What kind of communication does SELCAL allow for with aircraft?

SELCAL, which stands for Selective Calling, is a system designed to allow air traffic control and ground stations to alert aircraft without the need for continuous monitoring of audio frequencies by the pilots. When a ground station or air traffic control wants to communicate with a specific aircraft, they can send a unique SELCAL code which the aircraft's system recognizes. This alerts the crew to the fact that they have an incoming message, prompting them to switch their focus to the relevant communication channel at that moment.

This system is particularly beneficial because it helps reduce the workload for pilots, allowing them to concentrate on flying and monitoring their instruments without the constant distraction of radio traffic. Although pilots will still need to respond verbally once they are alerted, the initial call does not require them to monitor the frequency actively. This capability distinguishes SELCAL from direct voice communications, text messaging, and emergency broadcasts, as it specifically allows for prompt communication with minimal distraction.