From Longman Dictionary of Contemporary Englishbe on/off (the) airbe on/off (the) airTCBto be broadcasting on the radio or television at the present moment, or to stop broadcasting We’ll be on air in three minutes. → air
Examples from the Corpus
be on/off (the) air• The Channel 5 licence is expected to be awarded in early November and be on air at the latest in 1995.• We'll be on air in about three minutes.• Broadcasting via a system of street loudspeakers the radio is on the air for three hours each Sunday.• Ministers that were on the air selling prayer cloths.• Sue was talking as they went, describing the scene, and Kathleen realised they were on air live again.• They're under a lot of pressure because they have to be on air 24 hours.• Gillroy could no longer raise Darwin, and Koepang seemed to be off the air.• If left-wing radio talk show hosts got higher ratings, the right-wing hosts would be off the air.• By this standard, half the sitcoms would be off the air. 