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]

---

Example Sentences

Tina, who is also in her 20s and comes from Rasht, told the BBC that she saw young people on duty in a square in the city on 14 March.

From BBC

Rocket launches can be impacted by different 'weather rules' which need to be met before the launch weather officer on duty can give the 'go' decision on weather.

From BBC

National Transportation Safety Board Chair Jennifer Homendy said the inquiry was ongoing and would include interviews with the two controllers on duty on Sunday night.

From BBC

When asked whether there was only one controller on duty at the time of the crash, Duffy said that was false.

From The Wall Street Journal

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