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

But the airline has attracted sharp criticism from the Airline Pilots Association of India, which said any relief granted to the airline on duty timings undermines the spirit of the new regulations and "gravely" compromises the safety of the flying public.

From BBC

It was from this place that Army National Guard Specialist Sarah Beckstrom, 20, who died Thursday, a day after being shot while on duty in Washington, D.C., embarked on a path of service that many had taken before her.

From The Wall Street Journal

“He took a life on duty—and realized another’s life after the fact—and to walk around with that is a difficult situation.”

From The Wall Street Journal

Meaning, essentially, that no one who was experienced and accomplished was on duty anywhere—on the news desks, at the jail.

From The Wall Street Journal

Parks officials were directed to keep employees who perform front-facing visitor services, such as maintenance and sanitation, on duty, along with essential law enforcement and emergency functions.

From Los Angeles Times