Which factor is most critical to monitor during the de-icing process?

Monitoring the temperature of the aircraft surfaces is crucial during the de-icing process because the effectiveness of de-icing fluids is highly dependent on the temperature. If the aircraft surfaces are too cold, the de-icing fluid may not properly remove ice, snow, or frost, as these contaminants can bond to the surface and become more difficult to remove. Additionally, if the surface temperature is below the freezing point, even recently applied de-icing fluids might freeze prematurely, failing to provide the necessary protection before takeoff.

Optimal surface temperatures ensure that the de-icing fluid is applied effectively, allowing it to work as intended to clear the aircraft before it takes flight. This is especially vital because any residual ice or contaminants can significantly impact the aircraft's performance, safety, and ability to operate efficiently. Understanding and monitoring this temperature helps ensure safe operations in winter weather conditions.