While announcements made by pilots over airplane speakers can tend to be muffled and difficult to understand, the next time you fly, listen closely to the voice over the intercom: There’s a chance you might be hearing the king of the Netherlands.

According to The New York Times, for the past 21 years, King Willem-Alexander of Holland has flown as a commercial co-pilot on the KLM Royal Dutch Airlines’ subsidiary Cityhopper airline twice a month. King Willem-Alexander ascended to the throne in the Netherlands in 2013, meaning that for four years, many a passenger has unknowingly been ferried to their destination by royalty.

The king made his revelation on Wednesday in an interview with the Dutch newspaper De Telegraaf. He said that having a hobby that requires all of his attention is a nice release.

“For me the most important thing is that I have a hobby for which I need to concentrate completely. You have an airplane, passengers and a crew,” The New York times quoted the king as telling De Telegraaf. “You carry responsibility for that. You cannot take your problems from the ground with you in the sky. You can for a brief moment disconnect and concentrate on something else. That is the biggest relaxation of flying to me.”

Willem-Alexander, 50, told the newspaper that prior to the Sept. 11, 2001, terrorist attacks, cockpit doors used to be left open quite often and that he was occasionally recognized by passengers peering up into the pilot’s area.

Given the expanded security measures of modern-day aviation, the king told De Telegraaf that now when he walks through Amsterdam Airport Schiphol in his pilot’s uniform, he often goes unnoticed by his subjects.

And when flying, Willem-Alexander says any time he addresses his passengers, he doesn’t state his name. He says that, save for a few exceptions, no passengers ever really recognize his voice.

“The advantage is that I can always say that I warmly welcome passengers on behalf of the captain and crew,” Willem-Alexander said in the interview. “Then I don’t have to give my name.”

Currently, KLM Cityhopper plans to retire its fleet of Fokker 70s — the aircraft the king is used to flying — in favor of Boeing 737s. Willem-Alexander told De Telegraaf that he plans to begin training on 737s so he can continue flying for KLM.

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