What determines aircraft approach categories?

The correct answer is based on stall speed in landing configuration, which is the key parameter for determining an aircraft's approach category. The approach categories, defined by the FAA and other aviation authorities, are established to ensure safe separation between aircraft during approaches and landings, particularly in relation to air traffic control and instrument procedures.

The stall speed in landing configuration effectively reflects the speed at which an aircraft can safely maneuver during approach. This speed determines the aircraft's critical performance characteristics related to handling and stabilization as it descends towards the runway. Each approach category is tailored to ensure that appropriate separation distances are maintained to prevent wake turbulence and allow for safe landings, especially under low visibility conditions.

Other options like maximum landing weight, wingspan, and engine type do influence operational parameters and performance but do not define the approach category as precisely as stall speed does. For instance, while these factors can affect takeoff and landing distances, they do not determine the classification of flight maneuvers associated with safe approach speeds. The approach speed in cruise is unrelated, since the classification for landing operations is specifically concerned with stall characteristics during the critical phases of approach and landing.