Dead air, also known as unmodulated carrier,[citation needed] is an unintended period of silence that interrupts a broadcast during which no audio or video program material is transmitted.
[1] Dead air occurs in radio broadcasting when no audio program is transmitted for an extended period of time, usually more than a few seconds.
[9][7] In the U.S., prolonged dead air, such as a shutdown occurring without permission, is an actionable offense that can result in fines from the Federal Communications Commission (FCC).
In the event of dead air lasting more than an acceptable duration, e.g. ≤ −70 dB and (if applicable) static/no picture for 30 seconds, an emergency program is cued.
[citation needed] Apart from providing a safeguard in the event of unscheduled interruption (like a fire in the building or technical issues), this mechanism may be used deliberately during programmed blackouts caused by strikes of technicians, journalists, and producers.
When staff of the French public broadcasting network Radio France went on strike in September 2020, a pretaped message informing listeners that no service is available due to industrial action was inserted into the loop.