In air traffic control, what does 'CST' signify when shown in the data block?

In air traffic control, 'CST' in the data block signifies a specific type of coordination or status related to the aircraft. This abbreviation can be important in understanding the operational context of the flight. For instance, it may indicate that the aircraft is in a certain phase of its flight, or that specific coordination has taken place with respect to the flight's route or altitude assignments.

Recognizing this is crucial for air traffic controllers, as it helps ensure that all personnel are aware of the current status and any special requirements or procedures that need to be followed for the aircraft in question. Understanding these indicators facilitates better communication and efficiency in airspace management, contributing to overall flight safety.