What is the primary purpose of the Air Traffic Control Service (ATC)?

The primary purpose of the Air Traffic Control Service (ATC) is to prevent collisions and maintain an orderly flow of air traffic. This is achieved through various functions, including providing clear and accurate instructions to pilots, monitoring aircraft positions, and managing the safe spacing between aircraft both in the air and on the ground. This role is crucial to ensuring safety in the skies, as ATC coordinates the movements of numerous aircraft simultaneously, allowing for efficient and safe operations.

While the other choices mention important aspects of aviation, they do not reflect the core mission of ATC. Managing passenger bookings relates to airline operations and customer service, which is outside the scope of ATC's responsibilities. Facilitating aircraft maintenance checks pertains to safety and operational efficiency but occurs at the maintenance level, not within air traffic control services. Lastly, regulating airport facilities involves oversight of the physical infrastructure and services of airports, which is typically under the jurisdiction of airport authorities rather than ATC. Thus, the focus of ATC remains firmly on air traffic safety and efficiency.