What is the primary source of information for an ATC clearance?

The primary source of information for an ATC (Air Traffic Control) clearance is current air traffic information. This encompasses real-time data about traffic conditions, weather, and any active restrictions or advisories that may affect flight operations. ATC ensures safety and efficiency in the airspace by using this dynamic information to issue clearances that guide aircraft during different phases of flight.

While ATIS reports provide important weather and operational information to pilots, they are generally not the primary basis for clearance. Flight plans submitted are essential for planning and coordination but do not reflect real-time conditions, thus they are not the sole source for issuing clearances. Standard operating procedures provide guidelines for operations but do not contain the specifics of current air traffic situations that influence clearances. Therefore, current air traffic information is crucial for ensuring that ATC clearances reflect the latest operational environment.