What must ATCOs do concerning flights entering their airspace?

Air Traffic Control Officers (ATCOs) have a critical role in managing the safe and efficient movement of aircraft within designated airspace. When it comes to flights entering their airspace, ATCOs must receive detailed information about any flight intending to transit through. This includes data such as the aircraft's identification, type, intended route, altitude, and any specific intentions or requests from the pilot.

This process is crucial for several reasons. First, it allows ATCOs to ensure that there is a clear understanding of the flight's intentions, enabling them to maintain safe separation from other aircraft. Second, having comprehensive information about incoming flights helps in planning and coordinating air traffic flow, which is essential for maintaining safety and efficiency within busy airspace. Therefore, option C highlights the fundamental responsibility of ATCOs in ensuring they are informed about flights entering their airspace, making it the correct answer.

The other choices, while they may touch on aspects of aviation operations, do not encapsulate the primary duty of ATCOs related to incoming flights. Logging flight times, conducting security checks, or scheduling airshows does not address the critical need for situational awareness and traffic management that comes with knowing the details of flights entering their airspace.