The phrase "are on the air" means that a broadcast is currently happening or being transmitted. Other synonyms for this phrase include "live on air," "currently broadcasting," "on the waves," "airing now," "on the radio," "live streaming," and "currently airing." These phrases can all be used in a similar context to communicate that a program or broadcast is currently happening. Additionally, using alternate phrases can add a touch of variety and creativity to language, avoiding repetition and making communication more engaging for the listener. Overall, having a diverse set of synonyms for common phrases is always a useful tool for both writers and speakers to have at their disposal.