Understanding Carburettor Icing: A Vital Aspect for Pilots

Carburettor icing presents a significant risk to aircraft operation, particularly for piston-engine aircraft. Let’s delve into what carburettor icing is, why it occurs, and how pilots can mitigate its effects to ensure safe flights.

What is Carburettor Icing?

The carburettor is a crucial component of a piston engine, where air mixes with fuel before entering the engine cylinders. During this mixing process, fuel evaporation and air pressure reduction cause a significant temperature drop inside the carburettor. If the air temperature inside the carburettor drops below the dew point temperature, ice will form on its walls, leading to restricted fuel/air mixture flow and potential engine power loss or failure.

Factors Contributing to Carburettor Icing:

  • Temperature Drop: A temperature decrease of 25°C to 30°C inside the carburettor is common, even if the outside air temperature is above freezing.
  • Humidity: Warm, humid conditions increase the risk of carburettor icing, as warm air can hold more moisture.
  • Low Power Settings: At low power settings, the throttle valve restricts airflow into the engine, exacerbating the temperature reduction and icing risk.

Detection and Prevention:

  • Carburettor Heat: Applying carburettor heat can quickly melt ice buildup, restoring engine performance. However, expect temporary engine roughness as the ice melts and water flows through the engine.
  • Awareness: Pilots should remain vigilant for carburettor icing, even on warm days with high humidity, where icing risk is heightened.
  • Risk Assessment: Familiarize yourself with carburettor icing risk graphs, which depict the likelihood of icing based on temperature and dew point.

Beyond Carburettor Icing:

  • Engine Intake Icing: Flight in icing conditions can lead to ice formation on the airframe and engine air intake, reducing engine power and potentially causing engine failure.
  • Propeller Icing: Ice formation on propeller blades can cause severe vibration and reduce thrust, posing a safety hazard during flight.


Carburettor icing, along with other forms of icing, presents significant challenges to aircraft operation. By understanding the factors contributing to icing, implementing preventive measures, and maintaining situational awareness, pilots can effectively mitigate risks and ensure safer flights. Always prioritize safety and be prepared to take appropriate actions when encountering icing conditions during flight.

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