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Old 4th Jan 2010, 19:00
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IO540
 
Join Date: Jun 2003
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NO - carb heat is nothing to do with low outside temp. Carb heat is what you use to safeguard against (or melt) the ice in the carb venturi which is caused by the temperature drop in the venturi, and in the right conditions (humid, not too cold, not too hot) this can otherwise cause an ice buildup. Loads of stuff online e.g. this.

Low outside temps are a hazard for structural (airframe) icing. This is not an issue if you stick to clear VMC, but for flight in IMC you have a problem in that any ice you pick up [cue the usual dire warnings about icing and death] you will be landing with, and if you picked up a lot, then your landing speed has to be so much higher to maintain control... basically if the 0C level is below the MSA then you have cut off the obvious escape route from structural icing; not a good idea.

The other issue is ground icing (frost) which does need to be cleaned off pretty well before flight.
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