Which of the following correctly defines the term 'air traffic'?

The term 'air traffic' encompasses all civilian aircraft operations, both on the ground and in the air. This includes the operations of passenger airlines, cargo flights, and other civilian aviation activities that take place in controlled airspace and at airports. Understanding air traffic is essential for ensuring safety, efficiency, and coordination among various types of aircraft operating within shared airspace.

This definition acknowledges the complexity of airspace management, where multiple aircraft, each with specific routes and purposes, must be managed to avoid collisions and inefficiencies. The reference to operations on the ground also highlights the coordination necessary during takeoff, landing, and taxiing at airports.

By contrast, the other options focus on more limited scopes—commercial flights, military operations, or international flights—none of which capture the full breadth of what constitutes air traffic in a comprehensive and practical sense. Therefore, defining air traffic as encompassing all civilian aircraft operations provides a complete understanding of its implications in aviation.