What aspect of airport operations does the term "turnaround" refer to?

The term "turnaround" in airport operations specifically refers to the duration required for an aircraft to be ready for its next flight. This encompasses all activities that must be completed between the aircraft's arrival and its subsequent departure, including unloading passengers, baggage handling, refueling, cleaning, and boarding new passengers. Efficient turnaround processes are critical for maintaining an airline's schedule and improving operational efficiency, as delays in this phase can lead to missed flight schedules and impact overall airport operations.

The other options do not capture the full scope of what "turnaround" entails. For instance, while check-in times and baggage waiting periods are related to passenger processing and customer experience, they are not directly related to the aircraft's operational readiness. Additionally, unloading baggage is just one component of the broader turnaround process and does not reflect the complete timeline needed for preparing the aircraft for its next journey.