What should controllers transmit to contribute to air traffic control?

Controllers play a vital role in maintaining safe and efficient air traffic operations. They are responsible for transmitting messages that are critical for air traffic management and safety. The correct answer emphasizes the importance of sending messages that are necessary and contribute to the overall safety of air traffic control.

When controllers transmit messages that are essential, they help ensure that pilots receive information about their flight paths, altitude changes, and any potential hazards in their vicinity. This communication is a key component in preventing accidents and enabling smooth operations in the airspace.

Focusing solely on emergency messages, as suggested in one of the choices, would fail to address the routine yet critical communications necessary for daily operations. Operational communications encompass a wider range of scenarios, including routine updates and instructions that contribute to an aircraft's safe journey through progressively busy air traffic environments.

In contrast, transmitting general information about other aircraft may not be sufficient since it lacks the directed nature required for effective air traffic control. It is essential that the messages shared are relevant and actionable for maintaining safety and efficiency in airspace management.