General Authority of Civil Aviation (GACA) Aeronautical Information Publication (AIP) Practice Exam

Under what conditions do icing conditions exist?

1. Only at altitudes above 10,000 feet

2. When OAT is +10°C or below with visible moisture

3. When outside temperature is between 10°C and 20°C

4. Only during nighttime operations

The correct answer is: When OAT is +10°C or below with visible moisture

Icing conditions exist when the outside air temperature (OAT) is at +10°C or below in the presence of visible moisture. This condition is critical for flight safety because it allows for the formation of ice on aircraft surfaces, which can significantly affect aerodynamic performance and handling characteristics. Visible moisture can include clouds, fog, or precipitation, which can lead to water contact on colder surfaces of the aircraft, triggering ice accumulation. Temperature alone does not dictate icing conditions; rather, the combination of a low temperature and sufficient moisture is essential in this scenario. The other choices fail to address the key criteria of temperature and moisture that define icing conditions. For instance, icing can occur well below 10,000 feet or during the day, as long as the temperature and moisture requirements are met. This knowledge is crucial for pilots and flight operations to ensure they take appropriate precautions when flying in potentially icy environments.