FAA Commercial Pilot Airplane (CAX)WeatherHard
A pilot is flying at 8,000 feet MSL and notices the outside air temperature is +3°C, while the dew point is +2°C. The aircraft is flying through a layer of stratiform clouds. What type of icing, if any, would be most probable under these conditions?
- AMixed ice, due to the combination of above-freezing and near-freezing conditions.
- BNo structural icing, as the temperature is above freezing.
- CRime ice, due to the small temperature/dew point spread and stratiform clouds.
- DClear ice, due to the high temperature near freezing and stratiform clouds.
Show answer & explanationAnswer & explanation
Correct answer: B. No structural icing, as the temperature is above freezing.
Structural icing can only occur when there is visible moisture and the outside air temperature (OAT) is 0°C or colder. Since the OAT is +3°C, which is above freezing, any visible moisture (like the stratiform clouds) would be in liquid form and would not freeze upon impact with the aircraft. Therefore, no structural icing would occur.
Why the other options are wrong
- A. Mixed ice also requires temperatures at or below freezing.
- C. Rime ice requires temperatures at or below freezing (0°C).
- D. Clear ice requires temperatures at or below freezing (0°C).
Conditions for Structural Icing
For structural icing to form, two primary conditions must be met: visible moisture and an outside air temperature (OAT) at or below freezing (0°C).
- Visible moisture includes clouds, fog, rain, or drizzle.
- OAT of 0°C to -10°C often produces clear ice.
- OAT of -10°C to -20°C often produces rime ice.
Memory trick: Icing's a freeze, needs water and zero degrees.