The king of the Netherlands moonlights as a part-time commercial pilot, he told the Dutch newspaper De Telegraaf.

King Willem-Alexander has spent 21 years as a co-pilot for KLM Royal Dutch Airlines, working in the cockpit twice a month — even after he acceded to the throne in 2013.

It wasn't a secret that Willem-Alexander, who served in the Royal Netherlands Air Force, had a pilot's license. But no one knew how frequently he went incognito in the cockpit of regular commercial flights.

"I find flying simply fantastic," he told the newspaper, according to a BBC translation. "You can't take your problems with you off the ground. You can completely switch off for a while and focus on something else."

The king used to fly the Fokker 70, a narrow-body regional airliner. Now he's being retrained, so he can fly a Boeing 737. He said it "seemed nice to fly to other destinations one day, with more passengers and bigger distances," according to the BBC.

He told De Telegraaf that he's rarely recognized in his second job.

He said back before Sept. 11, when the cockpit door was open, he'd sometimes be spotted: "People regularly came to have a look and thought it was nice or surprising that I was sitting there," he said, according to a translation by The Guardian.

But walking through the airport in his uniform, he's rarely identified as the king. Same thing when he gives announcements during flights.

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