When is carburetor icing most likely to occur?

Carburetor icing is a phenomenon that can significantly affect engine performance in aircraft equipped with carbureted engines. The conditions under which carburetor icing is most likely to occur are typically when the air temperature is between -7 degrees Celsius (20 degrees Fahrenheit) and 21 degrees Celsius (70 degrees Fahrenheit), accompanied by visible moisture or high humidity.

In this temperature range, the air is cool enough for ice to form, and the presence of moisture—such as in the form of fog, rain, or high humidity—provides the necessary water vapor that can condense and freeze within the carburetor. When air enters the carburetor, it expands and cools, which can further contribute to icing. This combination of cool temperatures and moisture creates ideal conditions for the formation of ice within the carburetor, potentially leading to a reduction in engine power or even engine failure if not managed properly.

The other scenarios listed do not create the right combination of temperature and humidity for carburetor icing to occur. High temperatures, dry conditions, or high altitudes without moisture do not support the development of icing in the carburetor. Understanding these conditions is crucial for pilots to ensure safe operation and proper engine performance during flight.