What does "CAT" mean in CAT I and CAT II approaches?

"CAT" in the context of CAT I and CAT II approaches stands for "Category." This terminology indicates the complexity and precision requirements of the different types of instrument approaches. Each category (I, II, III) corresponds to specific criteria related to weather minimums, equipment requirements, and operational procedures.

Category I approaches generally allow for operations down to a decision height of 200 feet above ground level and visibility minimums of 1,800 feet or 550 meters. As the categories progress to II and III, the visibility and decision height requirements decrease, allowing for approaches in poorer weather conditions. This classification is critical for pilots to ensure that they are using the appropriate procedures and equipment according to the specific conditions they will be operating in.

The other options, while they may present relevant concepts in aviation, do not accurately capture the meaning of "CAT" as it pertains to these approaches. "Catastrophe," "Classification based on aircraft size," and "Calibration" do not describe the systematic categorization of approaches based on their operational requirements. Understanding "Category" in this context helps pilots recognize the operational parameters needed for safe landings under varying conditions.