNY..
Not an expert on this by any means, and as I'm in a public libary I don't have access to any literature, but it does make sense.
You've probaly seen those graphs (CAA Saftey Sense leaflet on Carb Ice, FAA must have them too) which shows that Carb Ice can accure up to 25C. Obviously very cold air has less moisture so is less able to form ice, therefor it does stand to reason that introducing warm air could bring it into the risk area.
Incidently, back in 1998, when I had around 60 hours TT, I was hours building out in Southern California when I suffered Carb Icing. I had been taught to apply carb heat every 10 mins or so for around 10 seconds. No-one had told me what the symtons of carb icing actually were. I knew that with carb icing when one applied heat the engine got worse as the ice turned to water...When the engine started to run rough (I was over the Pacific at the time, planning to fly around an island 10nm out from the mainland) I applied carb heat for what seemed like a long time, but in my, er elevated state of awareness it was probably only 2-3 seconds. Nothing happened. Not better, not worse. As my Dad had taught me about the process of elimination, I assumed it wasn't carb ice..
Anyway, I did get back safely, a somewhat older and more experienced pilot than the 21 year 60 hour PPL who had taken off. My point is, those standard, robotic applications of carb-heat might not be enough (and I had just leveled off at TOC) and when Carb Ice does appear, it might take a long application of heat to clear it.
I've only once since then (now got over 1000 hours, all piston) had carb ice worse than that, in a Pawnee when it was getting icing even at full power!
Last edited by Jump Complete; 13th Dec 2002 at 18:31.