on duty

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

The BBC has learned that Mudryk came into contact with the cardiovascular medication meldonium, which has the potential to increase respiratory capacity and stamina, while on duty with the Ukraine national team.

From BBC

Antoine Semenyo was unable to replicate his superb Premier League form while on duty with Ghana, failing to score in a 1-1 draw with Chad and 1-0 win over Mali, but still drew praise from coach Otto Addo for being a "lone fighter" in attack.

From BBC

"Perhaps the water marshals were not on duty when this boat took off," he said, adding that investigations had started.

From BBC

Padilla also spearheaded a letter last month to Acting Immigration and Customs Enforcement Director Todd Lyons seeking information about the agency’s policies regarding the identification of agents while on duty.

From Los Angeles Times

He added "Officers often find themselves dealing with unpredictable situations while on duty protecting the public, but it is unacceptable that they are put in harms way or injured by the irresponsible actions of others."

From BBC