Dead air: what it is and how radio stations prevent it

Dead air is silence nobody planned: "a period of silence during a radio or television broadcast that is not intended", in the Cambridge Dictionary's words. On an internet station it is easy to miss, because the stream usually stays up: the player connects, its timer counts, and no sound comes out. It is also common. Of the 634 streams our monitoring watched in the 90 days to October 30, 2026, 330 (52%) were flagged for dead air at least once, 5,338 times in all, and half of those silences lasted 15 minutes or more. Those are our figures, and they include streams hosted elsewhere and silences a station meant to have.

This guide covers the station's side: the causes, the safeguards, the alerts and the log. For presenters, see what a presenter does when it goes silent.

The definition sets no length, so each station sets its own. A second between two songs isn't what anyone means, and neither is a pause for effect or a minute's silence the station announced. A song that ends with nothing after it is dead air, and so is a stream carrying a low, steady hum where the show should be. Broadcast engineers choose the threshold when they install a silence detector: Broadcast Tools' Silence Sentinel Basic G2, for one, raises its alarm when the level stays below a threshold of 20 to 35 dB under the reference for a delay they pick, from off to 5 minutes (Broadcast Tools).

Two recent cases from UK broadcasters show how it happens and how long it can last.

• On the night of January 3, 2025, a central technical failure hit BBC Local Radio during its networked late-night show, carried by 40 stations in England. Twenty minutes into the show the network went to dead air for 15 minutes, and most stations then carried a feed from BBC Radio 5 Live for the rest of the night (RadioToday, January 2025).
• On May 19, 2026, a Radio Caroline staff member doing maintenance played, by mistake, announcements recorded in advance for the day King Charles III dies, which falsely said he had died, and which cut off the remote presenter's stream. After them and the national anthem, DAB+ listeners heard 16 minutes of silence, while AM listeners heard back-up music. The station said its presenter "would not realise that they had gone 'off air' unless they were monitoring their output via an internet monitor" (BBC News, August 2026).

Broadcast stations use silence detectors, often with a switch to a backup built in. Broadcast Tools' Audio Sentinel +»Web/RJ watches two sources, "one primary, the other back-up", switches to the backup "when silence is detected on the primary input", and emails up to eight people (Broadcast Tools). Deva's DB8009-MPX adds its own MP3 backup, more than 24 hours without a repeat (Deva Broadcast).

The US rule we found, 47 CFR 73.1740, sets a commercial station's minimum operating hours. A station knocked off the air by causes beyond its control can stay off up to 30 days without FCC approval, notifying the FCC by the 10th day, and a licence expires after 12 months without transmitting (47 CFR 73.1740). It says nothing about minutes of silence, and it doesn't bind internet-only stations. An internet station needs the same two parts: a fallback that starts by itself and an alarm someone hears.

The first row is the easiest to cover: when an encoder disconnects, the server can move listeners to something else. Power cuts do it too: when a power cut hit central Bristol on September 5, 2025, BBC Radio Bristol's afternoon show went silent as the studio lost power, until a presenter at BBC Radio Somerset took the show over (RadioToday, September 2025).

The second row is the one a streaming server's fallback misses. A streaming server doesn't listen to the audio: to Icecast, an encoder sending silence is still sending audio data, and Icecast only drops a source that "does not send any data" for its source timeout (Icecast documentation). So the backup never starts, and the silence lasts until somebody notices.

Play the music from a server. If the station's music plays from a computer at home or in the studio, a crash, sleep or update restart silences the station. Windows 11, for example, is moving to one restart a month for updates, "outside of your active hours whenever possible" (Microsoft, August 2026), and a computer that plays around the clock has no quiet hours, so the restart takes the station off air. With automation on a server, the computer at home only matters while someone is live (keeping the station playing with your computer off).

Put a fallback under every live show. When a live source disconnects, something should start by itself. On an Icecast server you run yourself, that's a fallback mount: listeners move to it "if the source shuts down", and without one they're disconnected (Icecast documentation). A hosted AutoDJ does the same job.

Stop the encoder when your software freezes. A connected source that sends silence keeps the air (stays what listeners hear), on Icecast and on CloudRadio alike, because both only check that data arrives. Make it a station rule: if the playout program or mixer freezes, disconnect the encoder and let the fallback play. If you run your own Liquidsoap server, its cookbook shows how to make a silent live input step aside after a few seconds of silence (Liquidsoap).

Keep something to play at every hour. Automation can go silent when it runs out: a playlist that ends, a schedule with a hole in it, a music folder on a drive that isn't there. Read next week's schedule for gaps, and give the station a long default playlist, or background programming, for any hour without a show.

Check your files for long silences. A hidden track at the end of an album, a recorded show with a gap where an ad used to be, or an export with a minute of nothing at the end will air every second of that silence. Listen to new recordings to the end, or look at the waveform, before they go into rotation.

Test before every live show. A two-minute check before you go live catches the usual silent-input mistakes before listeners hear them:

1. Watch your encoder's level meter move when you talk and when music plays.
2. Once you're connected, listen to the station's stream on your phone. Your headphones play what your mixer sends; the stream plays what listeners hear, about 30 seconds later.
3. Know what plays if you disconnect (the Input priority list on the dashboard shows the order), how to disconnect quickly, and keep your phone where you'll see an alert. Once, when you set the station up, disconnect in the middle of a song and check that the fallback starts.

A check that only asks whether the stream answers sees only one of them.

To catch dead air, a monitor has to open the stream and decode the audio the way a listener's player does. It should do it from more than one place, because a check from a single network can't tell a stream that's down from a bad route between the two.

Send the alert to someone who can act on it at that hour. On October 30, 2026, 421 of the 634 streams our monitoring watched had the account holder's alerts on, so a third had them off. During a live show, the person who most needs to know is the presenter, and like Radio Caroline's, they can be the last to find out, because they hear their own mixer. On CloudRadio, booked DJs can't open Monitoring, so the owner or a station manager adds each presenter's email address as a recipient.

While the stream is down or silent, the Automatic Status Banner can put a red bar at the top of your website, with a default message or one you write on the monitor page, so visitors who hear nothing know you're on it.

Write down every silence while you still remember it: when it started and ended, what was on air, who was on, the cause, and what you changed. A few weeks of entries show patterns that a single alert can't. Look for repeats: the same hour on several days points to a timer (an overnight restart, a scheduled show with an empty playlist); the start of live shows points to how presenters connect; new uploads point to the files.

There's no fixed length. Broadcast silence detectors let the engineer choose the delay, from a few seconds to several minutes. On CloudRadio, the alert goes out 2 to 3 minutes into a silence, after three silent checks a minute apart.

Yes. Say before and after that it is deliberate, so listeners don't think the stream has failed. On CloudRadio, a minute of silence ends before the third check and raises no alert. For a longer planned silence or maintenance, use Pause alerts on the monitor page, for 1, 2 or 4 hours; checks keep running and incidents are still recorded (pausing alerts for maintenance).

CloudRadio One plays your station from our servers, takes over when a live show drops, and checks your stream for dead air from four locations, with unlimited listeners, for $39/month.