Air traffic services

Air traffic services are the ground based services that support flights with control, information, alerting, and related functions. You use them before and during flight to obtain clearances, traffic information, flight information, and help in abnormal or emergency situations. Different ATS units such as tower, approach, area control, or flight information service may provide different parts of the service. As a pilot, you contact the appropriate unit on the correct frequency, follow its instructions when applicable, and keep it informed of your intentions and flight progress.