What does "de-icing" refer to in airport operations?

De-icing in airport operations is specifically related to the removal of snow or ice from an aircraft. This is a critical safety measure that ensures the aircraft's surfaces, such as the wings and tail, are free from ice, which can adversely affect lift and overall aircraft performance during takeoff and landing. Proper de-icing is vital for maintaining control of the aircraft and preventing accidents in winter weather conditions when ice and snow are prevalent.

This process typically involves the use of heated fluids that are sprayed onto the aircraft to melt and remove ice and snow. The effectiveness of de-icing directly impacts the safety of flight operations, making it a crucial procedure in the airport's operational protocols, especially in cold weather climates.

The other options, while related to airport operations, do not accurately define de-icing. For instance, the application of anti-skid substances to runways pertains to runway safety during icy conditions but does not involve the aircraft itself. Evaluating aircraft weight before takeoff is part of preflight checks and safety assessments but is not related to de-icing. Finally, coating aircraft for aerodynamic efficiency involves aspects of aircraft maintenance and design, rather than the immediate concerns related to ice removal.