When should ATC issue traffic advisories to pilots?

ATC should issue traffic advisories to pilots whenever an aircraft is in proximity to another aircraft to ensure safety in the airspace. These traffic advisories provide pilots with critical information regarding nearby aircraft that could affect their flight path or safety. By informing pilots of nearby traffic, ATC plays an essential role in enhancing situational awareness, enabling pilots to maintain safe distances from other aircraft, and thus preventing potential collisions.

Issuing advisories solely during specific phases of flight like takeoff or landing would not address the dynamic nature of air traffic, where proximity can change rapidly at any time during flight. Advising during maintenance checks would not be relevant to active flying operations, just as traffic advisories post-landing are not typically needed since the aircraft is no longer in active flight. The essential function of traffic advisories is to maintain safety during all phases of flight when aircraft are in close quarters.