on duty

Idioms  

1. At one's post, at work, as in The new nurse was on duty that evening, or The watchman was fired because he was drunk on duty. [Mid-1600s] The antonym, off duty, means “not engaged in one's work,” as in Captain Smith was much more amiable when he was off duty. [Mid-1800s]

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Example Sentences

Other firefighters, the claim alleges, were on duty inside the building the entire time — apparently oblivious.

From Los Angeles Times • May 9, 2026

Bass ousted Fire Chief Kristin Crowley last year, saying she should have kept critical fire personnel on duty on the day the fire broke out.

From Los Angeles Times • May 6, 2026

A memorial to a police officer, whose death on duty led to tougher sentences for the killers of emergency workers, has been unveiled by his widow.

From BBC • Apr. 23, 2026

About 15 minutes after the collision, the controller is still on duty, radioing to a Frontier pilot lined up for the same runway.

From The Wall Street Journal • Mar. 24, 2026

I know there are several pastels on duty and they have regular rounds, checking each room.

From "Challenger Deep" by Neal Shusterman