What distinguishes de-icing from anti-icing?

The distinction between de-icing and anti-icing is fundamentally about their respective purposes in relation to ice on surfaces, particularly in aviation.

De-icing specifically refers to the process of removing existing ice or snow from an aircraft's surfaces to ensure safe operation. This process is crucial immediately before takeoff or during snow and ice conditions to eliminate any present ice that could affect aircraft performance, adherence to regulations, or safety in flight.

On the other hand, anti-icing involves applying certain fluids or treatments that prevent ice or snow from bonding to surfaces in the first place. This technique is aimed at maintaining surfaces in a state that will not allow ice to accumulate, thus providing an added layer of protection rather than just reacting to existing conditions.

This understanding clarifies why the correct answer emphasizes the removal of existing ice with de-icing while highlighting that anti-icing is about preventing future accumulation. Recognizing this difference is essential for effective winter operations, especially in aviation.